A lacustrine sediment record of the last three interglacial periods

from Clyde Foreland, Baffin Island, Nunavut:

biological indicators from the past 200,000 years

by

Cheryl Renee Wilson

A thesis submitted to the Department of Biology

in conformity with the requirements for

the degree of Master of Science

Queen’s University

Kingston, Ontario, Canada

(April, 2009)

Copyright © Cheryl Renee Wilson, 2009

ii

Abstract

The study of long-term climatic change in the Arctic, a region both particularly sensitive

to the effects of a warming climate and an important driver of global climate, is pertinent to

understanding the rates and magnitude of current ecosystem changes. Analyses on geological

time frames provide insight into the variability of Arctic climate, allowing a contextualized

understanding of recent ecosystem changes that have been documented across the Arctic. Lake

CF8, a mid-Arctic lake on Clyde Foreland, Baffin Island, contains a unique sedimentary archive

of the present and last two interglacial periods, due to past non-erosive glaciation patterns,

providing an opportunity to study interglacial climate trends. Diatom assemblages were analyzed

through the organic sediment record of the past three interglacials. Trends in the ontogeny of this

lake were revealed: the early, post-glacial environment was dominated by species of the colonial

Fragilaria genera, which transitioned into high relative abundances of tychoplanktonic

Aulacoseira species. Benthic/periphytic taxa, such as Psammothidium marginulatum, tended to

increase in relative abundance in the mid- to late-interglacial periods. The ecological

interpretation of this pattern is examined in this study, and suggests that climate drives the

succession of the diatom community primarily through indirect effects on lake ice and pH. The

extent of ice cover likely plays a large role in the biotic community of this lake; the diatom

assemblages within the past ~ 50 years indicate increasing littoral habitat complexity with a peak

in Eunotia species and a slightly acidic pH, which is discussed in relation to changing habitat

availability associated with decreasing ice cover. In-lake production was examined through the

use of spectrally-inferred chlorophyll a trends, which also indicate elevated production in the past

~ 50 years. As climate change becomes an increasingly significant threat to the stability of Arctic

ecosystems, interest in paleoclimate records that extend into past, non-anthropogenically mediated

warm periods, is increasing. This sediment record extends our understanding of past

iii

environmental trends beyond the longest records in this part of the Arctic, the Greenland ice core

records, and enhances our understanding of the variability of Arctic climate.

iv

Acknowledgements

My fascination in the field of paleolimnology stems from an undergraduate course taught

at Queen’s University by John P. Smol. Ultimately, completing work in his lab as an

undergraduate student and progressing into a Masters has revealed my immense passion for

environmental study and protection. I sincerely thank John for introducing me to long-term

paleoclimatic research, and for his superb teaching and supervision.

My present Masters work was introduced to me by Alexander P. Wolfe of the University

of Alberta, whose excitement for the potential scientific discoveries that lay within this unique

sediment record is truly infectious.

The members of P.E.A.R.L. are a remarkable group of dedicated and helpful researchers

and students, and my involvement in this lab has been an exceptionally positive academic

experience. I would like to specifically thank Kathleen Rühland for her constant guidance, from

diatom taxonomy to understanding the ‘big picture’ of my work, as well as Neal Michelutti for

providing an expert perspective in all aspects of the Lake CF8 research. My additional Masters

committee members, Scott Lamoureux and Brian F. Cumming, have provided valuable guidance

throughout the project.

My Masters work has also introduced those close to me to the wonderful world of

paleolimnology; to my family and friends, for always excitedly listening to my ideas (and

proofreading!), thank you.

v

Table of Contents

Abstract ii

Acknowledgements iv

Table of Contents v

List of Figures vii

List of Tables viii

List of Abbreviations ix

Chapter 1, Introduction and Literature Review 1

1.1 The Importance of Arctic Paleoenvironmental Records 1

1.2 Past Environments and Climate of Baffin Island, Nunavut 2

1.2.1 Holocene Epoch 3

1.2.2 Last and Previous Interglacials 5

1.3 Lake CF8 on Eastern Baffin Island 7

1.4 The Lake CF8 Paleolimnological Thesis Project 10

Chapter 2, Site Description and Methods 13

2.1 Site Description 13

2.2 Field and Laboratory Methods 14

2.3 Statistical Analyses 16

2.4 Acknowledgements 17

2.5 Tables and Figures 18

2.5.1 Captions 18

Chapter 3, Results 22

3.1 Core Characteristics and Chronologies 22

3.2 Diatoms 24

3.2.1 Zone 1 25

3.2.2 Zones 2 and 3 26

3.2.3 Zone 4 27

3.2.4 Zones 5 and 6 28

3.2.5 Zone 7 29

vi

3.3 Spectrally-Inferred Chlorophyll a 30

3.4 Figures 31

3.4.1 Captions 31

Chapter 4, Discussion 35

4.1 Patterns of Diatom-Inferred Lake Development Throughout 36

Each Interglacial Period

4.1.1 The Holocene Interglacial 37

4.1.2 The Interstadial Sediments 43

4.1.3 The Last Interglacial 44

4.1.4 MIS 7 49

4.1.5 Trends Between the Three Interglacial Diatom Records 50

4.2 Climate, DIpH and Diatom Succession 52

4.3 The Recent Lake CF8 Sediments 56

4.4 Summary and General Conclusions 60

4.5 Figures 62

4.5.1 Captions 62

References 63

Appendices 74

A. Diatom synonyms and authorities for dominant species 74

B. Raw diatom counts, surface core 75

C. Raw diatom counts, Holocene core 81

D. Raw diatom counts, interstadial core 93

E. Raw diatom counts, LIG core 94

F. Raw diatom counts, MIS 7 core 109

G. 210Pb age model, surface core (published data, Thomas et al. 2008) 114

H. 14C age model, Holocene core (published data, Axford et al. 2008) 117

I. 14C ages, interstadial core (published data, Briner et al. 2007a) 119

J. OSL ages, LIG and MIS 7 core (published data, Briner et al. 2007a) 120

.

vii

List of Figures

Chapter 2, Site Description and Methods

Figure 1a. The approximate location of Clyde Foreland on the eastern 20

coast of Baffin Island, Nunavut, Canada

Figure 1b. A local topographical map of Clyde Foreland, specifically showing 21

the location of Lake CF8

Chapter 3, Results

Figure 2. Density (g/cm3) throughout the Lake CF8 sediment record 32

Figure 3. Diatom stratigraphy for the Lake CF8 sediment record. 33

Figure 4. Spectrally-inferred chlorophyll a through the CF8 sediment record 34

Chapter 4, Discussion

Figure 5. A local topographical map of Clyde Foreland, showing the location 62

of Lakes CF10 and CF11 in relation to Lake CF8

viii

List of Tables

Chapter 2, Site Description and Methods

Table 1. Surface water chemistry measurements 18

Table 2. All available dates from the multiple Lake CF8 cores, 19

indicating dating type and source

ix

List of Abbreviations

DCA detrended correspondence analysis DIpH diatom-inferred pH ka thousand years ka BP thousand years before present LIG Last Interglacial, sensu lato in this study LIS Laurentide Ice Sheet MIS 7 Marine Isotope Stage 7

1

Chapter 1 Introduction and Literature Review

1.1 The Importance of Arctic Paleoenvironmental Records

Although it is now widely recognized that greenhouse gas emissions have affected global

climate, the rate, magnitude, and timing of natural and anthropogenic influences are still poorly

understood for many regions and time scales. High latitude regions are particularly sensitive to

the effects of warming, attributable to an array of cryosphere-driven positive feedbacks (e.g.

Holland and Bitz 2003; IPCC 2007; Moritz et al. 2002; Overpeck et al. 1997; Serreze et al. 2007).

Polar regions also play a disproportionately large modulating role in the global climate system

(e.g. ACIA 2005). These regions are thus particularly vital to monitor and study for a better

understanding of both the effects and rates of current climate change. Although long-term

monitoring data are often absent or spatially inconsistent in the north, indirect proxy methods can

be used to study past environmental and climatic trends. Evidence of modern warming in the

Arctic, including paleoecological studies spanning beyond ‘modern’, is definitive and mounting

(e.g. Chapman and Walsh 1993; Hughen et al. 2000; Jones et al. 2001; Michelutti et al. 2003;

Smol et al. 2005; Smol and Douglas 2007a, b). For example, Smol and Douglas (2007a) showed

that a significant ecological threshold, the desiccation of tundra ponds for the first time in

millennia, has recently been crossed in some ponds on Ellesmere Island.

Paleoenvironmental records are also increasingly valuable on longer time frames,

particularly to illustrate the range of natural variability and rates of change in Arctic lakes and

ecosystems. The climatic and environmental shifts of the Holocene epoch, the current

interglacial period that began after the last deglaciation, have been characterized using

paleoenvironmental evidence across the Arctic (e.g. Barber et al. 1999; Briner et al. 2006; CAPE

Project Members 2001; Finkelstein and Gajewski 2007; Kaufman et al. 2004; Kerwin et al. 2004;

LeBlanc et al. 2004; Michelutti et al. 2007; Overpeck et al. 1997; Smol et al. 2005; Thomas et al.

2

2008). However, the understanding of long-term natural climatic variability on longer, geological

time frames is less well defined (e.g. Desprat et al. 2006; Wolfe and Smith 2004). The

interglacials of the Quaternary (the period spanning the past 1.8 million years that encompasses

the Pleistocene and Holocene epochs) are regarded as archetypal periods that provide

comparative references to understand the characteristics of a full interglacial cycle unaffected by

anthropogenic influences (e.g. van Kolfschoten et al. 2003; Wolfe and Smith 2004). While

paleoenvironmental records spanning interglacial periods are infrequent, they are important to

forming a contextualized understanding of future environmental and climatic changes in the

Arctic.

1.2 Past Environments and Climate of Baffin Island, Nunavut

The paleoclimatic record of the Baffin Bay region may be an important indicator of past

climate across the Arctic region as a whole (Bradley and Miller 1972; Williams and Bradley

1985). As described by Williams and Bradley (1985), Keen (1980) determined that summer

temperatures on Baffin Island are highly correlated with the temperature fluctuations of a large

portion of the Arctic due to its position with respect to the mid-tropospheric trough over North

America, although Serreze et al. (2000) have shown that the current temperature changes on

Baffin Island are less in comparison to other areas of the Arctic, such as the high Canadian Arctic

islands. Furthermore, due to the continued presence of remnants of continental ice, and the

modern and past fluctuations of that ice, Baffin Island represents a region suitable for the

monitoring and long-term study of climatic change (e.g. Andrews et al. 1972; Bradley and Miller

1972). Environmental, ecological and climatic descriptions of Baffin Island throughout the

Holocene (past 10 thousand years before present, or ka BP) and farther into the Pleistocene epoch

(approximately 1.8 million years ago until 10 ka BP) extend from geological and glaciological

3

reconstructions, in addition to palynological and other paleolimnological proxy studies (Williams

and Bradley 1985).

1.2.1 Holocene Epoch

The dominant feature that affected paleoclimates and paleoecology of the Baffin Bay

region was the presence of the Laurentide Ice Sheet (LIS) that glaciated most of Canada and the

northern United States. The Foxe Dome of the LIS covered much of Baffin Island throughout the

Quaternary Period, and was more expansive than previously thought (e.g. Briner et al. 2003;

Marsella et al. 2000), continuing through the Pleistocene epoch before retreat at the end of the last

glacial cycle (e.g. Miller et al. 2005; Wolfe and Smith 2004). The LIS extended to the

continental shelf off the east coast of Baffin Island during the last glacial maximum (e.g. Marsella

et al. 2000); rapid retreat of the continental LIS had begun by 15 ka BP to 11 ka BP (Miller et al.

2005), although extensive spatial heterogeneity of glacial advances and eventual retreat was

common (e.g. Marsella et al. 2000). Northeastern coastal lowlands were likely ice free by

approximately 14 ka BP, identified through cosmogenic exposure dating of glacially deposited

erratics (Miller et al. 2005). The LIS retreated from coastal fiords prior to interior regions;

deglaciation was sequential in Clyde Inlet (northeast Baffin Island), with ice-free lowlands at 12.5

ka BP, outer fiord deglaciation at 10.3 ka BP and inner fiord ice retreat by 9.4 ka BP (Briner et al.

2007b). The interior of Baffin Island, as well as some fiord regions, may have remained ice-

covered until 8 ka BP to 7 ka BP (Anderson et al. 2008; Miller 1973), likely due to a glacial

advance, termed the Cockburn Substage, that occurred on the east coast of Baffin Island at

approximately 9.5 ka BP, with another advance at 8.2 ka BP (e.g. Miller et al. 2005; Wolfe and

Smith 2004). The Penny and Barnes ice caps are the vestigial remnants of the LIS (Dyke and

Prest 1987).

Initial post-glacial temperatures on eastern Baffin Island were cooler than present,

although inferred lacustrine productivity peaked in the early Holocene and modern vegetation

4

was broadly established by approximately 8 ka BP (Kerwin et al. 2004; Miller et al. 2005). A

regionally well-defined warm period from 10 ka BP to 8.5 ka BP has been indicated for the Clyde

Foreland on northeastern Baffin Island as 5°C warmer than modern summer temperatures (Briner

et al. 2006). The Greenland NorthGRIP isotope record indicates regional climate variability for

the first 1.5 ka (thousands of years) of the Holocene epoch, with a distinct cold event at 8.2 ka BP

(Johnsen et al. 2001). Similarly, abrupt cold reversals during the early-Holocene warming trend

have been indicated by chironomid (insects of the family Chironomidae) remains in lacustrine

sediments from the Clyde Foreland (Axford et al. 2008), as well as by proxies for lake production

including LOI (loss-on-ignition, an indicator of organic carbon content; Heiri et al. 2001) and

total organic %N (Briner et al. 2006). A warm period from 6 ka BP to 3 ka BP has been

identified through pollen studies across North America (Viau et al. 2006). Similarly, pollen

reconstructions across Baffin Island reflect mid-Holocene temperatures at least 1°C to 2°C

warmer than present summer temperatures; in particular, Clyde River was 1°C warmer than

present by 6 ka BP (Kerwin et al. 2004). A regional climatic optimum has also been defined in

the early- to mid-Holocene (e.g. Levac et al. 2001) from 6.8 ka BP to 5.7 ka BP, which likely

extended until approximately 3 ka BP across Baffin Island (Williams and Bradley 1985),

although a palynological perspective indicates cooling from 5.7 ka BP to 4.5 ka BP (Short et al.

1985). Neoglaciation followed, and likely began by approximately 7 ka BP to 6 ka BP in the

mid-Holocene (e.g. Briner et al. 2006), with intensified cooling after 3.6 ka BP to 2.5 ka BP

(Kerwin et al. 2004; Levac et al. 2001; Miller 1973; Miller et al. 2005; Wolfe 2003), although

Miller (1973) suggested that the oldest Neoglacial moraines date at 3.2 ka BP. Neoglaciation led

into the Little Ice Age of approximately 1450 to 1850 AD, which is characterized regionally (e.g.

Johnsen et al. 2001; Podritske and Gajewski 2007) and across Baffin Island (e.g. Moore et al.

2001), with minimum temperatures at approximately 350 yr BP (Williams and Bradley 1985).

Following the lower temperatures of the Little Ice Age, modern warming of approximately the

5

past 150 years, or the Anthropocene, has been documented across Baffin Island (e.g. Hughen et

al. 2000; Michelutti et al. 2007; Thomas et al. 2008).

Holocene climatic shifts on Baffin Island were dominantly controlled by altered

atmospheric and oceanic dynamics influenced by the deteriorating LIS, as well as declining

summer insolation through the Holocene (e.g. Berger and Loutre 1991; Briner et al. 2006; Miller

et al. 2005; Overpeck et al. 1997), resulting in increased seasonality and spatial heterogeneity of

temperatures in the early Holocene (Berger and Loutre 1991; Williams and Bradley 1985).

Marine sediment cores have also indicated temperature variability throughout the Holocene. For

example, Levac et al. (2001) used dinoflagellate cyst assemblages to indicate that sea surface

temperatures declined towards modern values through the Holocene but may have periodically

fluctuated by over 4°C. Temperature fluctuations, therefore, were common throughout the

Holocene epoch, which is characteristic of an interglacial period. Though an interglacial period

typically ends in a climatic deterioration into a new glacial period, mediated primarily by

insolation patterns, modern warming has been suggested to be stalling the progression into a

glacial mode because radiative forcing associated with anthropogenic greenhouse gas emissions

exceeds that associated with orbital geometry. Consequently, Berger and Loutre (2002) have

predicted that the Holocene interglacial may become protracted in the order of 50 ka beyond the

present.

1.2.2 Last and Previous Interglacials

Terrestrial and marine paleoclimate studies have indicated that the climate of Baffin

Island, as well as the eastern Canadian coast and adjacent Baffin Bay, was warmer throughout

several periods of the Pleistocene relative to both early Holocene and present (late Holocene)

conditions (Andrews et al. 1988; de Vernal et al. 1991; Johnsen et al. 1997; Kukla et al. 2002;

Miller et al. 1977). Larger variability, or oscillations, in insolation occurred throughout Marine

Isotope Stage 5 (MIS 5), or the Last Interglacial (LIG) sensu lato, approximately 75 to 130 ka BP,

6

compared to the Holocene interglacial (Loutre and Berger 2003). Marine Isotope Stage 7 (MIS

7), an interglacial sometimes referred to as the Previous Interglacial, centered at approximately

225 ka BP, also experienced significant variations in insolation (Desprat et al. 2006).

Forelands comprised of thick sequences of Quaternary glacial, marine, and terrestrial

deposits characterize portions of the outer east coast of Baffin Island between Clyde Inlet and

Eglinton Fiord. These forelands record past high sea levels associated with glacially induced

isostatic depression and postglacial marine transgressions, leaving multiple marine sequences

containing dateable fossils that have furthered the understanding of the last glacial-interglacial

cycle in this region (e.g. Andrews et al. 1988; Miller et al. 1977). Marine mollusc remains and

pollen assemblages in overlying soils from the cliffs of the Clyde Foreland on eastern Baffin

Island indicate higher than present summer temperatures at approximately 130 ka BP, or the LIG

sensu stricto period, MIS 5e (deVernal et al. 1991; Miller et al. 1977; Mode 1985; van

Kolfschoten et al. 2003). At this time, the Greenland Ice Sheet extensively melted (Koerner

1989), and abrupt climatic instabilities have been inferred (Johnsen et al. 1997; Wolfe et al.

2000). Further, the warm summer seasons of the LIG, in addition to the span of the interglacial,

were likely longer than that of the Holocene (Fréchette et al. 2006, 2008; Miller et al. 1977).

Pre-Holocene lacustrine sediments beyond the limit of radiocarbon dating have also been

discovered beneath glacial till at several locations across Baffin Island (Briner et al. 2007a;

Fréchette et al. 2006; Miller et al. 1999; Steig et al. 1998; Wolfe and Härtling 1996; Wolfe et al.

2000). Miller and colleagues (1999) identified sediments likely deposited at approximately 85 ka

BP, constrained using several types of luminescence dating, that indicate periods when LIG

summer temperatures were warmer than those of the Holocene. In addition, the low-Arctic

vegetation zone shifted farther north during the LIG than at any time during the Holocene

(Fréchette et al. 2006; Miller et al. 1999). Pollen concentrations in LIG sediments were

significantly higher than during the Holocene (e.g. Fréchette et al. 2006; Wolfe et al. 2000);

vegetation patterns and pollen concentrations led Fréchette and colleagues (2006) to infer LIG

7

July air temperatures to have been a minimum of 4°C to 5°C higher than present on eastern

Baffin Island, in agreement with chironomid-inferred summer temperatures (8°C higher than

present, Francis et al. 2006; Axford 2007) and δ18O inferred paleotemperatures from Greenland

ice cores (Johnsen et al. 2001). Late LIG climatic conditions deteriorated, indicated by declines

in low-Arctic vegetation pollen (Miller et al. 1999) and a lack of lacustrine sedimentation

between the LIG and the Holocene (Francis et al. 2006). However, periods of glacial advance

and retreat occurred throughout the Late Wisconsinan (the most recent glaciation cycle). For

example, Steig and colleagues (1998) identified an organic layer of lake sediments from Fog

Lake between inorganic layers, implying prolonged periods of enhanced limnological activity

prior to 35 ka BP but not within the LIG.

While insolation is the primary driver of glacial-interglacial cycles, ice-sheet presence

and attendant effects on atmospheric circulation patterns likely further influenced regional

climate (e.g. Melles et al. 2007). The Holocene, LIG and MIS 7 interglacial periods in the Baffin

Island area of the Arctic differed in the range of variability of insolation patterns, as well as the

prevalence and effects of continental glaciation, and the time span of each period; however, each

represents a period of warmth unaffected by anthropogenic influences, and thus have increasingly

become research targets with which to compare our modern warm climate.

1.3 Lake CF8 on Eastern Baffin Island

Due to the glacial history of northern Canada, lacustrine sediment records typically

extend only to the end of the last glaciation, and thus longer sequences, which would capture

warmer interglacial periods and possible analogues for future climate changes, are generally

unavailable. However, the Clyde Foreland region of eastern Baffin Island contains lakes with

well-preserved sedimentary records from the last several interglacial periods (Briner et al. 2007a).

The preservation of interglacial sediment sequences within lake basins indicates that successive

8

glaciations, which decreased in magnitude through the last glacial cycle on eastern Baffin Island

(Steig et al. 1998), have not removed evidence of past interglacials (e.g. Briner et al. 2005).

Portions of Baffin Island and the Ungava Peninsula, particularly uplands, exhibit little evidence

of glacial erosion (e.g. Andrews et al. 1985). Cold-based, non-scouring glaciation is likely

responsible for this paucity of erosional evidence (Davis et al. 2006; Miller et al. 2002), which

was previously interpreted as indicative of unglaciated refugia (e.g. Steig et al. 1998). Briner and

colleagues (2003, 2005) confirmed, through cosmogenic exposure dating of erratics, that the LIS

was cold based during several advances, including the last glacial maximum, on portions of the

eastern coast of Baffin Island creating a heterogeneous landscape in relation to glacial scour.

Briner and colleagues (2007a) successfully cored Lake CF8 (see Methods for full site

details) on eastern Baffin Island and recovered multiple organic gyttja units of sedimentation

between alternating sand layers, which temporally captures approximately the past 200 ka. In

addition to a surface core that provides a high-resolution record of recent sedimentation, the

upper gyttja unit collected from Lake CF8 represents the Holocene epoch, the interglacial period

that began approximately 12 ka BP following the retreat of the LIS at this site (Briner et al.

2007a). A thin organic unit below the Holocene gyttja has been assigned to an interstadial within

the LIG, following the peak warmth of full interglacial conditions (Briner et al. 2007a). The term

Last Interglacial (LIG) sensu lato commonly refers to the whole of MIS 5 (e.g. Kukla et al. 2002),

although the only period considered to be as warm as the present or Holocene during the LIG is

MIS 5e, the earliest of the five divisions of MIS 5 (Emiliani 1955, 1966; Shackleton 1969;

Koerner 1989). Kukla et al. (2002) described the temporal limits of MIS 5e as rather arbitrary,

set at 116 ka BP to 130 ka BP. The sediments recovered from the basin of Lake CF8 contain a

gyttja unit dated to within early MIS 5; Briner et al. (2007a) have tentatively assigned an age of

MIS 5e, though this discussion will refer to this period as the LIG, which, sensu lato,

encompasses all of MIS 5 but refers to full interglacial conditions. The deepest gyttja unit

9

recovered from Lake CF8 corresponds to a warm interval within MIS 7, which is also subdivided

into five stages of oscillating warm and cold conditions (Desprat et al. 2006; Emiliani 1955,

1966). This unit will be referred to as MIS 7, as a more refined age has not been determined

(Briner et al. 2007a).

Paleoenvironmental records that extend through glacial cycles are present, though sparse,

across the Arctic. Relict landscapes from beneath continental glaciers have been identified from

within the limits of the LIS (e.g. Briner et al. 2005), the Fennoscandian ice sheet (e.g. Stroeven et

al. 2002), as well as the Antarctic ice sheet (Lewis et al. 2008). The longest ice-core records from

the northern hemisphere extend partway through the LIG (Dahl-Jensen 1998). Lacustrine records

from eastern Baffin Island have recorded the LIG, including multiple mid-Arctic lakes on

Cumberland Peninsula (Francis et al. 2006; Fréchette et al. 2006; Wolfe and Steig 1996; Wolfe et

al. 2000) and on Brevoort Island (Miller et al. 1999). Terrestrial evidence from marine incursions

also dates beyond the Holocene on Baffin Island (Miller 1985; Mode 1985; Steig et al. 1998).

Several additional lacustrine records extending into past interglacials have been located on

northern Ungava Peninsula in Canada (Pingualuit Crater; e.g. Grönlund et al. 1990) and

northeast Russia (El’gygytgyn Crater Lake, e.g. Melles et al. 2007; Lake Baikal, e.g. Rioual

and Mackay 2005). Melles and colleagues (2007) have reconstructed multiple warm periods

extending to within MIS 8, over 250 ka BP, alternating with cold and dry periods, as well as

cold and moist climates, likely dominantly controlled by insolation and atmospheric

circulation patterns. The Lake CF8 sediment sequences represent one of a few organic records

containing multiple interglacial periods recovered from within the limits of continental glaciation,

and provide a unique opportunity to reconstruct lacustrine environmental conditions throughout

several past warm periods using multiple proxy indicators.

10

1.4 The Lake CF8 Paleolimnological Thesis Project

Paleolimnology, the study of lake histories using information preserved in sediment

profiles, represents a powerful tool for reconstructing past climates in the Arctic (Pienitz et al.

2004). The Lake CF8 sediment record has been examined by several researchers (Axford 2007;

Axford et al. 2008; Briner et al. 2007a; Thomas et al. 2008) using multiple proxy indicators of

past climate. A detailed lithological profile, as well as a theoretical model of the deposition of

each sediment unit, is available in Briner et al. (2007a). Thomas et al. (2007) examined the

chironomid record of the late Holocene, and Axford et al. (2008) extended that research to

include the entire Holocene sequence. Further, chironomids have been examined through the full

length of the record (Axford 2007), in addition to other biological proxies such as LOI, biogenic

silica (% BiSi), and the carbon to nitrogen ratio (which, in this system, was interpreted to indicate

the relative abundance and productivity of aquatic phytoplankton and macrophytes). Magnetic

susceptibility, a measure of terrestrial sediment influx, was also measured along the length of the

CF8 sediment record (Briner et al. 2007a).

The preserved biological fossil record also includes aquatic algae of the class

Bacillariophyceae, or the diatoms, which are frequently used as proxy indicators in

paleoecological studies due to excellent preservation in sedimentary profiles, as well as the

abundance and identifiable nature of siliceous valves, the ultrastructure of individual cells

(Douglas and Smol 1999; Smol and Cumming 2000). The specialized ecological and

limnological characteristics that shape diatom community assemblages (Birks 1998) have been

examined for a range of environments on Baffin Island (Joynt and Wolfe 2001); diatoms were

chosen as the primary proxy indicator for the present study, examined at high resolution

throughout the CF8 sediment record. Additionally, spectrally-inferred chlorophyll a

concentrations were measured to infer overall productivity.

11

An array of related studies at the Holocene and LIG scales have been conducted in the

region surrounding Lake CF8, providing the framework for the current investigation. The

sediment record from Lake CF3, a similar sized lake that lies closer to the coast of Baffin Bay

than Lake CF8, indicated that this lake responded primarily to radiative forcing in the early

Holocene, with a diminished effect of the waning LIS (Briner et al. 2006). The CF3 record was

examined using diatom-inferred pH (DIpH) and chironomid-inferred temperatures to establish

that a pronounced early Holocene thermal maximum occurred at 10 ka BP to 8.5 ka BP, with

progressive cooling thereafter (Briner et al. 2006). Further, a record from Fog Lake on

Cumberland Peninsula, to the southeast of Lake CF8, contains both Holocene and LIG

sedimentation (Wolfe et al. 2000). These researchers determined that the diatom assemblages

responded to climatic variability during the LIG, and made explicit comparisons between the

Holocene and LIG records. Miller et al. (1999) also examined sediments of both Holocene and

interglacial age in Robinson Lake and made comparisons between each period in terms of diatom

and pollen floras, as well as catchment processes. The Lake CF8 record will be compared to the

CF3 Holocene record and the Fog Lake and Robinson Lake Holocene and LIG records. A

primary interest in this thesis is forming an understanding of interglacial Arctic lake ontogeny,

and thus comparisons will be made between the interglacials preserved in the Lake CF8 record as

well as with other interglacial records on Baffin Island and elsewhere in the Arctic. In addition,

this sediment record has preserved climatic change over multiple interglacial periods unaffected

by anthropogenic factors, and an attempt will be made to compare recent limnological change

with that of past warm periods.

Finally, this investigation examines the longest temporal lacustrine sediment record

recovered from the Canadian Arctic and within the limits of the LIS. Further, this sediment

record has been reliably dated throughout three interglacial periods (Briner et al. 2007a; Axford et

al. 2008); other pre-Holocene records in the Canadian Arctic have presented challenging dating

12

results (e.g. Miller et al. 1977; Wolfe and Härtling 1996; Wolfe et al. 2000). This multiproxy

record extends our understanding of past interglacial cycles and the corresponding ecological

ranges associated with warm periods unaffected by anthropogenic forcings, and will allow the

first explicit comparison of recent climatic changes to multiple past interglacials within the

bounds of the former LIS.

13

Chapter 2

Site Description and Methods

2.1 Site Description

Lake CF8 (informal name; 70°33’ N, 68°57’ W) is situated 195 m above sea level

approximately 13 km west of Baffin Bay and 17 km northwest of the hamlet of Clyde River on

the Clyde Foreland of eastern Baffin Island, Nunavut, Canada. Figure 1a shows the approximate

position of the Clyde Foreland on eastern Baffin Island, and Figure 1b shows an elevation

perspective of the foreland and the specific location of Lake CF8. The foreland, a coastal

lowland, stretches approximately 50 km from the Kogalu River in the north to the Clyde River

and Patricia Bay in the south, and 20 km eastward from a line of inland mountains to the cliffs of

the coast of Baffin Bay. The bedrock in the Clyde Foreland region is composed of Precambrian

granite and gneiss; a detailed geological profile of the region is described by Briner et al. (2005).

The LIS covered the Clyde Foreland surrounding Lake CF8 throughout the Quaternary glacial

cycles, with the most recent deglaciation, dated by cosmogenic exposure dating of erratics, at

approximately 12 ka BP (Briner et al. 2005).

Lake CF8 has a surface area of 0.3 km2 and maximum depth of 10 m, with at present no

significant inflow but evidence of an abandoned lateral meltwater channel in the small,

undisturbed catchment (1.1 km2) (Briner et al. 2007a). The thirty-year mean annual temperature

at Clyde River is -12.8°C, with average positive temperatures from July through September and

233 mm/yr of primarily snow-based precipitation (Environment Canada 2008; Thomas et al.

2008). The lake is currently dilute and largely unbuffered, oligotrophic, and slightly acidic,

similar to numerous other lakes on the Clyde Foreland (e.g. Michelutti et al. 2005) and other

areas of Baffin Island with similar geology (e.g. Miller et al. 1999; Wolfe et al. 2000). Water

14

chemistry measurements are shown in Table 1. The modern vegetation of this region is classified

as the prostrate shrub zone (Edlund and Garneau 2000), with abundant heath taxa and bryophytes.

2.2 Field and Laboratory Methods

The sediment cores used for diatom analysis were collected over several field seasons

from 2002 to 2006 using a sled-mounted percussion coring system (Nesje 1992) as well as a

surface gravity corer described in detail elsewhere (e.g. Axford et al. 2008; Briner et al. 2007a).

The multiple cores represent sedimentation that temporally spans from the present (2005 AD) to

the previous interglacial, or MIS 7, encompassing approximately the past 200 ka, though the

complete MIS 7 sediment record has not yet been attained.

Unprocessed lacustrine sediments require chemical digestion to remove organic matter

prior to diatom analysis (Battarbee et al. 2001). The surface, Holocene and LIG sediments were

processed entirely at the University of Alberta. Approximately 0.10 g of freeze-dried sediment

from each subsection was digested with room-temperature 10% H2O2 and hot 30% H2O2, rinsed

with distilled water until neutral pH was achieved, and spiked with a known quantity of

Eucalyptus pollen (Wolfe 1997) prior to mounting onto glass slides with Naphrax® (a high

refractive index mounting medium). The interstadial sediments were digested using a microwave

technique (Parr et al. 2004) at Queen’s University due to the high organic content; approximately

0.10 g of freeze-dried sediment was placed into Teflon vials with 10 mL H2NO2, digested at a

high temperature and pressure, and rinsed with distilled water and mounted with Naphrax® onto

glass slides. The MIS 7 sediments were also digested at Queen’s University using a 50:50 molar

ratio of HNO3 to H2SO4 (Battarbee et al. 2001) and washed with distilled water until neutral pH

was attained prior to mounting onto glass slides with Naphrax®.

15

Initially, a minimum of 200 diatom valves was discussed as sufficient to provide an

accurate representation of the diatom community assemblage from each interval. However, a

minimum of 400 valves was easily obtainable, and thus a minimum of 200-400 diatom valves

were enumerated for each interval in multiple transects that covered a representative area of each

coverslip, using a Leica DMR microscope at 1000x magnification with differential interference

contrast (DIC) and an oil-immersion objective and condensor lens. Diatom identification was

carried out to the lowest possible taxonomic level (species or variety). The diatom taxonomy was

correlated with Joynt and Wolfe (2001), and followed numerous sources including Antoniades et

al. (2008), Camburn and Charles (2000), Fallu et al. (2000), Krammer (1992, 2000), Krammer

and Lange-Bertalot (1986, 1988, 1991a, 1991b), and Lange-Bertalot (2001). Appendix A

contains a list of all dominant diatom species with taxonomic authorities and synonyms; the

names of several genera have followed the recommendations of Round et al. (1990). Raw diatom

counts were converted to percent relative abundance and presented in a stratigraphical profile

generated using the computer program C2 Data Analysis V.1.4.3 (Juggins 1991). The attempt at

determining quantitative estimates of diatom concentrations using spikes of known quantities of a

foreign pollen grain was unsuccessful, due to clumping of the pollen as well as drift from the

ideal 1:1 ratio of diatom valves to pollen grains required for quantitative estimates of diatom

concentrations. Scanning electron microscopy images were obtained for the MIS 7 sediments to

confirm the taxonomic identities of the Aulacoseira taxa in this interglacial.

Chlorophyll a concentrations, a proxy of overall primary production (Michelutti et al.

2005; Wolfe et al. 2006), were determined using spectral reflectance throughout the length of the

CF8 sediment record. This technique uses visible near-infrared reflectance spectroscopy to

measure the concentrations of chlorophyll a, its derivative isomers and all degradation

pheopigments (Wolfe et al. 2006b; Michelutti et al. 2009). Freeze-dried, sieved (<125 µm)

sediments were analysed using a FieldSpecPro, as well as a Foss NIRSystems Rapid-Content

16

Analyzer 6500, for spectra between 350 nm and 2500 nm. The trough between 650 nm to 700

nm was used in the model developed by Michelutti et al. (2005) to indicate overall chlorophyll a

concentrations. Michelutti et al. (2005; 2009) have previously demonstrated the effectiveness of

this technique in the Clyde River region and elsewhere.

The geochronology of the CF8 sediment record has been examined by several

investigators (Axford et al. 2008; Briner et al. 2007a; Thomas et al. 2008), and is based on

multiple dating methods including 210Pb, radiocarbon and optically-stimulated luminescence

dating. Table 2 lists all dates available from multiple cores. The present study utilized two

undated cores representing an interstadial and LIG sedimentation; while the dates in Table 2 are

therefore not directly comparable by core depth for these two units, the gyttja units from each

core coincide and thus general dates may be inferred.

2.3 Statistical Analyses

A pH transfer function developed by Joynt and Wolfe (2001) from 61 Baffin Island lakes

similarly situated primarily on crystalline terrain was used to reconstruct pH trends in the CF8

sediment record. Lake CF8 lies approximately in the middle of the latitudinal transect used for

the training set sites, indicating that analogues to past limnological conditions are likely to be

present in the training set. The pH transfer function was applied using C2 V 1.4.3 (Juggins

1991), with a weighted-averaging model with classical deshrinking and bootstrapping. The

down-core DIpH was subsequently used in a detrended correspondence analysis (DCA), using

CANOCO V 4.5 (ter Braak and Šmilauer 2002), to assess if DIpH tracked the main direction of

variation in the diatom community structure. DCA is a unimodal ordination method that provides

an indication of turnover rate measured as standard deviation units along a gradient that explains

major variations in the data. The relative abundance diatom data was square-root transformed for

17

this analysis, with no down-weighting of rare taxa. The DCA axis 1 sample scores were

regressed against DIpH, with r (correlation coefficient) values of 0.73, 0.96, 0.35, 0.81 and 0.35

for the surface, Holocene, interstadial, LIG and MIS 7 cores, respectively. The DCA axis 1

sample scores (axis 1 represents the majority of the data variation) and DIpH were plotted against

depth on the diatom stratigraphy to summarize changes in the diatom assemblage data. Hill’s N2

(Hill 1973), a quantitative indicator of species diversity, or the effective number of taxa in each

interval, was also attained using C2.

2.4 Acknowledgements

Multiple researchers were involved in the technical aspects of this study, related to this

and other research at Lake CF8. The preparation of the diatom samples performed at the

University of Alberta was conducted by Kristopher Hadley and Set Castro, working in the

laboratory of Alexander P. Wolfe. The preparation of samples for chlorophyll a analysis was

conducted by the author at Queen’s University, as well as Neal Michelutti and Colin Cooke,

based at the University of Alberta at the time of analysis. Neal Michelutti completed 210Pb and

14C dating of the surface core, and the development of an age model was conducted by Thomas et

al. (2008), while the dating of the other cores (14C and OSL) was conducted by Briner et al.

(2007a) and Axford et al. (2008). Scanning electron microscopy images were obtained by

Alexander P. Wolfe. The author performed all diatom counting and subsequent analysis.

18

2.5 Tables and Figures

2.5.1 Captions

Table 1. Surface water chemistry measurements collected from Lake CF8 in May 2006 under full ice cover. (N. Michelutti unpublished data). Table 2. All dates from the CF8 sediment record including the source. Dates include 210Pb dates, AMS radiocarbon (14C) dates, and optically stimulated luminescence (OSL) dates. See Appendices G through J or source publications for age models and details. Two dated cores (*) were not used for diatom analysis due to unavailability of sediment, though the positions of the gyttja units are comparable across all cores and thus these dates were used to estimate the approximate ages of the gyttja units studied. Figure 1a. A map of the eastern Canadian Arctic region. The approximate study location is indicated. From: The Atlas of Canada, Natural Resources Canada (2009). Figure 1b. A map of Clyde Foreland, Baffin Island, Nunavut, Canada, showing elevation and the location of Lake CF8 (70°33’ N, 68°57’ W). From: A.P. Wolfe.

Table 1.

TN (µg/L) 327 TDN (µg/L) 316 TP (µg/L) 3.90 TDP (µg/L) 1.40 DOC (mg/L) 0.97 DIC (mg/L) 0.74 Cl (mg/L) 3.74 SO4

2- (mg/L) 0.80 Na (mg/L) 2.13 K (mg/L) 0.29 Ca (mg/L) 0.36 Mg (mg/L) 0.30 Al (mg/L) 0.01 Si (mg/L) 1.07 Conductivity (µS/cm) 18.84 pH 6.26

19

Table 2.

Core Code Method of

Dating

Depth (cm)

Calibrated age (cal yr BP)

Age in ky (thousand years before present,

2005)

Source

0.125 0.00 0.00 0.38 4.01 0.00401 (2001 AD) 0.625 8.59 0.00859 0.875 15.21 0.01521 1.125 21.50 0.02150 1.375 27.34 0.02734 1.625 32.36 0.03236 1.875 43.16 0.04316 2.125 57.11 0.05711 2.375 70.06 0.07006 2.625 81.75 0.08175 2.875 100.26 0.10026

210Pb

3.125 120.78 0.12078 (1884 AD) 5.875 860 ± 64 0.860

05-CF8-SC

14C 16.875 2810 ± 20 2.810

Thomas et al. 2008

2 695 ± 35 0.695 ± 0.035 Axford et al. 2008 31 3140 ± 60 3.140 ± 0.060 50 4660 ± 40 4.660 ± 0.040

Briner et al. 2007a

58 7025 ± 125 7.025 ± 0.125 66.5 8295 ± 85 8.295 ± 0.085 70.5 8260 ± 70 8.260 ± 0.070 71 8185 ± 155 8.185 ± 0.155 77 8480 ± 60 8.480 ± 0.060 84 9410 ± 75 9.410 ± 0.075 88 9375 ± 115 9.375 ± 0.115 98 10300 ± 75 10.300 ± 0.075

Axford et al. 2008

107 10490 ± 190 10.490 ± 0.190 Briner et al. 2007a 107.5 10590 ± 85 10.590 ± 0.085

02-CF8-01 14C

113 11965 ± 140 11.965 ± 0.140 Axford et al. 2008

80 43000 ± 1070 43.000 ± 1.070 * 04-CF8-02 14C 81 34290 ± 570 34.290 ± 0.570 90-95 97150 ± 910 97.150 ± 0.910 90-95 105350 ± 9850 105.350 ± 9.850

* 05-CF8-01 OSL

140-145 121710 ± 12080 121.710 ± 12.080 05-CF8-01 OSL 213-218 >194120 ± 18920 >194.120 ± 18.920

Briner et al. 2007a

20

Figure 1a.

20

21

Figure 1b.

22

Chapter 3

Results

3.1 Core Characteristics and Chronologies

The multiple cores from Lake CF8 are composed of alternating units of stratified organic-

rich mud (gyttja) and medium- to coarse-grained sand. Organic sedimentation indicates

productive limnological and catchment conditions, including ice-free periods, and the sand units

denote regional or local deglaciation. A detailed model of sedimentation, as well as a lithological

description of the cores, is described by Briner et al. (2007a). The gyttja units of each core were

used for analysis and are described here. The surface sediment core (05-CF8-SC), which contains

late-Holocene sediment deposition, spans 45 cm and was sectioned at 0.25 cm resolution to 25

cm depth and 1.0 cm resolution thereafter. The core that spans the Holocene (02-CF8-01) is

approximately 121 cm in length and was sectioned at 1 cm resolution from the core depth of 5 cm

to 121 cm (the top 5 cm were disturbed during recovery). Based on two age models developed

using the radioisotopes 210Pb and 14C for the surface core (Thomas et al. 2008; Appendix G) and

14C for the Holocene core (Axford et al. 2008; Appendix H), the top interval of Holocene

sedimentation likely overlaps with 5 cm to 6 cm depth in the surface core. The LIG interstadial

sediments (contained in core 06-CF8-P1) were sectioned at 1 cm intervals for a total of five non-

continuous samples. The LIG sediment core (04-CF8-02) is 69 cm in total length and was

sectioned at 1 cm resolution from the core depth of 10 cm to 79 cm. The MIS 7 sediment core

(05-CF8-01) spans 24 cm in length, sectioned at 1 cm resolution from the core depths of 199 cm

to 223 cm.

Multiple methods for dating lacustrine sediments have been employed for the length of

the CF8 sediment record. Table 2 summarizes all dates obtained, including the estimates of

23

uncertainty assigned by the corresponding authors. The surface core (05-CF8-SC) represents the

late Holocene, and was dated using two radioisotopic techniques, 210Pb with the constant rate of

supply model, and radiocarbon dating, which facilitated the development of an age model to

characterize the ages of each interval (Appendix G). The uppermost sediments date at 2005 AD,

with unsupported 210Pb to a midpoint depth of 3.125 cm and an age of approximately 1885 AD.

Two radiocarbon ages were attained from aquatic moss, 0.86 ka at 5.875 cm and 2.91 ka at

16.875 cm midpoint depth. The calibrated age at the base of the diatom analysis for the surface

core is 3.30 ka. Axford et al. (2008) published all radiocarbon dates for the Holocene core, which

show that the sediments are largely chronologically stratified. The dates were obtained from

aquatic bryophyte macrofossils, which have been shown to calibrate with atmospheric CO2 in this

region (Wolfe et al. 2004). The top of this core (2 cm) dates at 0.69 ka, and the lowest reliable

date obtained (113 cm) is 11.97 ka. The interval 121 cm, the base of the core, dated at 9.51 ka. A

polynomial model was fit to the data, excluding the inverted date from 121 cm (Axford et al.

2008; Appendix H); Axford et al. (2008) therefore consider the model reliable to a depth of 107.5

cm, or 10.60 ka.

Table 2 shows a series of dates from two cores, 04-CF8-02 and 05-CF8-01, that position

their respective gyttja units within an interstadial and the LIG. These dates were not obtained

from the cores used for diatom analysis, though the gyttja units between cores are considered

directly comparable and have thus been assigned approximate ages. Two radiocarbon dates of

43.0 ka and 34.3 ka were obtained from a small section of organic mud with multiple moss

fragments. These dates are not chronologically ordered and approach the limit of finite 14C

dating; in this context, this gyttja unit likely lies within an interstadial older than 40 ka but

younger than the LIG sensu stricto, or MIS 5e. Briner et al. (2007a) employed optically-

stimulated luminescence (OSL) dating on the fine-grained polymineral and quartz fractions of

three intervals in a gyttja unit below the interstadial, indicating dates within the LIG including

24

97.2 ka to 121.7 ka. Full methodological details may be found in that paper. OSL dating was

also employed for the deepest gyttja obtained, indicating an age of >194.1 ka, within MIS 7, for

the sediments from 213 cm to 218 cm. General agreement exists that the entire gyttja record of

MIS 7 was not obtained, and has been limited only by coring equipment.

Increasing sediment density occurs with depth in the full CF8 sediment record. Figure 2

shows density (g/cm3) in relation to core depth for each core representing the late Holocene,

Holocene, an interstadial, the LIG, and MIS 7. Approximately every second interval was

measured for density. Density increases progressively through the surface core from 0.09 g/cm3

to 0.15 g/cm3. Through the depth of the Holocene core, density increases steadily until the basal

units, where a sharp rise in density occurs to 0.88 g/cm3. Two measurements in the interstadial

gyttja indicate densities of 0.91 g/cm3 and 1.42 g/cm3. The trend in density though the LIG is not

steady, though increases from the upper to lower intervals from approximately 0.59 g/cm3 to 0.96

g/cm3. The MIS 7 sediments have the highest densities from 1.16 g/cm3 to 1.66 g/cm3.

3.2 Diatoms

A total of 123 diatom species, from 36 genera, were encountered throughout the multiple

cores (Appendices B to F). Figure 3 shows the percent relative abundances (a typical measure of

the percentage that each species comprises of the total number of diatom valves enumerated per

interval) of species that appear at greater than 5 % abundance in at least one interval, plotted

against core depth. A total of 35 taxonomic groups or individual species are shown. The DIpH

and DCA Axis 1 scores are also displayed in Figure 3. The stratigraphy may be visually divided

into zones, based upon distinct shifts in the diatom assemblages, for ease of description. Zone 1

represents the top of the surface core, or late Holocene sediments, and Zones 2 and 3 indicate

25

Holocene sedimentation. The LIG interstadial is shown as Zone 4, and the LIG has been divided

into zones 5 and 6. MIS 7 is shown as Zone 7.

3.2.1 Zone 1 (05-CF8-SC, 0 cm to 19.625 cm, 2005 AD to ~ 3.30 ka)

In the uppermost strata from Lake CF8, the diatom assemblages are characterized by the

dominance of the heavily-silicified planktonic Aulacoseira group, primarily A. distans but also

including A. alpigena and A. perglabra, to a maximum of 60% abundance. It should be noted

that A. distans consists of the varieties distans and nivalis; considerable effort was made to divide

the group into varieties, though too much morphological overlap occurred between the varieties

to accurately separate this taxon. The dominance of Aulacoseira species is consistent throughout

this Zone, with a minimum combined relative abundance of 39%. A greater diversity of benthic

and epiphytic taxa, notably Psammothidium marginulatum, P. helveticum, Encyonema

gaeumannii, E. hebridicum, Eunotia exigua, Fragilariforma virescens, Frustulia saxonica,

Kobayasia subtilissima, and Pinnularia biceps, occurs in this zone (Figure 3). P. marginulatum

is consistently present at abundances between 8% and 25%. The relative abundance of E. exigua

increases through this zone, with a peak in the top 2 cm to approximately 16% relative

abundance. A combined group of benthic Fragilaria sensu lato taxa, including F. virescens,

Pseudostaurosira brevistriata and Staurosirella pinnata/Staurosira construens v. venter complex,

reach a maximum of 15% close to the base of Zone 1 (17.125 cm), gradually decreasing towards

the surface (Figure 3). The DIpH ranges from 5.95 to 6.17, capturing a relatively steady decline

towards the uppermost intervals of Zone 1. DCA Axis 1 sample scores varied similarly. N2

values varied between approximately 10 and 15, not synchronously with either DIpH or DCA

Axis 1 sample scores. The Hill’s N2 diversity statistic must be interpreted with caution, as both

the sampling resolution and the density of intervals are not consistent throughout the length of the

CF8 record, and thus N2 values may not be directly comparable between cores (Smol 1981).

26

3.2.2 Zones 2 and 3 (02-CF8-01, 5 cm to 121 cm, ~ 0.87 ka to > 11.97 ka BP)

Zones 2 and 3 represent Holocene sedimentation, which overlaps with the base of Zone

1; however, a conclusive overlap point has not been determined, and thus Zone 1 is presented

separately. The 2 cm interval has a date of 0.69 ka, though diatom analysis did not commence

until 5 cm (~ 0.87 ka) due to disturbance of the upper 5 cm. The lowest reliable date obtained, at

113 cm, is 11.97 ka (Axford et al. 2008); however, diatom analysis continued to the base of the

core at 121 cm.

Two designated zones occur within the Holocene: Zone 2, dominated by Aulacoseira

species, and Zone 3, primarily composed of Fragilariforma virescens. Zone 2 was delineated

based on the pronounced shift in Aulacoseira abundance at 78.5 cm depth, which corresponds to

an approximate age of 8.70 ka based on the polynomial age model developed by Axford et al.

(2008), and dominance through the upper portion of the core. The Aulacoseira group consists

mainly of A. distans v. distans, which reached a combined maximum relative abundance of 69%,

though A. perglabra reached a maximum relative abundance of approximately 7%. The

Aulacoseira group increased sharply in relative abundance at the onset of Zone 2 (78.5 cm),

where F. virescens abundance concurrently declined. The percentage of F. virescens furthermore

decreased through Zone 2 towards the top of the core. Psammothidium marginulatum gradually

increased through Zone 2, peaking at the top of the Zone (5.5 cm depth) at 31% relative

abundance, while Aulacoseira concurrently declined to its lowest relative abundance (at 5.5 cm)

within this Zone at 20%. Additional benthic taxa occur within Zone 2 at lower abundances than

the dominant Aulacoseira. Pinnularia biceps is consistently present through Zone 2, with an

approximate average of 7% abundance until the top 20 cm where the average abundance falls to

3%. Frustulia rhomboides, F. saxonica, Kobayasia subtilissima, and Neidium affine occur

regularly at low abundances. DIpH ranges from 6.48 to 5.96, decreasing through Zone 2, while

DCA Axis 1 sample scores also consistently declined.

27

Zone 3 represents the early Holocene, from approximately 11.49 ka at 120.5 cm (based

on the age model in Axford et al. 2008, although the model and dates may not be reliable at this

depth) to 8.70 ka at 78.5 cm. The assemblages in this Zone are dominated by F. virescens with a

sharp peak (from 108.5 cm to 113.5 cm) in S. pinnata/S. construens v. venter complex (Figure 3).

The Fragilaria sensu lato group reaches a maximum relative abundance of 93% (at 114.5 cm) in

Zone 3, and remains consistently dominant with a minimum abundance of 43% and an average of

68%. A short-lived peak in Nitzschia perminuta, to a maximum of 17% relative abundance,

concurrent with smaller rises in Cavinula variostriata and Navicula digitulus, characterize the

base (from 115.5 cm to 120.5 cm) of this Zone. P. marginulatum and Achnanthes curtissima also

appear with consistency, although A. curtissima is not present at the base of Zone 3. The

presence of Tabellaria flocculosa in this Zone, though in low relative abundances, is unique in

the Holocene record. DIpH peaks at the bottom of Zone 3 at 7.31 and declines inconsistently to a

minimum of 6.63; DCA Axis 1 sample scores reflect the fluctuating DIpH. N2 values fluctuate

from approximately 5 to 18 through Zones 2 and 3, and appear to have an approximately inverse

relationship to DIpH.

3.2.3 Zone 4 (06-CF8-P1, 94 cm to 107cm, ~ 35 ka, 45 ka)

The diatom analysis of Zone 4 represents five intervals within the LIG sensu lato

interstadial. The diatom assemblages in this Zone are dominated by Psammothidium

marginulatum at abundances of 53% to 62% (Figure 3). Fragilariforma virescens appears with a

maximum relative abundance of 23%. Tabellaria flocculosa and Stauroneis anceps are also

present, and fluctuate through the five intervals. In contrast to all other sections of the CF8

record, Aulacoseira does not constitute a majority in this Zone, reaching a maximum of

approximately 12% abundance in two intervals. The DIpH values show a consistent

28

reconstruction of pH 6.2 through this Zone, while DCA Axis 1 sample scores vary from 0 to 0.90.

N2 ranges from approximately 7 to 10.

3.2.4 Zones 5 and 6 (04-CF8-02, 10 cm to 79 cm, including ~ 97.15 ka to 121.71 ka)

Zones 5 and 6 represent LIG sedimentation. The Zone 5 to 6 transition at 66 cm depth

was identified due to the shift in dominance from Aulacoseira species to Fragilaria sensu lato

species (Figure 3). While this distinction is not as clear as that between Zones 2 and 3, this

taxonomic shift is an important feature of these interglacial sediment records and is thus

delineated for the purpose of comparison. Zone 5 is characterized by a lack of diatoms in the

uppermost sediment intervals from 10 cm to 13 cm. The upper intervals that contain diatom

fossils are initially composed primarily of Psammothidium marginulatum, from 43 % to 70 %

abundance (from 14 cm to 21 cm), leading into dominance but considerable fluctuations of the

Aulacoseira group of species below 22 cm depth. The total combined relative abundances of the

Aulacoseira group ranges from 3% to 83%; the declines in Aulacoseira apparently correspond

with parallel increases in P. marginulatum. Furthermore, variability exists within the Aulacoseira

group, with a pronounced peak of A. lirata from 47 cm to 65 cm (peak at 60 cm of 42% relative

abundance), which does not occur elsewhere in the CF8 sediment record. Tabellaria flocculosa

constitutes a variable but consistent component of the overall assemblages throughout this unit; T.

flocculosa does not appear at greater than 11% elsewhere in the CF8 sediment record, and peaks

at 52% relative abundance in the LIG sediments. Consistent with the highly variable diatom

assemblages of Zone 5, DIpH ranges from 5.9 to 7.0, and the DCA Axis 1 sample scores track the

DIpH fluctuations.

Zone 6 represents the initial sedimentation of the LIG (Figure 3). Fragilariforma

virescens peaks in the basal unit (79 cm interval) with a maximum relative abundance of 64%,

and steadily declines as the abundance of Pseudostaurosira brevistriata increases to a short-lived

29

peak (from 74 cm to 64 cm) from 11% to 60%. T. flocculosa also increases sharply in the base of

Zone 6 (76 cm), temporally lagging the maximum of F. virescens. The DCA Axis 1 sample

scores correspond to the fluctuations in DIpH, which ranges from approximately 6.9 to 6.4.

Throughout Zones 5 and 6, N2 ranges from approximately 8 to 20, with a peak at 33 cm depth. A

trend relating N2 to either DIpH or DCA Axis 1 samples scores is not clear.

3.2.5 Zone 7 (05-CF8-01, 199 cm to 223 cm, >194.12 ka)

Zone 7 represents sedimentation from a portion of MIS 7. Diatoms were not present in

sufficient quantities to enumerate from 199 cm to 202 cm; furthermore, the sediments of this

Zone required significantly less dilution compared to the Holocene and LIG sediments, indicating

that the concentration of diatom fossils was lower in the MIS 7 sediments. Despite the age of

these diatom fossils, dissolution was rarely evident under light microscopy, although scanning

electron microscopy images did reveal some etching of the valve surfaces.

The diatom assemblages of Zone 7 are dominated by Aulacoseira species, to a maximum

abundance of approximately 76% in the lowest interval (223 cm). Psammothidium marginulatum

increased in abundance towards the surface of this Zone, reaching a maximum of 47% relative

abundance at 207 cm. Similarly, P. helveticum group sharply increased in the upper intervals

though was not present in all intervals. Eunotia rhomboidea peaked at 9% relative abundance in

the 207 cm interval. Frustulia rhomboides was present at consistently low abundances, between

2% to 4%, though increased to 7% abundance in the uppermost interval (203 cm). Pinnularia

biceps abundance fluctuated through Zone 7 between 40% and 1%. DIpH varied from 5.8 to 6.3,

while the DCA Axis 1 sample scores fluctuated inconsistently in relation to DIpH. N2 values

were also inconsistent in relation to either DIpH or DCA Axis 1 sample scores.

30

3.3 Spectrally-Inferred Chlorophyll a

Spectrally-inferred chlorophyll a concentrations (mg/g dry weight) through the length of

the CF8 sediment record are shown in Figure 4, plotted as deviations from the mean value of all

core sections, with 0 representing the overall mean. This strategy for showing the chlorophyll a

concentrations in relation to the overall mean is due to some negative values in MIS 7, which

theoretically cannot be plotted and indicate very low or zero concentrations of chlorophyll a and

its degradation products. An arbitrary depth scale was used to plot all data on one figure, in order

to facilitate a comparison between the cores; a space of 10 cm was left between cores to provide a

visual separation of the data. Chlorophyll a reaches a maximum in the upper 1 cm of the surface

core, which represents sedimentation from approximately 1990 AD. Comparable chlorophyll a

concentrations occur earlier in the Holocene at 22.5 cm depth (~2.50 ka), as well as at the base of

the Holocene section (116.5 cm to 119.5 cm depth, ~11.25 ka to 11.41 ka BP). Fluctuations in

inferred chlorophyll a occur throughout the mid Holocene occur from approximately 0.04 mg/g to

-0.02 mg/g in relation to the mean. During the LIG, chlorophyll a concentrations are less than the

Holocene, and MIS 7 concentrations are below those of LIG. Chlorophyll a concentrations from

the interstadial sediments are not available.

31

3.4 Figures

3.4.1 Captions

Figure 2. A profile of the density (g/cm3) measured through each sediment core, shown against individual core depths. Figure 3. A stratigraphic profile of the percent relative abundances of the dominant (>5% relative abundance in at least one interval) diatom taxa throughout five sediment cores encompassing the surface. Holocene, interstadial, LIG and MIS 7 sediment sequences. Depth (cm) on the y-axis refers to individual core depths. The approximate location of dates is also shown. The x-axis indicates relative abundance; each unit represents 10% relative abundance. Diatom-inferred pH, DCA Axis 1 sample scores and Hill’s N2 numbers are also shown through depth. Zones 1 through 7 are indicated on the right, separated by sand units or indicated by a solid horizontal line. Figure 4. Spectrally-inferred chlorophyll a concentrations (mg/g dry weight), shown on the x-axis as deviation from the overall mean (a value of 0), through the surface, Holocene, LIG and MIS 7 cores. The y-axis represents an arbitrary depth scale (cm) that was used to plot these data, which originate from multiple cores, on one figure. The separation of each core is indicated. The legend indicates the data from each core.

32

Figure 2.

33

33 Figure 3.

34

Figure 4.

35

Chapter 4

Discussion

The sediment record from Lake CF8 offers a unique opportunity to examine several

paleolimnological questions throughout a long lake history spanning multiple interglacial periods.

This chapter aims to use the diatom data presented in Figure 3 to analyze several key questions

that have emerged concerning the late Quaternary limnological, environmental and climatic

development of this site, including: 1) characteristic patterns of lake ontogeny, as inferred by the

response of the diatom community, appear evident throughout each interglacial and are

comparable between interglacials; 2) the relationship between pH and climate, a purported

connection on Baffin Island and elsewhere, can be examined in light of the CF8 DIpH; 3) the

limnological changes associated with anthropogenic-induced warming of the late-Holocene may

be examined and compared to the environments of past warm periods, although the resolution of

each record differs and thus only general trends between interglacials can be discussed.

The diatom record from Lake CF8 indicates that similar ecological patterns, inferred

through characteristic diatom assemblage shifts, occurred during successive warm periods at this

site. The early Holocene sedimentation, shown in Zone 3 of Figure 3, was dominated by the

colonial benthic Fragilariforma virescens, with a distinct mid-Holocene shift in Zone 2 to a

planktonic assemblage dominated by Aulacoseira distans concurrent with a progressive increase

in the relative abundance of Psammothidium marginulatum and declines in DIpH. Similarly, the

early LIG, Zone 6 (Figure 3), reflects a dominance of F. virescens, and a clear shift to

assemblages largely composed of A. distans and other Aulacoseira taxa in Zone 5, where a sharp

rise in the abundance of P. marginulatum and a DIpH decline occurs. Furthermore, late MIS 7

sedimentation, partially captured in Zone 7, shows a diatom community dominated by A. distans

36

and increases of P. marginulatum towards the top of this core. These apparent, climate-driven

interglacial trends will be discussed through a comparison of the ecological interpretation of each

gyttja unit throughout the entire Lake CF8 record. For Arctic lakes, climate effects are largely

manifested through changes in the duration of lake ice cover (Smol 1983, 1988), which in turn

influences habitat type and availability for diatom colonization (Douglas and Smol 1999; Smol

and Douglas 2007b). Therefore, the relationship between the diatom assemblages in the CF8 lake

record will be interpreted in relation to climate and habitat.

In addition, a pattern of changes in lakewater DIpH, possibly related to climate, has been

identified in several paleolimnological records on Baffin Island (e.g. Wolfe 2002; Michelutti et al.

2007). While pH is clearly an important driver of diatom assemblages in Lake CF8 (Figure 3,

DCA Axis 1 sample scores), the recent pH of the lake has not responded as expected in relation to

an Arctic climate-pH model (Michelutti et al. 2007). The relationship between DIpH and climate

at Lake CF8 will be compared to other lakes on Baffin Island.

Post-Little Ice Age warming is known to influence Arctic lakes, which in turn often

affects the diatom community in characteristic ways (Smol and Douglas 2007b). The uppermost

sediment units of the Lake CF8 record show a diatom response similar to some high Arctic

lacustrine systems (e.g. Michelutti et al. 2006; Smol et al. 2005), and may also be comparable to

other lakes on Baffin Island (Briner et al. 2006; Wolfe et al. 2006a) and the Finnish Lapland

(Sorvari et al. 2002). The modern diatom response to a changing climate may also be interpreted

with respect to the other interglacial periods preserved in this sediment record; one of the distinct

advantages of this long sediment record is the contextualization of the current Arctic climate.

4.1 Patterns of Diatom-Inferred Lake Development Throughout Each Interglacial Period

The general diatom flora of Lake CF8 remained relatively consistent throughout all gyttja

units, and is characteristic of dilute lakes on Baffin Island (e.g. Joynt and Wolfe 2001; Miller et

37

al. 1999; Wolfe 1996; Wolfe et al. 2000) and other lakes located on the crystalline geology of the

Canadian Shield (e.g. Grönlund et al. 1989). The overall assemblage contains a higher diversity

of benthic taxa compared to planktonic species, which is typical of relatively shallow Arctic lakes

and is indicative of expansive ice cover that precludes extensive planktonic communities (Smol

and Cumming 2000). Species diversity, indicated in Figure 3 as Hill’s N2, encompasses both

richness and evenness; though the N2 values are not directly comparable between cores due to

differing sampling resolution and density (Smol 1981), diversity is highest in the LIG sediments

and lowest in MIS 7.

4.1.1 The Holocene Interglacial

Sedimentation spanning the early Holocene from deglaciation and subsequent active

biological lake conditions to approximately 8.70 ka, shown as Zone 3 (Figure 3) is dominated by

Fragilariforma virescens as well as a short-lived peak of Staurosirella pinnata/Staurosira

construens v. venter complex, which combined, reach up to 93% relative abundance. The

Fragilaria sensu lato group, composed of five genera (Round et al. 1990), is recognized as an

early colonizer of newly formed or deglaciated lakes in various regions of the world, particularly

in Arctic lakes (e.g. Douglas and Smol 1999; Lemmen et al. 1988; Pienitz et al. 2004; Smol

1983). The pioneering nature of these genera may be attributed to multiple autecological

characteristics: a high surface to volume ratio allows small fragilarioid taxa to be competitive in

nutrient limiting conditions (e.g. Lotter et al. 1999), and in general small Fragilaria species are

benthic, living loosely attached to surfaces including sediment, and circumneutral to slightly

alkaliphilous, and therefore flourish in environments with cold water temperatures, prolonged ice

cover, and enhanced catchment erosion (Ampel et al. 2008; Douglas and Smol 1999; Haworth

1976; Lotter and Bigler 2000; Rioual and Mackay 2005; Smol 1983). Some researchers also

describe Fragilaria species as cosmopolitan in relation to its range of environmental tolerances,

38

which may contribute to the dominance that has been noted in low diversity assemblages (e.g.

LeBlanc et al. 2004; Podritske and Gajewski 2007). Joynt and Wolfe (2001) report an optimum

pH of slightly acidic to circumneutral for F. virescens, S. pinnata and S. construens v. venter on

Baffin Island. Nitzschia perminuta also appears briefly in the early Holocene, concurrent with

small peaks in Navicula digitulus and Cavinula variostriata. Pinnularia biceps, Psammothidium

marginulatum, and Tabellaria flocculosa also appear with consistency. The presence of these

benthic species, also with slightly acidic optima (Joynt and Wolfe 2001), concurrent with low

species diversity (low Hill’s N2 values), may similarly indicate that while littoral habitat was

becoming available at this lake, perhaps at the edges of a partially ice covered lake (Smol 1983,

1988), conditions were still not generally favourable for a complex diatom community.

Ecologically, the dominance of a circumneutral, benthic, cold water diatom assemblage,

which persisted at high relative abundances until approximately 8.70 ka, indicates that prolonged

ice cover and limited planktonic habitat was available immediately following deglaciation and

into the early Holocene at Lake CF8. The early Holocene is typically documented as the warmest

period of the epoch across the Arctic and North America (e.g. Briner et al. 2006; Dyke et al.

1996; Koerner and Fisher 1990; Viau et al. 2006), driven by higher insolation in the early

Holocene (Berger and Loutre 1991), although the early Holocene is recognized as a period

characterized by spatially inconsistent climatic fluctuations (e.g. Johnsen et al. 2001). Axford et

al. (2008) constructed a high-resolution paleotemperature record from fossil chironomid remains

throughout the Holocene at this site, and indicated that while summer temperatures were cold

initially following the glacial period, a maximum was reached by 10.5 ka BP, warmer than today

(Axford et al. 2008). However, Briner et al. (2007b) reconstructed the deglaciation of Clyde

Inlet, a fiord in the Clyde Foreland, and found evidence of two glacial advances between 8.5 ka

and 7.9 ka, with moraines deposited as late at 8.4 ka. Axford et al. (2008) found similar cold

reversals at Lake CF8, indicated by the presence of cold stenothermous chironomid taxa, between

39

9.0 ka and 8.5 ka. Reconciling data that suggests early Holocene warmth with the apparent cold,

ice-covered environment indicated by the diatom record is challenging. A noticeable increase in

diversity at approximately 10.4 ka occurs in the diatom data, which may approximately correlate

with the slight increases of some benthic taxa (such as Encyonema gaeumannii and P.

marginulatum), indicating increased benthic habitat availability caused by a longer growing

season and thus warmer summer temperatures. However, the use of diversity indices is not as

indicative of environmental shifts as the specific changes in the diatom assemblage composition,

and the diatom shifts at 10.4 ka are low in amplitude in relation to the rest of the Holocene record.

Ultimately, the evidence for multiple glacial advances and cold periods within the lake prior to

8.5 ka, accompanied by the diatom-inferred post-glacial environment at Lake CF8, may infer that

regional advances of the LIS exerted climatic influence into the early Holocene, even with the

regional warming trend.

A clear transition in the diatom community occurred at approximately 8.70 ka with a

distinct increase in the abundance of Aulacoseira distans, which, combined with A. perglabra,

reached approximately 70% relative abundance, and a parallel decline in Fragilaria taxa, shown

in Zone 2 of Figure 3. The diversity of planktonic species is typically low across Baffin Island

(Joynt and Wolfe 2001), as was found in the Lake CF8 record. A. distans persisted as the primary

diatom taxon throughout the rest of the Holocene sedimentation, while A. perglabra reached only

low abundances. This assemblage represents a markedly different diatom community and likely

limnological regime compared to the early Holocene. A. distans is an acidophilous

tychoplanktonic species that is heavily silicified and requires open, somewhat turbulent, water to

dominate (e.g. Joynt and Wolfe 2001; Miller et al. 1999; Van Dam et al. 1994; Wolfe and

Härtling 1996). The prevalence of A. distans may be interpreted as representing an ameliorated

climate in relation to the early post-glacial environment. From approximately 8.7 ka to the top of

Zone 2 (Figure 3), approximately 0.9 ka, progressive lake development likely occurred with ice-

40

free summers, an open planktonic habitat and a developed littoral habitat zone. F. virescens

remained present, although declined throughout the Holocene; almost synchronously, P.

marginulatum increased in abundance. Several other species, including Encyonema gaeumannii,

Eunotia rhomboidea, Frustulia rhomboides, F. saxonica, Neidium affine, and P. biceps, occurred

consistently at low abundances throughout Zone 2 (Figure 3). These benthic species indicate that

as the Holocene progressed, substrates became available for periphytic growth; for example, the

littoral region of the lake was likely occupied by moss growth providing epiphytic substrates, and

benthic epipelic and epilithic substrates were available for diatom colonization due to light

penetration. This more diverse diatom assemblage, with planktonic, benthic and epiphytic

species, indicates a warmer climate that allowed a more complex habitat structure (Douglas and

Smol 1995). Hill’s N2 diversity values are higher in Zone 2 of the mid- Holocene compared to

Zone 3, the early Holocene, which reflects this enhanced benthic habitat.

The peak temperatures of the Holocene appear to have varied temporally and spatially.

For example, the first ~ 2 ka of the Holocene is often discussed as the warmest of the epoch (e.g.

Briner et al. 2006; Koerner and Fisher 1990; Viau et al. 2006), while Francis et al. (2006) have

inferred that the first half of the Holocene was warm with progressive cooling thereafter. Other

authors have identified a mid-Holocene climatic optimum from 6 ka to 3 ka, which may have

been warmer than present at Clyde River (e.g. Kerwin et al. 2004; Williams and Bradley 1985).

Though the timing of peak warmth may have varied across Baffin Island (Briner et al. 2006), in

general, this warming may be temporally correlated with the rise in abundance of A. distans after

8.70 ka due to decreased summer ice cover which provides open planktonic habitat (e.g. Smol

1983, 1988). Regional cooling after ~ 3 ka, leading into the late-Holocene Neoglaciation (e.g.

Kerwin et al. 2004; Levac et al. 2001; Miller 1973; Miller et al. 2005; Wolfe 2003), may be

indicated in the diatom response in the upper portion of Zone 2 (Figure 3). P. marginulatum

increased to approximately 30% relative abundance in the upper sediments of Zone 2, concurrent

41

with a small increase in Eunotia bilunaris, as a decline in A. distans occurred. This diatom shift

may infer longer ice cover through the warm season with less planktonic habitat availability but

consistent littoral habitat. Wolfe (2003) suggested that increased diatom diversity can be related

to a colder climate with increased ice cover, indicating fragmentation of the littoral habitat, the

inability of opportunistic taxa to dominate, and thus a larger diversity of benthic taxa.

Sediment records from other Baffin Island lakes have indicated that similar diatom

communities and the transition from Fragilaria sensu lato to Aulacoseira throughout the

Holocene have occurred regionally. For example, the post-glacial diatom assemblage at

Robinson Lake on southeastern Baffin Island was dominated by F. virescens with low, consistent

abundances of the periphytic T. flocculosa until approximately 7.5 ka, when Aulacoseira species

increased in abundance to become the dominant taxon (Miller et al. 1999). In addition, the

Robinson Lake diatom record contains benthic Achnanthes (which, in the present study, includes

Achnanthes, Achnanthidium and Psammothidium), Frustulia, and Navicula (includes Navicula,

Cavinula, and Kobayasia) species through the mid- to late-Holocene (Miller et al. 1999). The

similarities of the Robinson Lake Holocene diatom stratigraphical record are evident and striking

compared to Lake CF8, indicating that similar climatic conditions prevailed across eastern Baffin

Island throughout the Holocene and impacted both lakes analogously, likely through the

moderating effects of lake ice. Alternatively, the establishment of vegetation and catchment

stabilization occurred by approximately 8 ka across most of Baffin Island (e.g. Kerwin et al.

2004; Miller et al. 1999), which may have contributed to the marked shift in the diatom

communities evident at both Robinson Lake and Lake CF8. The Holocene basal gyttja from two

lakes, Amarok and Tulugak, on Cumberland Peninsula also indicated an early spike in Fragilaria

species, followed by a progressive increase in the abundances of benthic and periphytic acidic

diatom species, including A. distans (Wolfe and Härtling 1996; Wolfe 1996). Fog Lake, another

site on Cumberland Peninsula, experienced the coldest conditions of the Holocene during the

42

post-glacial development of the lake, when benthic taxa including Fragilaria and Pinnularia

species dominated the community profile (Wolfe et al. 2000). Furthermore, while the distinct

diatom transitions found at Lake CF8 are not evident in the Fog Lake sediment record, A. distans

encompasses a significant portion of the mid-Holocene diatom community, concurrent with

benthic and periphytic species including E. gaeumannii, F. saxonica and P. biceps (Wolfe et al.

2000).

The occurrence of circumneutral to slightly alkaline species at the onset of the Holocene,

followed by a transition to acidophilous and often planktonic species, is relatively common across

Baffin Island (e.g. Miller et al. 1999; Wolfe and Härtling 1996). Interestingly, a comparison of

the CF8 Holocene diatom assemblages to nearby Lake CF3 on the Clyde Foreland shows fewer

similarities. Lake CF3 has similar physical and limnological characteristics to Lake CF8, other

than altitude (CF3 lies at 27 m asl, while CF8 is 200 m asl) (Briner et al. 2006). The diatoms in

the basal Holocene sediments at Lake CF3 indicate initially acidic conditions, with primarily A.

distans and Eunotia species (Michelutti et al. 2007). In the later Holocene, a transition from

Fragilaria sensu lato abundance to an increased diversity of benthic and planktonic species

occurs (Michelutti et al. 2007). The differences between lakes CF3 and CF8 in both the timing

and the magnitude of these shifts may be due to the altitude differences between these lakes.

Joynt and Wolfe (2001) determined that altitude is a better predictor of summer water

temperatures than latitude on Baffin Island. Lake CF8 lies over 150 m asl higher than CF3,

which is closer to the coast of Baffin Bay and likely experiences longer ice-free seasons (Briner,

personal communication). The transition between Fragilaria and Aulacoseira species dominance

occurred abruptly at 8.7 ka at Lake CF8, while at Lake CF3, the transition was more gradual

through the early- to mid-Holocene (Michelutti et al. 2007). The early Holocene climate was

progressively warming, and if Lake CF3 became ice-free during the gradual temperature

increases of the early Holocene, the diatoms may also have responded slowly. At Lake CF8,

43

however, ice-free conditions likely first occurred when the climate was already established and

warm, later than CF3, resulting in a rapid diatom response; this may indicate the importance of

the timing of LIS retreat in relation to the timing of maximum warmth. Therefore, the altitudinal

differences between lakes in this region may affect limnological characteristics at the scale of the

Holocene. In addition, the striking similarity of the CF8 Holocene record and the Robinson Lake

record (Miller et al. 1999) may also be partially explained by altitude, as both lakes are

approximately 200 m asl.

4.1.2 The Interstadial Sediments

An interstadial period reflects regional warm conditions that do not compare in length or

extent to a full interglacial, but signify ameliorated climate with respect to glacial periods. Zone

4 (Figure 3) likely represents an interstadial stage induced by regional ice sheet retreat, and may

occur within the LIG sensu lato. While the diatom analysis does not represent a temporally

continuous sequence, the intervals examined all contain large abundances of the acidic, periphytic

P. marginulatum, a consistent presence of F. virescens and the almost complete absence of

planktonic taxa. Stauroneis anceps, a circumneutral benthic diatom (VanDam et al. 1994), also

appears within these sediments, unique to this Zone compared to the rest of the CF8 record. The

dominance of benthic, periphytic diatoms, in particular P. marginulatum, an acidic moss epiphyte

(Joynt and Wolfe 2001; Wolfe 1996), is consistent with the direct observations of this section of

the CF8 core, which contained numerous moss fragments. The moss has been preliminarily

identified as Warnstorfia exannulata, a bryophyte common to Baffin Island lakes currently and as

fossils in sediment records (e.g. Miller et al. 1999; Wolfe et al. 2000; Wolfe, personal

communication). This moss often grows submerged (Miller et al. 1999), and may suggest lower

water levels during this period.

44

A similar gyttja unit with abundant moss fragments was found in Robinson Lake, dated at

approximately 43.1 ka (Miller et al. 1999, unit C). This unit contained sparse pollen (Miller et al.

1999), which may indicate that, like the interstadial gyttja in the Lake CF8 record, this unit was

deposited at a time when the regional climate was still cold and partially glaciated, limiting the

establishment of vegetation. The sediment record of Fog Lake also contained a moss unit

dominated by P. marginulatum (Wolfe et al. 2000), as well as several other periods of

intermittent sediment deposition before the onset of the Holocene epoch, attributed to interstadial

stages (Wolfe et al. 2000). The presence of interstadial sediment units, particularly those

containing characteristic intervals with abundant moss fragments, indicates that pre-Holocene

climatic fluctuations were common and affected widespread regions of the LIS on Baffin Island.

Furthermore, this unit of organic sedimentation may be conceptually regarded as a ‘cold

analogue’, as an interstadial period reflects colder temperatures than an interglacial, with

attendant terrestrial and limnological responses. Accordingly, the later Holocene, typically

regarded as a period that experienced cooling, also contains increasing concentrations of P.

marginulatum; however, the cold climate of the interstadial precluded diverse diatom

assemblages.

4.1.3 The Last Interglacial

The Last Interglacial sensu lato (LIG) diatom assemblages, representing sedimentation

from approximately 121.71 ka to 97.15 ka, are shown in Zones 5 and 6, and may be compared to

the Holocene interglacial shown in Zones 2 and 3 (Figure 3). The sediment density of each core,

shown to increase with increased depth (Figure 2), should be noted with respect to the physical

length of each gyttja unit, which does not indicate temporal length; the increasing density in the

lower gyttja units likely indicates compaction of the deeper sediments. Therefore, the LIG period

may be longer temporally than the Holocene, but is represented by a shorter gyttja unit (Figure 3).

45

Similar compaction has been found in other long sediment records. For example, the density of

interglacial sediments was twice that of Holocene sediments in the Robinson Lake sediment

record (Miller et al. 1999). In turn, this indicates that each sediment interval in the LIG captured

a longer time span than each interval in the Holocene; comparisons between interglacials thus

must be made with caution.

Zone 6, the base of sedimentation during this interglacial period, is composed primarily

of F. virescens with a sharp transition to T. flocculosa, succeeded by Pseudostaurosira

brevistriata. A. distans also appears within Zone 6. With a similar diatom profile as the base of

Zone 3, the ecological interpretation of the early LIG environment is comparable to the early

Holocene. The post-glacial lake conditions were likely similar: cold and largely ice covered, with

littoral habitat at the lake edges available for the development of F. virescens and the colonial,

periphytic T. flocculosa. The early LIG is reconstructed as more acidic than the early Holocene,

perhaps indicated by the peak in T. flocculosa, with a pH optimum of 6.6, though the subsequent

peak of P. brevistriata, with a pH optimum of 6.8, indicates fluctuating pH (Joynt and Wolfe

2001). Planktonic habitat may have been more established during the early LIG compared to the

early Holocene, as A. distans appears at low abundances at the same time as the dominance of

benthic taxa. However, as shown by Lotter and Bigler (2000) in an alpine lake, a low

concentration of planktonic taxa may indicate low water temperatures and a correspondingly cold

climate.

Zone 5 of the LIG (Figure 3) may also be comparable to Zone 2 of the Holocene. Both

sections are dominated by planktonic species, which decline in the upper intervals while P.

marginulatum increases. However, A. lirata appears only in the LIG at any appreciable

abundance, during which time A. distans declines in relative abundance. A. lirata is the heaviest

silicified species that occurs in lakes on Baffin Island, and therefore requires circulation to

46

maintain position in the water column (e.g. Miller et al. 1999). A. lirata may therefore be an

indicator of more vigorous catchment conditions and longer, warmer and wetter summer seasons

that supply greater concentrations of silica to the lake and allow more turbulence of the lake

(Miller et al. 1999). The overall diatom diversity in Zone 5 is similar to that of Zone 2, though

does not appear to follow any trend (see N2 values on Figure 3).

The climate of the LIG, driven by fluctuating insolation patterns (Loutre and Berger

2003), was likely more unstable (GRIP Members 1993) and warmer than any time during the

Holocene on Baffin Island and elsewhere in the Arctic (deVernal et al. 1991), as reconstructed

from past sea level (e.g. Koerner 1989) and paleoecological evidence such as elevated pollen

concentrations (e.g. Kerwin et al. 2004; Miller et al. 1999; Wolfe et al. 2000), the presence of

marine molluscs in terrestrial records (e.g. Miller et al. 1977), and chironomid-inferred July

temperatures (Axford 2007; Francis et al. 2006). Reconstructed summer air and water

temperatures have been shown to vary similarly through the LIG (Francis et al. 2006), indicating

that higher LIG air temperatures were transferred to the lake environment, possibly through the

dynamics of lake ice (Smol 1983). Furthermore, the lengths of the individual summer seasons

were likely longer than those of the Holocene (e.g. Fréchette et al. 2008; Miller et al. 1977). The

climate also provided more weathering of the bedrock at a lake on southeastern Baffin Island,

indicating more vigorous catchment conditions and wetter warm seasons during the LIG (Miller

et al. 1999). A warmer climate of longer duration in the LIG compared to the Holocene may

explain the variance in the diatom patterns between these interglacial periods. For example,

during the LIG, a greater diversity of planktonic species developed, including A. lirata that

appears only in the LIG and requires turbulent, open water, in addition to A. alpigena, A.

perglabra and A. distans. In addition, the LIG is the only period where Cyclotella bodanica, a

fully planktonic taxa, appears in the sediment record, albeit only at trace abundances.

Furthermore, several benthic species that appear in the Holocene constitute larger abundances in

47

the LIG, such as P. marginulatum and T. flocculosa (Figure 3), which may indicate even greater

benthic littoral habitat availability. Furthermore, the Greenland Ice Sheet melted extensively or

completely during the LIG (Koerner 1989), and Miller et al. (1999) suggest that the LIS may also

have deglaciated considerably across the eastern Arctic. During the early Holocene, regional ice

sheet advances likely impacted the development of Lake CF8, whereas if the LIS responded

similarly to the Greenland Ice Sheet during the LIG, the local effects of the LIS would have been

reduced in the LIG. These greater LIG temperatures and the potential of reduced effects from the

LIS may explain the differences in the diatom assemblages between the two interglacial periods.

As the regional climate descended into the penultimate glaciation at the end of the LIG,

Lake CF8 likely became increasingly ice covered, perhaps reflected in the declining abundance of

A. distans in the upper 5 cm of Zone 5 but the persistence and dominance of the benthic P.

marginulatum and T. flocculosa. The upper 3 cm of sediment, however, contain too few diatoms

for enumeration, perhaps indicating perennial ice cover and conditions not suitable for

phytoplankton growth. Chironomid-inferred temperatures from this lake also indicate significant

cooling following peak LIG warmth as the climate progressed towards glaciation (Axford 2007).

Several sediment records from across Baffin Island and elsewhere in the Arctic have

captured LIG sediment sequences. The interglacial gyttja unit from Lake CF8 is likely

comparable to the ascribed MIS 5 sediments from both Fog Lake (Wolfe et al. 2000) and

Robinson Lake (Miller et al. 1999) on southeastern Baffin Island. The Fog Lake sediment record

contains interglacial depositions underlain by mineral units, indicating that the entire LIG

sequence was attained (Wolfe et al. 2000). A spike in F. virescens marks the onset of the LIG,

similar to the CF8 record, though Aulacoseira species appear only sporadically. A distinct

feature of the Lake CF8 early LIG diatom stratigraphy is the co-occurrence of F. virescens and A.

distans with both at appreciable abundances, which does not happen in the early Holocene; this

also occurs in the Fog Lake record (Wolfe et al. 2000), as well as a diatom record from Lake

48

Baikal (Rioual and Mackay 2005), and may indicate that regionally warmer temperatures were

already established when this site was deglaciated (e.g. Axford 2007), perhaps suggesting a faster

transition from glacial to interglacial conditions in the early LIG compared to the early Holocene.

The sediment record of Robinson Lake contains gyttja units from multiple cores that are

representative of MIS 5 sediments (Miller et al. 1999), with a similar diatom profile comparable

to Lake CF8. While the Robinson Lake record did not penetrate the entire interglacial sequence,

Aulacoseira species are present throughout the interglacial gyttja with the co-occurrence of F.

virescens and alkaliphilous Fragilaria species, as well as benthic Achnanthes, Navicula and

Frustulia, common throughout (Miller et al. 1999). Interestingly, the heavily silicified A. lirata

also appeared only in the LIG sediments at this lake, which Miller et al. (1999) attribute to

intensified erosion from the catchment during the LIG compared to the Holocene. The

similarities between these records may indicate that the LIG climatic characteristics were

widespread across Baffin Island.

On a wider scale, the long sediment record from the crater lake El’gygytgyn in

northeastern Siberia, which spans ~ 250 ka (e.g. Cherapanova et al. 2007), did not clearly capture

MIS 5e in the diatom record, though multiple other warm periods were indicated. A low diversity

of planktonic species, at high abundances, was found to persist through the warm periods

captured (Cherapanova et al. 2007). Sediment records from Lake Baikal, also in Siberia, have

noted similar trends compared to Lake CF8: benthic species, including low abundances of

Fragilaria sensu lato species, were common in the basal sediments, planktonic taxa dominated

the middle of the interglacial period, and benthic species increased in abundance towards the end

of the period as conditions cooled and glaciation approached (Rioual and Mackay 2005).

49

4.1.4 MIS 7

Few records pertaining to the climate during MIS 7 are available, though Desprat et al.

(2006) characterized the significant climatic variability that occurred during this interglacial

epoch, which encompasses five warm/cold oscillations, similar to the LIG sensu lato. The Lake

CF8 record of MIS 7, while not complete, is comparable to the upper segments of both the

Holocene and LIG, and captures at least a portion of full interglacial conditions though likely the

waning stages (Axford 2007). A. distans is inconsistently the most abundant diatom taxa, though

large fluctuations in the relative abundance of this species occurs. Similar to the upper sections

of the LIG and Holocene, P. marginulatum increased in abundance as this interglacial period

progressed, concurrent with low abundances of benthic and periphytic species such as F.

virescens, P. biceps and Neidium and Frustulia species. The late MIS 7 likely resembled the

deteriorating climate of the LIG leading into glacial conditions. As temperatures declined,

increasingly prolonged ice cover limited planktonic habitat availability, while the littoral zone

likely remained ice-free in the warm seasons allowing benthic diatom species to persist.

Chironomid-inferred temperatures and diversity confirm these diatom inferences; Axford (2007)

found that chironomid diversity was lower in the MIS 7 sediments compared to the Holocene, and

suggests declining temperatures. In addition, while only a qualitative observation, the sediments

of MIS 7 contained far fewer diatom valves compared to the subsequent two interglacial periods,

indicating less production. The only other comparable diatom assemblage from Lake

El’gygytgyn in Siberia recorded high abundances of planktonic species during multiple warm

periods of the full MIS 7 interglacial, with persistent but low abundances of benthic and

periphytic diatom taxa (Cherapanova et al. 2007).

50

4.1.5 Trends Between the Three Interglacial Diatom Records

The pattern of interglacial lake ontogeny inferred by the diatom record indicates that

similar climatic trends likely occurred throughout each warm period, facilitating a characteristic

succession in the diatom community. The base of the Holocene and LIG both indicate a cold,

ice-covered lake allowing the colonial F. virescens to dominate littoral habitat. At some

threshold temperature, the lake transitioned to dominantly ice-free in the summer season,

indicated by high relative abundances of the tychoplanktonic A. distans. The early Holocene and

early LIG temperatures at Lake CF8 may have been comparable (e.g. Axford et al. 2008; Axford

2007), although the diatom data suggests that temperatures may have reached a maximum more

quickly in the early LIG, while early Holocene temperatures experienced a ‘ramp up’ following

deglaciation. The climate of each interglacial was steady enough to allow Aulacoseira species to

thrive and dominate for a significant portion of the interglacial period. Although the entire

sediment record of MIS 7 was not attained, the diatoms indicate that a portion of this warm period

was captured.

At the top of all three interglacial sediment sequences, a progressive decline in the

abundance of A. distans occurs, with a concurrent rise in P. marginulatum and other benthic

diatom taxa. Fragilaria does not return as the dominant group, because while this group

indicates cool, ice-covered conditions in the early Holocene and LIG, the pH of the lake towards

the end of each period is more acidic, likely precluding the return of the more circumneutral

Fragilaria taxa. The late-Holocene cooling of the Neoglacial period may be indicated by this

trend of increasing benthics in the diatom record. For the LIG and MIS 7, the diatoms likely

indicate the gradual cooling of the climate that would have occurred with impending glaciation,

which may be comparable to the Neoglacial cooling of the late-Holocene. The lack of diatom

valves in the upper units of these two cores further demonstrates the climatic deterioration at the

end of the interglacial periods. The striking similarities between the interglacial periods, as

51

expressed through the diatom record, indicate that the development of the lake following

deglaciation during these interglacials followed a common ontogenetic pattern. The past two

centuries, however, have initiated a new pattern in the diatom community (discussed in Section

4.3) not comparable to the upper sediments of either the LIG or MIS 7.

Spectrally-inferred chlorophyll a concentrations were measured throughout the length of

the CF8 sediment record to facilitate the comparison of the interglacials. However, no

discernable trend appears between the interglacial periods (Figure 4). The highest concentrations

occur at the base of the Holocene, the late-Holocene, and the uppermost sediments. The surface

core will be discussed in Section 4.3; however, the chlorophyll a peaks of the Holocene occur

during the coolest years of the epoch, the post-glacial and Neoglacial. In addition, as potentially

indicated through the Lake CF8 diatom record, as well as multiple other studies (e.g. Francis et al.

2006; Fréchette et al. 2006), the LIG was warmer in the Baffin Bay region compared to the

Holocene, which in turn could cause increases in primary production. However, the LIG

concentrations of the photosynthetic pigment chlorophyll a are on average lower than the

Holocene (Figure 4). The MIS 7 chlorophyll a trend, however, is indicative of the cooler climate

captured towards the end of the interglacial period. The spectrally-inferred method of

determining total chlorophyll a concentrations in lake sediments also measures the pigment

breakdown products, and thus is considered a robust indicator of total production through at least

the scale of the Holocene (Michelutti et al. 2005; Michelutti et al. 2009). Figure 4 indicates,

however, that perhaps on time scales beyond the Holocene, some degradation of the pigment and

the pheopigments does occur. Alternatively, because of the nature of these data (measured as

concentration), changing sedimentation rates have likely affected the chlorophyll a trends. For

example, the early Holocene peak in chlorophyll a may be indicative of low sedimentation rates,

which would effectively concentrate the chlorophyll a. Low sedimentation rates may be

anticipated during cold periods, with less aquatic and terrestrial productivity. Similarly, the late-

52

Holocene, which was colder than the mid-Holocene, also expresses high chlorophyll a

concentrations. However, the LIG does not show this trend, and may thus indicate that both

changing sedimentation rates and pigment degradation have affected this proxy indicator.

As discussed, these patterns of lake development can be understood through the influence

of changing temperatures on lake ice, and the effects of lake ice on the habitat of diatom

communities. Through the dynamics of lake ice, however, climate also impacts limnological

variables such as pH (e.g. Wolfe 2002; Michelutti et al. 2007). Habitat appears to be particularly

influential on the diatom communities of Lake CF8 in the early stages of the interglacial periods

and is likely the main driver of abrupt species changes. However, the succession of pH as related

to climate also clearly affects the diatom trends, and may be particularly important in determining

the specific species present in each habitat type.

4.2 Climate, DIpH, and Diatom Succession

The effect of pH on diatom communities is well established as a primary control over the

structure of diatom assemblages in this region (Joynt and Wolfe 2001; Michelutti et al. 2007) as

well as elsewhere in the Arctic (e.g. Fallu et al. 2000; Douglas and Smol 1999). Accordingly, the

diatom community at Lake CF8 responded to pH throughout at least the Holocene and LIG, as

shown in the close tracking of the DIpH by the DCA Axis 1 sample scores throughout these core

sections (Figure 3). When pH was regressed against DCA Axis 1 sample scores, the correlation

(r value) was high for the surface, Holocene and LIG (0.73, 0.96, and 0.81 respectively) sections,

though the correlation for the interstadial and MIS 7 sections was much lower (0.35 for both).

Overall, pH declined through each interglacial period (Figure 3), becoming more acidic with

time. The current pH of Lake CF8 is approximately 6.3, which is close to the DIpH of 6.0 in the

uppermost sediment interval. The diatom assemblages become more acidic towards the top of the

53

surface core; one of the striking changes is the increase in Eunotia exigua, which has a pH

optimum of 6.4 (Joynt and Wolfe 2001). A separate surface core obtained in 2008, which was

not analysed in detail for this study, also showed dominance by Eunotia species, primarily E.

bilunaris, which has a pH optimum of 6.5 (Joynt and Wolfe 2001). While this indicates some

spatial heterogeneity in the distribution of benthic species across the lake floor, three more years

of sedimentation show that Eunotia species are still the dominant benthic diatom taxon.

Many lakes in the Clyde Foreland region are currently slightly acidic and have low DIC

concentrations (Michelutti et al. 2005). For example, the pH of Lake CF3 under ice is 5.9

(Michelutti et al. 2007). The crystalline terrain of Baffin Island, which is slightly acidic, without

carbonate, makes these lakes poorly buffered against changes in pH (Miller et al. 1999; Wolfe

and Härtling 1996; Wolfe 1996). Typically, edaphic catchment processes are invoked as the

primary source of pH changes within lakes, through the weathering of bedrock and input of base

cations. For example, alkalinity is often higher following deglaciation, usually associated with

the input of glacial tills and sediment biogeochemical reactions (e.g. Renberg 1990; Wolfe and

Härtling 1996). Catchment erosion is also sometimes used to describe the prosperity of

Aulacoseira species that require high concentrations of silica (e.g. Miller et al. 1999; Wolfe and

Härtling 1996), though silica concentrations at Lake CF8 are currently not limiting (Table 1; Si

1.07 mg/L). In addition, particularly at Lake CF8 where glacial scour of the catchment was

minimal due to the cold-based nature of the LIS through the last few glaciations (Briner et al.

2005), the impact of the influx of catchment-derived materials may be minimal. Furthermore, the

limited catchment-lake interactions of Arctic lakes that are ice covered for much of the year limits

the effect of the catchment on pH (Wolfe 2002; Michelutti et al. 2007). For example, the basal

organic sedimentation of the Holocene at Lake CF3 was not alkaliphilous in nature, as would be

expected if catchment inputs dominantly controlled pH, but rather contained acidic diatom

species (Michelutti et al. 2007). The primary driver of pH in non-carbonate Arctic lakes is

54

therefore likely the effect of climatic trends on lake ice and within-lake DIC speciation dynamics

(Michelutti et al. 2007; Wolfe 2002). Prolonged ice cover traps expired CO2 (Psenner and

Schmidt 1992; Wolfe 2002) and reduces primary production (Douglas and Smol 1999), lowering

the pH of lakes during cold periods, while during warm periods, CO2 is exchanged with the

atmosphere and also consumed through phytoplankton photosynthesis, thereby increasing pH

(Psenner and Schmidt 1992; Wolfe 2002).

These observations led Michelutti et al. (2007) to propose a model of climate-driven lake

ontogeny for Arctic lakes. During cold periods with prolonged ice cover, pH should be lower, or

more acidic, with attendant changes in the diatom communities. As climate warms and ice cover

becomes less pervasive, pH should become more alkaline (Michelutti et al. 2007; Psenner and

Schmidt 1992; Wolfe 2002). The early Holocene, the warmest of the epoch, exhibits this trend at

Lake CF8 (Figure 3) as well as at nearby Lake CF3 (Michelutti et al. 2007). The pH declined in

many Baffin Island lakes throughout the Holocene (Michelutti et al. 2007; Miller et al. 1999;

Wolfe 1996; Wolfe and Hartling 1996; Wolfe et al. 2000), including Lake CF8. Lakes elsewhere

in the Arctic that lie on poorly buffered terrain have also captured declines in pH, particularly

through the Neoglacial period with increased ice cover (e.g. Michelutti et al. 2006). Lake CF8

showed the same trend through the LIG as well, which has also been demonstrated in the

Robinson Lake diatom record (Miller et al. 1999) and the Fog Lake record (Wolfe et al. 2000).

Therefore, acidification as lakes develop may typify interglacial periods within this geological

setting. However, the pH of Lake CF8 is currently acidic, and has become more so through the

recent lake history (Figure 3), whereas as predicted by DIC speciation, nearby Lake CF3 has

increased in alkalinity within the past century (Briner et al. 2006; Michelutti et al. 2007).

The different response of Lake CF8 compared to Lake CF3 and other Baffin Island lakes

is likely not due to any geological difference, and most of these lakes have been shown to be

55

largely isolated from their catchments. Vegetation was broadly established across Baffin Island

at the same time and has remained relatively consistent (Kerwin et al. 2004), which therefore

does not explain the differing responses of these lakes. The most likely disparity between Lakes

CF3 and CF8 that has led to the modern acidic pH in Lake CF8 is the difference in altitude. As

previously described, Lake CF8 lies over 150 m asl higher than Lake CF3, and therefore almost

certainly experiences later ice-free and earlier ice-on dates. Fog Lake, farther south in latitude

but higher in altitude compared to Lake CF8, retains an ice pan currently in the summer months

(Wolfe et al. 2000). This longer ice cover may contribute largely to the still acidic pH of Lake

CF8, and while the pH of Fog Lake has elsewhere tracked climate well, the modern pH is still

acidic (Wolfe et al. 2000). Therefore, the same overall trends in pH are likely occurring at both

CF3 and CF8, with a muted response at Lake CF8 due to longer ice cover in the warm season.

Additionally, the early Holocene differences in the diatom response between these two lakes may

suggest that some catchment erosion occurred post-glacially at Lake CF8, which slowed the

Holocene acidification in relation to Lake CF3. The catchment size of Lake CF8 is twice that of

Lake CF3, and thus the potential exists for more erosional inwash at Lake CF8. The

reconstructed environment of Lake CF8 in the early Holocene (Zone 3) does not indicate the

pronounced early warmth that has been inferred at Lake CF3; therefore, the early alkalinity of

Lake CF8 is likely tied to catchment effects rather than less ice cover. Furthermore, the early

Holocene diatom assemblages at Robinson Lake, and thus inferred pH (Miller et al. 1999), are

similar to Lake CF8, and Wolfe and Härtling (1996) also suggest that several Cumberland

Peninsula lakes were initially more alkaline. The progressive acidification throughout each

interglacial, including the Holocene, could be impacted by both increasing ice cover towards the

end of each period, as well as the progressive stabilization of catchment sources of alkalinity.

Therefore, while invoking climate and ice cover to explain pH fluctuations broadly throughout

interglacial periods characterizes Arctic lakes well, the general trend of this relationship may be

56

altered due to differences in the specific characteristics and history of each lake and its catchment

(e.g. Wolfe 2002).

4.3 The Recent Lake CF8 Sediments

Current climate warming is undoubtedly affecting Arctic lakes. The past ~ 150 years

have experienced the highest temperatures of the past four centuries in the Arctic (Overpeck et al.

1997). The typical changes associated with a warmer climate include increased duration of the

open-water season and thus a decline in ice cover, increased thermal stratification, and attendant

effects on the biota of lakes. Furthermore changes in rainfall patterns may impact vegetation and

the weathering of surrounding catchments (e.g. Vincent 2009). In the past, the Baffin Bay region

was considered particularly affected by changes in average annual temperatures. Baffin Island

has been shown to have some of the lowest summer temperatures across the Arctic, except for

over the Greenland Ice Sheet, and summer temperatures correlate strongly to the position of the

mid-tropospheric trough over Baffin Island, which affects the source direction of prevailing

winds and thus the temperature of air masses over Baffin Island (Williams and Bradley 1985).

However, Baffin Island falls within the region that has shown some of the smallest increases in

surface air temperatures annually and seasonally from 1966 to 1995 (Serreze et al. 2000), as well

as from 1980 to 1999 and in projections into the future decades (Serreze and Francis 2006),

though Comiso (2003) clearly indicates some warming in this region.

A late-Holocene and Anthropocene chironomid-inferred temperature record from Lake

CF8 indicates that within the past ~ 50 years, unprecedented increases in both summer water

temperature and primary productivity have occurred (Thomas et al. 2008). The diatom response

within that time period, the top 2 cm of Zone 1 (Figure 3), recorded the persistence of the only

planktonic taxon present in any appreciable abundance throughout the cores, A. distans, as well as

57

a slight increase in both A. alpigena and A. perglabra. Benthic taxa also remained present in low

abundances, including Encyonema species, F. saxonica, N. affine, and P. biceps. The only

species to show a significant change in abundance is E. exigua, which increased to approximately

20% relative abundance within the past ~ 50 years. The diatom community diversity, while not

directly comparable to the other cores, did not fluctuate markedly in the surface sediments (N2

values in Zone 1, Figure 3). The relationship between a warming climate, leading to less ice-

cover in the warm months and therefore increasing habitat availability for a wider range of

diatom growth strategies, has been found in lakes from the high Arctic (e.g. Smol 1988; Smol et

al. 2005) to the Subarctic (e.g. Rühland and Smol 2005) to high altitude sites (e.g. Lotter and

Bigler 2000). The well-documented response of diatoms to recent climatic warming across the

low- to mid-Arctic is a distinct and significant increase in the abundance of planktonic species,

particularly Cyclotella taxa, often within the past 150 years, related to both decreased ice cover

and/or increasing thermal stratification which supports the vertical position of planktonic taxa

(e.g. Rühland et al. 2008; Smol et al. 2005). This trend has occurred locally at Lake CF11, also

on the Clyde Foreland (Smol et al. 2005). Lakes that retain ice cover for longer periods in the

warm months, however, may exhibit a muted response to recent warming in the diatom

community (Smol and Douglas 2007). The signal of warming in high-Arctic lakes and ponds is

often increased benthic diatom diversity, as a more complex habitat structure can develop in the

littoral zone with even a slightly longer ice-free season (Douglas et al. 1994; Douglas and Smol

1999; Michelutti et al. 2003; Michelutti et al. 2006). The length of the ice-free season may be

correlated with the elevation of lakes in the Clyde Foreland. Lake CF11, which lies at 96 m asl,

has shown a discernible increase in planktonic taxa, particularly Cyclotella, while the recent

diatom assemblages of Lake CF10 at 435 m have indicated increases in the relative abundance of

some benthic taxa (Wolfe 2006). Lake CF8 lies at an intermediate elevation, 195 m asl, and

exhibits recent diatom assemblages with more similarities to Lake CF10. Figure 5 shows the

58

elevation of Clyde Foreland and the location of each of these lakes; Lake CF10 lies in an alpine

col, above the regional elevation shown in Figure 5. A higher elevation may plausibly extend the

temporal length of ice-cover at Lake CF8 in relation to lower elevation sites on Clyde Foreland;

for example, Fog Lake, also at a high elevation, has retained an ice-pan for a portion of the

summer during cold periods, and often experiences only one month of ice-free conditions (Wolfe

et al. 2000). The timing of ice- breakup varies with ambient temperature at a range of latitudes

(e.g. Weyhenmeyer et al. 2004), and is known to have a significant impact on the ecological

processes within lakes (e.g. Lotter and Bigler 2000; Smol et al. 2005). Therefore, while the

temperatures on the eastern coast of Baffin Island are not presently rising as much as other Arctic

regions (e.g. Serreze et al. 2000; Serreze and Francis 2006), the muted but apparent biological

response at Lake CF8 indicates that the length of the ice-free season is increasing.

The muted response to current warming at Lake CF8 may be indicative of prolonged ice

cover due to high altitude, as discussed previously in the context of the apparent differing pH

responses of Clyde Foreland lakes. However, the CF8 record, as shown in Figure 3, has

experienced significantly large shifts in diatom species composition throughout the last ~ 200 ka.

Therefore, this lake can be expected to be sensitive to and respond to the modern warming of the

Anthropocene. An increase in benthic taxa has occurred at Lake CF8 (Figure 3), similar to many

high-Arctic systems, and the lack of Cyclotella species may be due to the absence of thermal

stratification in this lake. For example, the recent diatom assemblages of several thermally

stratified lakes in the Finnish Lapland were compared to lakes in the same region that remain

unstratified (Sorvari et al. 2002). The isothermal lakes did not exhibit a recent increase in

planktonic species, but rather a shift in the abundance of benthic species, while only the stratified

lakes experienced increases in planktonic taxa (Sorvari et al. 2002), as Cyclotella species require

stratification to maintain position in the photic zone of the water column (e.g. Ampel et al. 2008).

Furthermore, similar to the Lake CF8 record, an increase in the diversity of the diatom

59

community was not recorded in the Finnish isothermal lakes (Sorvari et al. 2002). Therefore, the

combination of retained ice cover in the present warm seasons, as well as a lack of thermal

stratification, may contribute to the muted but observed diatom response to anthropogenic

impacts in the upper sediments of Lake CF8. The shifts in diatom species that do occur can be

linked to the feedbacks between climate warming, ice cover, pH and expanding habitat

availability. As previously discussed, ice cover likely remains extensive at this lake, which, in

combination with a granitic catchment, has resulted in an acidic pH. The diatom species that has

apparently flourished in the modern lake environment, E. exigua, is an acidic epiphytic species,

and thus indicates not only the slightly acidic pH of the lake but also an expanding littoral habitat

zone, likely with mosses present as substrate for this diatom species. The parallel high abundance

of the epiphyte P. marginulatum also indicates a seasonally open littoral zone. As discussed by

Douglas and Smol (1999), even a small increase in the growing season length of Arctic lakes

allows for diversified habitat availability. A longer growing season also allows the development

of more complex growth strategies, such as epiphytic taxa (Douglas and Smol 1999). In addition,

benthic species may respond more directly to temperature increases compared to planktonics

(Anderson 2000).

The chlorophyll a concentrations of the uppermost sediments were anticipated to be

significantly higher in relation to the rest of the chlorophyll a signature, similar to other lakes in

the region (Michelutti et al. 2005). However, as shown in Figure 4, in the context of the past ~

200 ka, the modern chlorophyll a concentrations, and thus inferred lacustrine production, is not

remarkable. Production appears to have peaked multiple times during the Holocene, indicated by

a larger positive deviation from the mean, while the surface core chlorophyll a indicates similar

values to several periods of the Holocene. An additional complementary proxy indicator of

organic content, % carbon, also shows little discernable increase in the surface sediments

60

(unpublished data), also indicative of the strong influence of prolonged ice cover at Lake CF8 that

persists even with regional warming.

The Arctic is regarded as an early indicator of global temperature changes of the

Anthropocene. While the diatom biota of many Arctic lakes have already responded as distinct

assemblage shifts towards open-water planktonic species, some lakes, including both high Arctic

and some higher-altitude Baffin Island lakes, have only recently begun to indicate discernable

changes in the diatom community, marked by increasing benthic taxa (e.g. Michelutti et al. 2003;

Michelutti et al. 2006; Wolfe et al. 2006a; this study). Furthermore, the extremely low

sedimentation rates in the Arctic translate to the requirement of multiple consecutive years of

directional diatom shifts for a signal to be recorded in the sediments (Michelutti et al. 2003). The

recent changes in the diatom benthos of Lake CF8 are undoubtedly distinct in the context of the

entire record, though presently show a muted response, most likely due to lake ice cover.

4.4 Summary and General Conclusions

Due to the cold-based, non-erosive glaciation of regions of eastern Baffin Island, the

Lake CF8 basin has recorded and retained organic sedimentation throughout multiple interglacial

periods, and represents the longest temporal lacustrine record so far examined from within the

limits of the LIS. Therefore, the Lake CF8 sediment record has provided a unique opportunity to

examine limnological and climatic shifts throughout multiple interglacial periods using diatoms

as the primary biological indicator, allowing comparisons between interglacials as well as the

contextualization of the current limnological regime in relation to past warm periods. This

research has shown that similar lake ontogenetic trends occurred throughout each warm period,

indicated by comparable diatom assemblages and shifts between interglacials, mediated by the

influence of climate on the physical and chemical conditions of the lake. Furthermore, this

61

region, with little glacial erosion and thus scarcity of glacial till, as well as sparse tundra

vegetation, provides the opportunity to examine the ontogeny of a lake with a limited catchment

effect. The strikingly similar changes throughout each interglacial suggest that climate drives

diatom communities indirectly through physical and chemical changes in this lake environment.

In addition, the recent changes in the diatom record show that the benthic, littoral habitat

is likely increasing in complexity, similar to other high Arctic or ice-dominated lakes. The

uppermost sediment units record an expansion of the acidophilous epiphyte Eunotia exigua and

other Eunotia species. However, this is a muted response when compared to lower altitude lakes

in Clyde Foreland, and prolonged ice cover has been suggested as a driving influence on the

present limnological environment. The recent shifts in diatom assemblages that have occurred,

however, indicate a distinct response in relation to the ~ 200 ka record. A prolonged present

interglacial period due to anthropogenic greenhouse gas emissions has been suggested by Berger

and Loutre (2002), and may be indicated by the unique present diatom assemblages at Lake CF8,

which are unlike those of the later portions of the past two interglacials.

62

4.5 Figures

4.5.1 Captions

Figure 5. An elevation map of the Clyde Foreland, Baffin Island, Nunavut, Canada. Lakes CF8 (70°33’ N, 68°57’ W), CF10 (70°26’ N, 69°07’ W and CF11 (70°28’ N, 68°40’ W) are shown. Elevation is indicated in the figure legend, differentiated by shade. From: A.P. Wolfe.

Figure 5.

63

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Appendices

Appendix A. The names used for the dominant diatom species (>5% relative abundance) in the Lake CF8 sediment record, with corresponding synonyms and taxonomic authorities.

Taxon Synonym Authority Achnanthes acares Hohn & Hellerman Achnanthes curtissima Carter Achnanthes lacus-vulcani Lange-Bertalot & Krammer Achnanthidium kriegeri Achnanthes kriegeri Krasske Achnanthidium minutissimum Achnanthes minutissima (Kützing) Czarnecki Aulacoseira alpigena (Grunow) Krammer Aulacoseira distans (Ehrenberg) Simonsen Aulacoseira lirata (Ehrenberg) Ross Aulacoseira perglabra (Østrup) Haworth Aulacoseira valida (Grunow) Krammer Brachysira brebissonii Ross in Hartley Caloneis aerophila Bock

Cavinula pseudoscutiformes Navicula pseudoscutiformes (Hustedt) Mann & Stickle in Round

Cavinula variostriata Navicula variostriata (Krasske) Mann & Stickle in Round, Crawford & Mann

Diadesmis laevissima (Cleve) Mann in Round Encyonema gaeumannii Cymbella gaeumannii (Meister) Krammer Encyonema hebridicum Cymbella hebridica (Gregory) Grunow ex Cleve Eunotia bilunaris (Ehrenberg) Mills

Eunotia exigua (Brébisson ex Kützing) Rabenhorst

Eunotia paludosa Grunow Eunotia praerupta Ehrenberg Eunotia rhomboidea Hustedt Fragilaria pinnata/construens v. venter complex Staurosirella pinnata

(Ehrenberg) Grunow in Van Heurck

Fragilariforma virescens Fragilaria virescens v. exigua (Grunow) Krammer & Lange-Bertalot

Frustulia rhomboides (Ehrenberg) De Toni Frustulia saxonica Frustulia rhomboides v. saxonica (Rabenhorst) De Toni Kobayasia subtilissima Navicula subtilissima (Cleve) Lange-Bertalot Navicula digitulus Hustedt Neidium affine (Ehrenberg) Pfitzer Neidium ampliatum (Ehrenberg) Krammer Nitzschia perminuta (Grunow) Peragallo Pinnularia biceps Gregory

Psammothidium bioretti Achnanthes bioretti (Germain) Bukhtiyarova & Round

Psammothidium helveticum Achnanthes helvetica (Hustedt) Bukhtiyarova & Round Psammothidium marginulatum Achnanthes marginulata (Grunow) Bukhtiyarova & Round

Pseudostaurosira brevistriata Fragilaria brevistriata (Grunow in Van Heurck) Williams & Round

Stauroneis anceps Ehrenberg

Appendix B. Raw diatom counts for the surface core from Lake CF8.

Interval (cm) 0.125 0.375 0.625 0.875 1.125 1.375 1.625 1.875 Achnanthes curtissima 0 1 0 0 0 7 0 0 Achnanthes daonensis 0 0 0 6 0 0 0 0 Achnanthes holstii 0 0 3 0 0 1 2 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 1 0 0 0 1 2 Aulacoseira alpigena 12 25 9 6 4 6 10 0 Aulacoseira distans group 146 158 151 176 163 165 161 181 Aulacoseira lirata 0 0 0 5 0 2 0 0 Aulacoseira perglabra 17 25 27 26 15 16 9 9 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 1 2 1 1 0 3 1 1 Brachysira microcephala 0 0 2 0 1 0 0 7 Caloneis aerophila 10 4 14 4 2 3 2 9 Chamaepinnularia mediocris 0 0 0 0 0 0 0 1 Encyonema gaeumannii 9 6 11 5 6 15 6 5 Encyonema hebridicum 12 5 7 9 12 18 6 13 Eunotia bilunaris 0 0 0 1 0 1 1 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 70 52 68 80 49 41 57 48 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia glacialis 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 1 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 1 0 0 0 0 1 0 0 Eunotia triodon 0 1 0 0 0 0 0 0 Fragilariforma virescens 4 6 11 6 5 7 9 6 Frustulia rhomboides 1 0 5 0 1 5 5 1 Frustulia saxonica 20 18 14 14 15 15 9 15 Kobayasia subtilissima 10 4 15 10 3 10 12 4 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 8 3 6 9 6 8 6 14 Neidium ampliatum 6 5 6 6 9 5 10 8 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium septentrionale 1 0 0 1 0 0 0 0 Nitzschia perminuta 0 1 1 0 0 1 1 0 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 8 3 5 5 6 2 2 6 Pinnularia rupestris 4 4 1 2 2 8 2 4 Psammothidim helveticum 7 7 14 7 3 12 5 9 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 93 76 66 77 46 77 102 84 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 1 1 0 0 0 0 0 Tabellaria flocculosa 1 0 1 0 0 0 3 1 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 441 407 441 456 348 429 422 428

Interval (cm) 2.125 2.375 2.625 2.875 3.125 3.375 3.625 3.875 Achnanthes curtissima 0 0 0 3 0 0 1 0 Achnanthes daonensis 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 1 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 2 0 2 0 0 9 0 2 Aulacoseira distans group 182 256 187 183 185 219 208 212 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 6 11 17 4 2 7 7 6 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 5 5 1 1 2 4 3 7 Brachysira microcephala 2 0 0 0 2 2 1 1 Caloneis aerophila 9 9 4 8 8 4 6 3

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Chamaepinnularia mediocris 0 0 0 0 0 0 1 0 Encyonema gaeumannii 13 18 21 15 9 23 13 8 Encyonema hebridicum 17 25 19 13 17 22 10 20 Eunotia bilunaris 0 1 0 1 0 2 3 1 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 30 35 26 22 17 16 24 17 Eunotia faba 0 1 0 0 0 0 0 0 Eunotia glacialis 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 4 1 0 1 0 1 2 1 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 1 5 1 2 2 0 2 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 18 15 14 14 20 11 5 16 Frustulia rhomboides 5 3 0 0 1 1 0 0 Frustulia saxonica 20 24 23 21 26 12 23 16 Kobayasia subtilissima 11 11 14 9 6 13 5 12 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 18 16 12 11 7 5 12 13 Neidium ampliatum 12 8 3 11 5 1 8 6 Neidium bisulcatum 0 0 0 2 3 2 0 5 Neidium septentrionale 0 0 0 0 0 0 0 0 Nitzschia perminuta 1 0 0 0 0 1 1 0 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 9 12 6 10 10 10 7 12 Pinnularia rupestris 5 9 3 1 4 1 5 1 Psammothidim helveticum 13 7 4 7 9 11 10 14 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 90 82 99 91 84 69 100 84 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 1 1 0 0 0 Surirella linearis 0 1 0 0 2 0 0 0 Tabellaria flocculosa 0 2 0 0 0 0 0 0 Tabellaria quadreseptata 0 0 1 1 1 0 0 1 TOTAL VALVES 473 557 458 432 423 446 457 458

Interval (cm) 4.125 4.375 4.625 4.875 5.125 5.375 5.625 5.875 Achnanthes curtissima 2 0 0 0 0 0 0 0 Achnanthes daonensis 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 1 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 2 Aulacoseira alpigena 0 0 4 0 2 0 1 4 Aulacoseira distans group 180 181 210 185 168 230 199 221 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 6 7 5 2 6 2 9 7 Brachysira arctoborealis 0 0 0 0 0 0 2 0 Brachysira brebissonii 3 4 5 6 6 1 1 3 Brachysira microcephala 0 1 3 1 1 0 0 0 Caloneis aerophila 5 8 3 4 8 0 5 0 Chamaepinnularia mediocris 0 0 0 2 0 1 0 0 Encyonema gaeumannii 21 16 13 21 16 19 14 21 Encyonema hebridicum 16 19 23 13 23 10 12 22 Eunotia bilunaris 0 4 1 2 1 0 0 0 Eunotia denticulata 0 0 1 0 0 0 1 0 Eunotia exigua group 21 15 17 21 20 14 12 9 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia glacialis 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 1 0 0 1 2 2 1 2 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 1 1 0 3 1 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 11 12 11 13 13 18 22 16 Frustulia rhomboides 2 0 2 0 0 0 0 0

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Frustulia saxonica 19 26 24 26 18 22 15 14 Kobayasia subtilissima 5 10 8 8 11 7 10 2 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 9 12 14 16 19 9 15 15 Neidium ampliatum 6 5 5 5 9 9 9 8 Neidium bisulcatum 0 1 3 0 1 2 1 1 Neidium septentrionale 0 0 0 0 0 0 0 0 Nitzschia perminuta 0 0 0 2 0 0 0 0 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 9 12 21 11 13 5 6 6 Pinnularia rupestris 4 0 1 1 2 1 3 6 Psammothidim helveticum 3 7 3 11 13 8 8 5 Psammothidium bioretti 0 0 0 0 0 1 0 0 Psammothidium marginulatum 85 115 90 81 92 93 82 104 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 1 0 0 0 1 1 0 Tabellaria flocculosa 1 0 0 0 0 3 1 1 Tabellaria quadreseptata 0 0 0 0 0 0 1 0 TOTAL VALVES 409 457 467 433 445 458 434 470

Interval (cm) 6.125 6.375 6.625 6.875 7.125 7.375 8.125 8.625 Achnanthes curtissima 0 0 2 3 0 0 4 0 Achnanthes daonensis 0 0 0 0 0 1 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 1 2 4 2 4 3 3 4 Aulacoseira distans group 190 205 186 194 229 175 115 180 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 8 4 3 8 2 4 9 5 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 3 1 6 4 4 1 4 2 Brachysira microcephala 0 2 5 0 1 1 0 0 Caloneis aerophila 4 2 3 2 1 2 0 2 Chamaepinnularia mediocris 0 1 0 0 1 0 0 1 Encyonema gaeumannii 15 13 12 9 17 12 12 13 Encyonema hebridicum 19 20 19 17 28 30 24 17 Eunotia bilunaris 4 2 0 2 0 3 2 2 Eunotia denticulata 0 1 0 0 1 0 0 2 Eunotia exigua group 12 20 18 6 21 15 15 11 Eunotia faba 1 0 0 0 0 0 0 1 Eunotia glacialis 0 0 0 0 0 0 0 0 Eunotia groenlandica 1 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 4 1 1 3 1 4 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 3 2 2 3 0 0 1 1 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 17 14 18 26 16 33 20 12 Frustulia rhomboides 0 0 0 0 0 0 2 0 Frustulia saxonica 25 19 27 22 21 19 9 8 Kobayasia subtilissima 12 6 11 7 9 10 5 4 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 12 11 6 6 10 9 7 7 Neidium ampliatum 4 5 8 8 10 5 10 7 Neidium bisulcatum 1 1 0 1 0 0 0 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Nitzschia perminuta 0 2 0 0 0 0 0 0 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 6 4 7 3 1 11 12 7 Pinnularia rupestris 1 4 4 1 0 5 2 1 Psammothidim helveticum 5 1 5 3 5 4 3 5 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 109 89 104 99 91 92 59 48 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0

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Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 1 0 0 0 0 0 0 Surirella linearis 2 0 0 0 0 0 0 0 Tabellaria flocculosa 1 2 1 0 0 1 0 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 460 435 452 429 473 440 318 340

Interval (cm) 9.125 9.625 10.125 10.625 11.125 11.625 12.125 12.625 Achnanthes curtissima 2 2 0 1 1 2 0 1 Achnanthes daonensis 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 1 0 0 0 0 Aulacoseira alpigena 4 5 2 4 1 3 16 8 Aulacoseira distans group 174 192 212 180 171 168 176 152 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 2 3 4 4 1 3 1 2 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 1 3 0 0 1 3 3 2 Brachysira microcephala 0 0 1 0 0 0 0 0 Caloneis aerophila 2 0 1 1 0 4 4 0 Chamaepinnularia mediocris 1 1 0 0 1 0 0 0 Encyonema gaeumannii 11 12 3 10 6 7 5 8 Encyonema hebridicum 16 16 33 19 25 10 37 19 Eunotia bilunaris 3 4 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 12 6 4 3 9 7 7 13 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia glacialis 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 1 1 0 0 Eunotia meisteri v. bidens 2 2 0 2 1 1 2 0 Eunotia muscicola v. muscicola 1 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 1 1 0 0 1 2 0 Eunotia triodon 0 0 1 0 0 0 0 0 Fragilariforma virescens 22 28 15 17 11 8 14 28 Frustulia rhomboides 0 1 0 0 0 0 0 0 Frustulia saxonica 10 7 20 9 14 11 9 15 Kobayasia subtilissima 6 3 3 9 3 6 4 14 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 7 4 3 5 5 4 5 4 Neidium ampliatum 5 5 7 5 5 5 11 3 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium septentrionale 0 2 1 0 1 1 0 0 Nitzschia perminuta 1 0 0 0 2 2 0 2 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 13 4 8 8 10 9 14 9 Pinnularia rupestris 2 0 1 2 0 1 0 0 Psammothidim helveticum 5 4 1 9 6 6 2 13 Psammothidium bioretti 1 0 0 0 0 0 0 0 Psammothidium marginulatum 65 49 40 32 67 58 42 46 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria flocculosa 0 1 0 0 1 0 0 0 Tabellaria quadreseptata 0 0 0 0 0 2 0 0 TOTAL VALVES 368 355 361 321 343 323 354 339

Interval (cm) 13.125 13.625 14.125 14.625 15.125 15.625 16.125 16.625 Achnanthes curtissima 0 0 2 0 0 0 0 0 Achnanthes daonensis 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0

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Aulacoseira alpigena 2 2 5 0 7 2 3 0 Aulacoseira distans group 177 141 160 167 156 173 176 161 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 0 1 0 0 0 1 1 1 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 1 3 4 0 1 0 1 1 Brachysira microcephala 0 0 0 0 0 0 0 0 Caloneis aerophila 3 0 0 1 0 0 0 0 Chamaepinnularia mediocris 1 1 0 1 1 1 0 1 Encyonema gaeumannii 4 4 6 9 16 13 7 9 Encyonema hebridicum 17 41 28 24 32 21 19 19 Eunotia bilunaris 0 2 1 0 2 2 0 0 Eunotia denticulata 0 0 0 2 1 2 1 1 Eunotia exigua group 7 7 4 4 7 3 8 6 Eunotia faba 0 0 0 0 0 0 1 1 Eunotia glacialis 1 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 2 3 2 1 1 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 1 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 2 1 0 1 1 3 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 39 37 37 28 37 36 38 41 Frustulia rhomboides 1 1 0 0 0 0 0 0 Frustulia saxonica 14 9 12 21 11 16 17 30 Kobayasia subtilissima 7 3 5 2 1 5 6 1 Microcostatus krasskei 0 0 0 0 0 0 0 0 Neidium affine 7 7 6 2 3 5 1 6 Neidium ampliatum 4 12 7 8 6 5 1 9 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium septentrionale 1 3 1 5 1 1 0 0 Nitzschia perminuta 1 1 0 0 0 0 1 0 Nitzschia suchlandtii 0 0 0 0 0 0 0 0 Pinnularia biceps 9 19 14 6 5 1 4 4 Pinnularia rupestris 0 0 0 0 0 0 0 0 Psammothidim helveticum 4 2 2 2 2 4 2 2 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 41 43 29 45 44 32 43 31 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira construens v. venter 1 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria flocculosa 1 0 0 0 0 0 1 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 345 342 327 329 334 324 333 327

Interval (cm) 17.125 17.625 18.125 18.625 19.125 19.625 Achnanthes curtissima 0 0 2 0 0 0 Achnanthes daonensis 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 Aulacoseira alpigena 3 0 0 8 0 0 Aulacoseira distans group 152 159 137 128 147 147 Aulacoseira lirata 0 0 0 0 0 0 Aulacoseira perglabra 0 2 3 2 1 0 Brachysira arctoborealis 0 0 0 0 0 0 Brachysira brebissonii 1 3 1 0 0 0 Brachysira microcephala 1 0 0 0 0 1 Caloneis aerophila 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 1 0 1 Encyonema gaeumannii 19 10 10 21 15 14 Encyonema hebridicum 19 22 8 24 25 10 Eunotia bilunaris 1 3 1 1 0 4 Eunotia denticulata 1 0 0 0 0 0 Eunotia exigua group 3 5 8 7 2 6 Eunotia faba 0 2 0 1 1 2

79

Eunotia glacialis 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 3 3 Eunotia rhomboidea 2 4 2 0 2 12 Eunotia triodon 0 0 0 0 0 0 Fragilariforma virescens 51 49 38 35 34 34 Frustulia rhomboides 0 0 1 2 0 1 Frustulia saxonica 16 14 27 16 22 25 Kobayasia subtilissima 2 3 7 5 3 7 Microcostatus krasskei 0 0 0 0 0 0 Neidium affine 6 5 8 7 5 3 Neidium ampliatum 7 2 3 7 5 2 Neidium bisulcatum 0 0 0 0 0 0 Neidium septentrionale 0 0 0 0 3 1 Nitzschia perminuta 0 0 0 0 0 0 Nitzschia suchlandtii 0 0 0 0 0 0 Pinnularia biceps 6 6 8 4 8 9 Pinnularia rupestris 0 0 0 0 0 0 Psammothidim helveticum 1 1 2 0 0 2 Psammothidium bioretti 0 0 0 0 0 0 Psammothidium marginulatum 27 35 42 29 39 43 Pseudostaurosira brevistriata 0 0 0 0 0 0 Stauroneis neohyalina 1 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 Tabellaria flocculosa 0 0 0 0 0 1 Tabellaria quadreseptata 0 0 0 0 0 0 TOTAL VALVES 319 325 308 298 315 328

80

81

Appendix C. Raw diatom counts for the Holocene core from Lake CF8. Interval (cm) 5.5 6.5 8.5 10.5 12.5 13.5 14.5 16.5 Achnanthes chlidanos 1 1 3 0 1 4 0 2 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 3 1 0 3 0 1 1 0 Achnanthidium kriegeri 0 0 0 0 0 0 1 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 2 4 7 14 7 14 18 17 Aulacoseira distans group 40 61 104 72 87 128 96 137 Aulacoseira perglabra 1 3 5 8 3 2 1 4 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 12 4 2 4 2 2 1 2 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 28 9 12 19 6 2 2 2 Caloneis aerophila 1 0 0 1 2 1 2 1 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 1 5 0 3 1 0 0 0 Encyonema gaeumannii 3 4 3 2 12 3 4 4 Encyonema hebridicum 0 6 5 11 6 8 6 7 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 28 17 20 9 5 6 2 3 Eunotia bilunaris v. mucophila 4 3 6 1 2 0 2 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 3 6 2 0 2 4 7 4 Eunotia faba 0 1 0 0 0 1 0 0 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 6 0 0 0 1 2 Eunotia monodontiforma 0 1 0 3 1 0 2 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 1 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 7 6 8 12 3 10 3 1 Eunotia tenella 1 1 1 1 1 1 0 1 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 3 13 8 8 3 6 5 21 Frustulia rhomboides 0 3 3 6 1 3 0 2 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 1 3 5 3 3 9 7 7 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 1 0 0 2 1 8 1 3 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 3 0 0 2 0 4 2 Neidum affine 2 2 2 2 5 4 6 12 Nitzschia perminuta 1 0 0 4 0 0 0 0 Peronia fibula 0 0 0 1 0 0 0 0 Pinnularia biceps 1 6 1 6 7 8 9 7 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 1 1 3 6 3 Psammothidium marginulatum 65 55 78 72 45 60 67 57 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 1 0 1 0 0 Tabellaria flocculosa 0 1 3 0 1 1 1 0 Tabellaria quadreseptata 0 1 0 0 0 1 0 0 TOTAL VALVES 209 220 284 269 210 291 255 302

82

Interval (cm) 17.5 18.5 20.5 21.5 22.5 24.5 25.5 26.5 Achnanthes chlidanos 0 0 0 1 1 2 0 0 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 4 1 2 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 15 12 11 4 2 2 1 10 Aulacoseira distans group 113 122 140 135 135 120 79 75 Aulacoseira perglabra 1 5 2 1 0 0 0 4 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 3 2 0 0 0 0 11 10 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 1 1 1 0 0 8 20 14 Caloneis aerophila 0 1 0 0 1 0 1 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 2 2 3 Encyonema gaeumannii 5 7 1 1 0 2 3 3 Encyonema hebridicum 4 8 8 9 8 4 1 7 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 2 2 0 0 1 5 12 12 Eunotia bilunaris v. mucophila 1 2 0 1 0 0 0 2 Eunotia denticulata 0 0 0 0 0 0 0 1 Eunotia exigua group 6 5 2 6 3 3 2 0 Eunotia faba 1 0 0 0 0 5 2 2 Eunotia fallax 0 0 0 1 0 0 1 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 0 0 1 0 1 1 3 1 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 1 4 0 1 1 7 12 19 Eunotia tenella 1 0 0 0 1 0 0 0 Eunotia triodon 0 0 0 0 0 0 1 0 Fragilariforma virescens 12 6 26 28 30 24 14 12 Frustulia rhomboides 1 0 6 2 4 5 10 8 Frustulia rhomboides v. crassinervia 1 0 0 0 0 0 0 0 Frustulia saxonica 7 7 1 1 0 4 2 3 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 6 3 5 3 5 1 0 4 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 2 3 3 2 3 2 1 2 Neidum affine 4 6 4 5 7 4 3 5 Nitzschia perminuta 0 1 1 0 0 2 0 0 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 10 21 15 17 24 15 4 3 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 2 3 1 0 0 1 1 2 Psammothidium marginulatum 69 44 24 13 30 29 24 46 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 4 3 0 2 3 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 1 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 1 0 0 Tabellaria flocculosa 0 0 0 0 0 0 4 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 272 267 254 235 260 249 216 251

83

Interval (cm) 28.5 29.5 30.5 32.5 33.5 34.5 36.5 37.5 Achnanthes chlidanos 2 2 2 0 0 1 0 0 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 1 0 3 6 2 0 0 1 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 4 3 9 12 5 9 3 4 Aulacoseira distans group 89 125 96 111 161 126 168 188 Aulacoseira perglabra 0 0 4 10 5 3 6 3 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 4 8 6 3 3 2 5 1 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 11 1 17 10 2 3 3 2 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 3 4 0 0 1 1 1 1 Encyonema gaeumannii 4 2 5 6 0 3 4 3 Encyonema hebridicum 2 4 3 3 2 5 2 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 8 6 9 7 0 3 0 3 Eunotia bilunaris v. mucophila 3 5 3 0 0 1 0 2 Eunotia denticulata 0 0 0 0 1 1 1 0 Eunotia exigua group 1 2 7 3 1 8 2 3 Eunotia faba 1 3 4 1 3 1 0 0 Eunotia fallax 0 0 1 4 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 1 Eunotia monodontiforma 0 2 0 4 1 3 1 0 Eunotia muscicola v. muscicola 0 1 0 0 0 0 0 0 Eunotia naegelii 1 0 0 0 0 0 0 0 Eunotia rhomboidea 16 12 22 23 4 0 4 10 Eunotia tenella 0 0 0 1 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 13 16 22 14 19 10 11 7 Frustulia rhomboides 3 8 9 9 2 5 4 1 Frustulia rhomboides v. crassinervia 0 0 0 0 1 2 0 2 Frustulia saxonica 4 4 5 4 7 6 5 3 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 0 1 1 3 6 5 7 1 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 1 1 3 2 2 6 1 2 Neidum affine 4 3 0 8 3 3 5 0 Nitzschia perminuta 1 1 1 0 0 0 1 0 Peronia fibula 1 0 1 0 0 0 0 0 Pinnularia biceps 9 5 5 13 22 21 17 8 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 4 4 5 2 0 Psammothidium bioretti 1 0 1 1 1 1 4 7 Psammothidium marginulatum 28 41 42 47 25 36 23 32 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 2 1 0 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 1 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 2 2 2 4 4 0 0 1 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 219 263 283 314 287 270 280 286

84

Interval (cm) 38.5 40.5 41.5 42.5 43.5 44.5 46.5 47.5 Achnanthes chlidanos 0 1 0 1 0 1 1 1 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 1 0 2 0 0 1 2 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 3 3 1 9 4 3 13 4 Aulacoseira distans group 152 128 138 131 165 174 179 151 Aulacoseira perglabra 9 4 19 9 10 19 16 9 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 4 6 5 1 2 1 2 5 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 1 2 2 2 3 1 3 3 Caloneis aerophila 1 1 0 2 0 0 2 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 3 1 0 0 1 0 Encyonema gaeumannii 1 6 2 1 4 5 4 1 Encyonema hebridicum 0 2 0 1 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 2 1 3 0 0 4 2 2 Eunotia bilunaris v. mucophila 1 0 2 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 2 0 2 2 4 1 1 2 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 2 0 3 0 0 0 2 3 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 0 0 1 2 0 3 1 2 Eunotia muscicola v. muscicola 0 0 0 0 1 0 0 7 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 5 15 13 11 6 7 13 17 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 3 4 11 13 13 13 21 42 Frustulia rhomboides 1 1 5 6 8 3 9 19 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 3 2 0 1 1 0 1 5 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 7 6 5 3 4 3 3 2 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 3 1 0 3 1 1 1 Neidum affine 1 3 1 0 0 0 0 0 Nitzschia perminuta 0 0 3 1 0 2 5 5 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 18 13 30 25 20 17 15 27 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 1 0 0 0 0 0 0 Psammothidium bioretti 5 2 2 6 4 1 0 3 Psammothidium marginulatum 36 34 25 19 24 26 33 18 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 2 0 1 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 0 1 0 0 1 1 1 2 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 258 239 279 247 279 287 332 331

85

Interval (cm) 48.5 49.5 50.5 52.5 53.5 54.5 55.5 56.5 Achnanthes chlidanos 0 0 0 1 0 0 0 0 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 1 0 0 1 0 0 1 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 2 10 6 10 6 0 6 3 Aulacoseira distans group 119 124 134 114 182 146 161 174 Aulacoseira perglabra 10 9 8 12 18 14 17 10 Brachysira arctoborealis 0 0 0 0 0 0 0 1 Brachysira brebissonii 3 2 4 5 5 1 3 0 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 10 9 6 2 6 3 2 2 Caloneis aerophila 0 0 0 0 0 1 0 2 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 1 0 0 0 0 1 0 1 Encyonema gaeumannii 3 3 2 1 1 4 6 6 Encyonema hebridicum 3 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 2 1 1 0 0 0 0 0 Eunotia bilunaris v. mucophila 1 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 2 4 1 1 1 2 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 4 0 0 3 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 0 0 1 1 2 0 0 0 Eunotia muscicola v. muscicola 10 6 9 4 4 2 2 4 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 20 14 14 13 3 8 7 5 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 40 53 43 78 25 22 13 23 Frustulia rhomboides 15 15 7 7 7 7 10 6 Frustulia rhomboides v. crassinervia 0 0 0 0 0 1 0 3 Frustulia saxonica 0 6 7 5 0 1 0 3 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 1 1 1 0 2 2 0 2 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 1 7 4 7 2 Neidum affine 1 1 0 0 0 0 0 0 Nitzschia perminuta 3 5 3 6 2 2 3 0 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 13 8 12 15 36 33 25 28 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 2 1 0 2 3 2 4 1 Psammothidium marginulatum 36 22 29 23 23 24 23 15 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 5 11 6 4 1 7 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 3 1 2 4 1 0 1 2 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 306 310 296 310 338 287 291 293

86

Interval (cm) 58.5 59.5 60.5 61.5 62.5 64.5 65.5 66.5 Achnanthes chlidanos 0 0 0 0 0 0 0 0 Achnanthes curtissima 0 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 5 1 0 3 2 5 3 1 Achnanthidium kriegeri 0 0 0 0 0 0 0 1 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 9 7 3 17 10 1 2 8 Aulacoseira distans group 195 190 168 182 176 160 145 134 Aulacoseira perglabra 14 13 14 10 15 4 12 5 Brachysira arctoborealis 0 0 1 1 2 0 1 1 Brachysira brebissonii 3 3 2 5 2 6 6 6 Brachysira intermedia 0 0 0 2 0 0 0 0 Brachysira microcephala 0 1 2 1 4 2 0 0 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 1 0 Encyonema gaeumannii 9 6 3 7 9 16 5 6 Encyonema hebridicum 0 0 1 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 1 0 0 0 3 0 0 1 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 1 1 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 2 0 0 Eunotia monodontiforma 0 0 0 2 1 0 1 1 Eunotia muscicola v. muscicola 0 2 1 4 4 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 5 9 2 2 3 0 0 3 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 29 24 23 32 23 52 51 59 Frustulia rhomboides 6 6 6 3 4 5 4 2 Frustulia rhomboides v. crassinervia 4 3 4 5 0 1 5 5 Frustulia saxonica 1 0 0 1 0 1 2 0 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 0 7 4 3 4 1 4 1 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 1 0 0 0 Neidum affine 0 0 0 0 0 1 0 0 Nitzschia perminuta 0 1 1 1 0 1 2 5 Peronia fibula 0 0 1 0 0 0 0 0 Pinnularia biceps 36 21 22 12 10 18 15 25 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 2 0 0 Psammothidium bioretti 0 0 0 1 1 1 4 0 Psammothidium marginulatum 22 17 13 26 15 19 12 16 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 1 0 0 0 Staurosira capucina 0 0 0 1 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 1 1 1 2 0 4 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 2 0 0 1 2 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 2 1 0 0 1 1 0 0 Tabellaria quadreseptata 0 1 0 0 0 0 0 0 TOTAL VALVES 341 313 275 323 292 302 277 284

87

Interval (cm) 67.5 68.5 70.5 71.5 72.5 73.5 74.5 75.7 Achnanthes chlidanos 0 1 4 0 3 0 0 2 Achnanthes curtissima 0 10 22 15 12 11 20 20 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 7 2 2 4 1 1 0 0 Achnanthidium kriegeri 0 2 0 5 6 1 2 5 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 4 4 2 0 0 0 2 0 Aulacoseira distans group 144 157 144 189 163 167 183 139 Aulacoseira perglabra 3 9 4 0 0 0 0 5 Brachysira arctoborealis 3 3 3 3 2 1 0 2 Brachysira brebissonii 6 5 9 10 10 9 9 3 Brachysira intermedia 1 0 0 0 0 1 0 0 Brachysira microcephala 1 1 4 0 0 0 0 1 Caloneis aerophila 0 0 1 0 0 0 1 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 2 0 0 0 0 0 0 0 Encyonema gaeumannii 3 2 10 10 13 10 14 16 Encyonema hebridicum 0 0 1 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 2 0 1 0 0 0 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 0 0 1 0 Eunotia faba 0 0 0 0 0 0 1 0 Eunotia fallax 0 2 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 2 1 1 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 3 9 8 5 5 0 3 0 Eunotia tenella 0 0 1 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 63 52 58 46 35 52 50 60 Frustulia rhomboides 1 0 0 0 1 0 0 0 Frustulia rhomboides v. crassinervia 4 2 1 0 0 0 0 0 Frustulia saxonica 0 2 0 0 2 0 0 0 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 3 3 2 3 4 2 3 1 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 1 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 1 0 0 0 0 0 Neidum affine 0 0 0 0 0 0 0 0 Nitzschia perminuta 2 4 7 4 4 6 1 2 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 11 27 20 22 25 23 28 21 Pinnularia neomajor 0 0 1 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 2 0 1 0 0 2 0 Psammothidium bioretti 0 1 0 0 1 1 2 1 Psammothidium marginulatum 13 29 17 20 16 15 11 12 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 1 2 1 1 0 2 0 Staurosira capucina 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 2 1 1 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 1 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 1 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 1 2 1 2 5 2 3 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 280 334 329 341 311 302 338 290

88

Interval (cm) 76.5 78.5 79.5 80.5 81.5 82.5 83.5 84.5 Achnanthes chlidanos 1 3 1 0 0 0 3 5 Achnanthes curtissima 21 17 15 21 17 14 26 20 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 0 0 20 13 20 7 4 8 Achnanthidium kriegeri 3 2 5 4 6 6 0 4 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 1 1 0 0 0 0 0 1 Aulacoseira distans group 152 85 6 7 0 6 0 16 Aulacoseira perglabra 0 4 1 0 0 0 0 2 Brachysira arctoborealis 2 2 0 0 0 0 0 0 Brachysira brebissonii 3 5 3 4 1 3 5 6 Brachysira intermedia 0 0 0 2 0 0 1 0 Brachysira microcephala 1 2 0 0 0 1 0 1 Caloneis aerophila 0 0 1 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 8 4 6 16 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Encyonema gaeumannii 25 18 5 9 5 8 11 10 Encyonema hebridicum 2 1 0 0 0 0 1 0 Encyonema minutum 0 1 0 0 0 0 0 0 Eunotia arcus 0 2 0 0 0 0 0 0 Eunotia bilunaris 1 0 0 1 0 0 1 3 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 1 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 0 0 0 0 2 1 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 0 1 0 1 0 3 0 3 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 1 0 0 1 1 Eunotia tenella 0 0 1 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 90 197 269 243 280 279 234 206 Frustulia rhomboides 0 0 0 1 0 0 0 0 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 0 1 1 0 0 0 0 0 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 8 1 1 1 0 2 2 1 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 0 0 0 0 0 Nitzschia perminuta 3 2 3 4 4 5 4 6 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 28 29 26 21 34 19 26 22 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 1 0 0 1 0 0 0 2 Psammothidium bioretti 1 2 0 2 1 0 1 0 Psammothidium marginulatum 16 21 9 11 14 15 17 14 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 3 0 1 0 3 3 Staurosira capucina 0 0 0 0 1 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 1 1 0 2 0 1 1 0 Staurosirella pinnata 0 2 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 2 8 4 8 4 7 7 9 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 362 408 374 358 396 380 356 360

89

Interval (cm) 86.5 87.5 88.5 89.5 90.5 91.5 92.5 94.5 Achnanthes chlidanos 3 2 2 3 3 2 4 6 Achnanthes curtissima 54 57 14 16 11 13 16 9 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthes lacus-vulcani 6 3 9 3 0 1 7 2 Achnanthidium kriegeri 3 3 7 3 7 9 4 4 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 0 0 0 0 0 3 0 Aulacoseira distans group 7 6 2 0 3 0 15 21 Aulacoseira perglabra 0 0 0 0 0 0 6 4 Brachysira arctoborealis 0 0 0 0 0 0 2 0 Brachysira brebissonii 1 0 0 0 0 0 0 0 Brachysira intermedia 2 1 0 0 0 0 0 1 Brachysira microcephala 1 0 1 0 4 0 3 3 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 28 18 39 52 19 1 4 2 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Encyonema gaeumannii 8 10 7 15 6 5 9 7 Encyonema hebridicum 0 0 2 1 0 0 1 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 4 1 1 0 1 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 1 0 2 0 1 3 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 2 3 2 1 3 5 0 2 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 0 1 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 272 205 279 280 258 242 224 220 Frustulia rhomboides 0 0 1 0 0 0 0 2 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 0 0 0 0 0 0 1 0 Gomphonema parvulum 0 0 0 0 1 0 0 0 Kobayasia subtilissima 6 1 3 2 4 3 2 2 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 1 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 1 0 Neidum affine 0 1 0 0 0 0 0 0 Nitzschia perminuta 5 8 5 1 8 5 4 5 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 22 24 22 34 27 41 21 17 Pinnularia neomajor 0 0 0 1 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 1 1 0 0 0 0 0 2 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 7 9 5 5 10 12 14 17 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 2 3 1 2 4 2 0 0 Staurosira capucina 0 0 0 0 2 3 1 6 Staurosira capucina v. rumpens 0 0 0 0 0 0 1 1 Staurosira construens v. venter 1 0 0 1 0 0 1 1 Staurosirella pinnata 0 0 0 0 0 0 0 1 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 2 1 1 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 3 7 9 6 6 13 7 20 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 434 362 411 430 381 360 353 360

90

Interval (cm) 95.5 96.5 97.5 98.5 100.5 102.5 103.5 104.5 Achnanthes chlidanos 4 4 2 2 0 0 0 2 Achnanthes curtissima 12 5 4 5 15 41 29 13 Achnanthes holstii 2 0 0 0 1 0 0 1 Achnanthes lacus-vulcani 6 0 4 2 3 1 3 3 Achnanthidium kriegeri 4 12 15 13 11 24 1 1 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 0 0 0 0 0 0 0 Aulacoseira distans group 0 4 0 12 29 2 0 9 Aulacoseira perglabra 0 1 0 1 5 0 0 2 Brachysira arctoborealis 0 0 0 0 1 0 0 0 Brachysira brebissonii 1 1 0 1 1 0 0 0 Brachysira intermedia 0 1 0 0 0 0 0 1 Brachysira microcephala 0 2 0 0 2 0 0 0 Caloneis aerophila 0 0 0 0 0 1 0 0 Cavinula pseudoscutiformes 0 0 0 0 1 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 1 0 0 0 Encyonema gaeumannii 8 11 18 16 23 2 0 0 Encyonema hebridicum 4 0 2 0 1 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 1 9 16 13 0 0 0 0 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 1 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 2 3 2 1 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 1 0 0 0 Eunotia monodontiforma 7 12 4 1 4 2 2 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 2 0 0 1 0 0 1 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 223 166 164 136 176 231 347 377 Frustulia rhomboides 0 0 0 0 4 0 0 0 Frustulia rhomboides v. crassinervia 0 0 0 0 1 0 0 0 Frustulia saxonica 0 0 0 1 2 0 0 0 Gomphonema parvulum 7 5 2 3 0 0 1 0 Kobayasia subtilissima 0 1 0 0 1 1 0 2 Navicula digitulus 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 1 0 0 3 1 3 3 2 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 1 0 0 0 0 0 0 Neidum affine 0 0 0 0 1 0 0 0 Nitzschia perminuta 7 5 9 8 6 17 4 7 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 16 13 15 16 16 21 9 8 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 2 2 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 1 1 0 0 0 0 0 Psammothidium marginulatum 24 31 31 50 52 34 39 28 Rossothidium pusilla 0 0 0 0 0 0 0 0 Stauroneis neohyalina 1 3 0 1 1 1 2 0 Staurosira capucina 4 2 9 1 6 9 0 1 Staurosira capucina v. rumpens 1 1 2 0 1 0 1 0 Staurosira construens v. venter 0 2 1 3 1 5 0 0 Staurosirella pinnata 1 1 0 0 1 3 1 3 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 16 16 28 27 13 25 11 9 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 352 317 331 317 383 423 453 470

91

Interval (cm) 106.5 107.5 108.5 110.5 111.5 112.5 113.5 114.5 Achnanthes chlidanos 1 2 1 0 2 1 0 0 Achnanthes curtissima 37 60 14 1 0 0 0 0 Achnanthes holstii 1 1 4 0 0 0 2 0 Achnanthes lacus-vulcani 0 0 2 1 0 0 0 0 Achnanthidium kriegeri 1 2 1 0 0 3 2 6 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 0 0 0 0 0 0 0 Aulacoseira distans group 6 0 5 1 0 3 0 5 Aulacoseira perglabra 0 0 0 0 0 0 0 0 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 0 0 0 1 0 0 0 0 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 0 1 1 0 1 0 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 1 1 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Encyonema gaeumannii 0 0 1 0 0 0 0 0 Encyonema hebridicum 0 0 1 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 0 Eunotia bilunaris v. mucophila 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 1 0 0 0 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 0 1 0 1 0 1 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia monodontiforma 1 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia rhomboidea 2 0 0 1 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma virescens 225 239 243 177 79 51 181 290 Frustulia rhomboides 0 1 1 1 0 0 0 0 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 0 0 0 0 0 0 0 0 Gomphonema parvulum 0 0 0 0 0 0 0 0 Kobayasia subtilissima 1 0 0 0 1 0 0 0 Navicula digitulus 0 0 0 0 0 0 1 1 Navicula gallica v. perpusilla 2 2 0 0 0 0 0 0 Navicula veneta 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 0 0 1 0 0 Nitzschia perminuta 4 5 2 6 4 0 8 6 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 23 34 22 29 40 32 26 0 Pinnularia neomajor 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 4 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 0 1 0 0 0 0 0 Psammothidium marginulatum 27 28 38 24 16 22 9 7 Rossothidium pusilla 0 0 0 1 0 2 0 0 Stauroneis neohyalina 0 2 0 0 1 1 2 2 Staurosira capucina 1 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 3 1 1 0 0 0 Staurosira construens v. venter 0 0 12 162 244 287 160 120 Staurosirella pinnata 2 10 18 23 25 20 30 18 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 7 7 8 7 12 8 6 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 342 393 377 438 426 432 429 461

92

Interval (cm) 115.5 116.5 117.5 118.5 120.5 Achnanthes chlidanos 0 0 0 1 0 Achnanthes curtissima 0 0 0 0 0 Achnanthes holstii 2 1 1 0 1 Achnanthes lacus-vulcani 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 Achnanthidium minutissimum 10 21 45 27 52 Aulacoseira alpigena 0 0 0 0 0 Aulacoseira distans group 0 1 0 1 0 Aulacoseira perglabra 0 0 0 0 0 Brachysira arctoborealis 0 0 0 0 0 Brachysira brebissonii 0 0 0 0 0 Brachysira intermedia 0 0 0 0 0 Brachysira microcephala 0 0 1 0 0 Caloneis aerophila 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 Cavinula variostriata 16 19 21 31 15 Chamaepinnularia mediocris 0 0 0 0 0 Encyonema gaeumannii 0 0 0 0 0 Encyonema hebridicum 0 2 0 0 0 Encyonema minutum 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 Eunotia bilunaris v. mucophila 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 Eunotia exigua group 0 0 0 0 0 Eunotia faba 0 0 0 0 0 Eunotia fallax 1 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 Eunotia monodontiforma 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 Fragilariforma virescens 309 316 219 284 246 Frustulia rhomboides 0 0 0 0 0 Frustulia rhomboides v. crassinervia 0 0 0 0 0 Frustulia saxonica 0 0 0 0 0 Gomphonema parvulum 0 0 0 0 0 Kobayasia subtilissima 0 0 0 0 0 Navicula digitulus 16 19 21 31 15 Navicula gallica v. perpusilla 0 0 0 0 0 Navicula veneta 0 2 5 2 1 Neidium ampliatum 0 0 0 0 0 Neidum affine 0 0 0 0 0 Nitzschia perminuta 15 31 55 50 68 Peronia fibula 0 0 0 0 0 Pinnularia biceps 0 0 0 0 0 Pinnularia neomajor 0 0 0 0 0 Pinnularia septentrionalis 0 0 3 0 0 Pinnularia subcapitata 0 0 0 0 0 Psammothidium altaicum 0 0 0 0 0 Psammothidium bioretti 0 0 0 1 0 Psammothidium marginulatum 10 7 9 2 7 Rossothidium pusilla 0 0 0 2 2 Stauroneis neohyalina 6 4 3 2 3 Staurosira capucina 0 0 0 0 1 Staurosira capucina v. rumpens 0 0 0 0 1 Staurosira construens v. venter 4 0 0 0 2 Staurosirella pinnata 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 Surirella linearis 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 Tabellaria flocculosa 0 0 0 0 0 Tabellaria quadreseptata 0 0 0 0 0 TOTAL VALVES 389 423 383 434 414

93

Appendix D. Raw diatom counts for the interstadial core from Lake CF8. Interval (cm) 94 95 97 3 7 Achnanthes holstii 0 1 0 0 0 Achnanthidium minutissimum 0 0 1 0 0 Aulacoseira alpigena 4 9 2 0 15 Aulacoseira distans group 21 16 1 15 8 Aulacoseira lirata 0 0 0 0 2 Aulacoseira perglabra 9 18 1 10 13 Cymbopleura amphicephala 0 0 1 0 0 Encyonema hebridicum 0 1 0 0 1 Eunotia bilunaris 0 2 2 1 1 Eunotia exigua group 0 0 9 4 2 Eunotia fallax 2 1 2 1 0 Eunotia parallela v. parallela 0 1 2 1 0 Eunotia praerupta 1 0 0 1 0 Eunotia rhomboidea 1 0 0 1 0 Fragilariforma virescens 80 82 4 61 70 Frustulia rhomboides 2 2 1 1 2 Frustulia saxonica 1 0 0 1 0 Kobayasia subtilissima 1 1 0 1 2 Muelleria luculenta 0 0 0 0 4 Navicula schmassmannii 0 0 0 1 0 Neidium affine 0 0 1 0 0 Pinnularia biceps 0 0 1 0 2 Pinnularia borealis 1 0 0 0 0 Psammothidim helveticum 9 9 0 7 7 Psammothidium marginulatum 248 185 194 212 191 Rossothidium petersenii 0 0 0 1 0 Stauroneis anceps 1 11 52 4 2 Stauroneis neohyalina 6 2 9 4 3 Staurosirella pinnata 0 0 0 0 2 Tabellaria flocculosa 10 6 32 39 8 TOTAL VALVES 397 347 315 366 335

94

Appendix E. Raw diatom counts for the Last Interglacial from Lake CF8. Interval (cm) 10 11 12 13 14 15 16 17 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 0 0 0 0 0 1 1 1 Achnanthes daonensis 0 0 0 0 4 0 1 0 Achnanthes holstii 0 0 0 0 0 0 0 9 Achnanthidium kriegeri 0 0 0 0 4 4 1 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 1 0 3 2 4 3 1 Aulacoseira distans group 0 1 0 0 14 6 15 19 Aulacoseira lirata 0 0 0 0 0 0 0 0 Aulacoseira perglabra 0 0 0 0 3 4 3 7 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira arctoborealis 0 0 0 0 0 0 1 0 Brachysira brebissonii 0 0 1 0 0 1 2 1 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 0 0 0 0 1 2 Caloneis aerophila 0 0 0 0 0 0 2 2 Cavinula pseudoscutiformes 0 0 0 0 0 0 1 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 0 0 0 0 0 0 0 0 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 0 0 0 1 2 6 Diadesmis laevissima 0 0 0 0 2 0 0 1 Encyonema gaeumannii 0 0 0 0 0 0 0 1 Encyonema hebridicum 0 0 0 0 0 0 0 0 Encyonema lunatum 0 0 0 0 0 1 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 2 2 4 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 3 3 4 9 Eunotia faba 0 0 0 0 0 1 0 7 Eunotia fallax 0 0 0 0 0 0 1 0 Eunotia groenlandica 0 0 0 0 0 0 2 1 Eunotia incisa 0 0 0 0 0 0 0 0 Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 1 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 3 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 1 1 0 3 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 0 0 0 0 0 0 0 2 Eunotia tenella 0 0 0 0 0 0 1 0 Eunotia torula 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 1 1 1 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma exigua 0 2 2 2 6 0 0 1 Frustulia rhomboides 0 0 0 0 1 0 1 1 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 0 0 0 0 0 0 0 1 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 0 0 0 0 0 1 1 1 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 5 1 Navicula cryptocephala 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 1 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0

95

Neidium bisulcatum 0 0 0 0 0 0 1 0 Neidium dubium 0 0 0 0 0 0 0 0 Neidium hercynium 0 0 0 0 1 0 2 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 0 1 2 0 3 Nitzschia bryophila 0 0 0 0 0 0 0 0 Nitzschia perminuta 0 0 0 0 1 0 0 1 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 1 0 0 2 91 4 21 69 Pinnularia borealis 0 0 0 0 0 1 0 1 Pinnularia lapponica 0 0 0 0 0 3 18 6 Pinnularia rupestris 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Pinnularia viridis 0 0 0 0 0 0 0 0 Psammothidim helveticum 0 0 0 0 2 3 6 9 Psammothidium altaicum 0 0 0 0 2 0 0 0 Psammothidium bioretti 0 0 0 0 9 14 8 2 Psammothidium marginulatum 0 0 4 2 118 155 208 144 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 1 Stauroneis obtusa 0 0 0 0 0 0 1 1 Stauroneis phoenicenteron 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 2 0 0 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 1 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 2 2 0 0 Staurosirella pinnata 0 0 1 0 1 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 0 1 0 0 0 2 3 9 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 1 6 8 10 268 219 319 332

Interval (cm) 18 19 20 21 22 23 24 25 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 0 2 0 4 2 6 9 2 Achnanthes daonensis 0 0 0 5 2 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 1 1 1 0 0 1 1 1 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 3 2 0 5 30 26 30 55 Aulacoseira distans group 10 3 12 39 208 185 295 239 Aulacoseira lirata 0 0 4 0 0 5 5 3 Aulacoseira perglabra 2 3 4 8 42 43 49 53 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira arctoborealis 0 1 1 0 1 1 0 1 Brachysira brebissonii 5 0 1 2 4 0 2 2 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 0 0 0 0 0 0 Caloneis aerophila 1 3 1 2 0 0 1 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 1 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 1 1 0 0 1 0 0 0 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 1 6 0 0 0 0 0 Diadesmis laevissima 1 2 2 0 0 0 0 0

96

Encyonema gaeumannii 0 1 1 0 0 2 3 2 Encyonema hebridicum 0 0 1 3 0 0 0 4 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 1 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 2 3 3 3 0 1 2 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 5 4 4 1 1 0 1 0 Eunotia faba 0 0 2 0 0 0 0 0 Eunotia fallax 0 1 0 0 0 0 0 0 Eunotia groenlandica 6 0 2 2 1 0 1 0 Eunotia incisa 0 3 3 2 2 2 1 2 Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 1 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 1 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia praerupta v. bigibba 0 1 1 0 0 0 0 1 Eunotia rhomboidea 3 1 1 2 0 0 1 0 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 1 5 0 7 0 0 1 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 0 0 0 0 0 0 Eunotia triodon 1 1 3 2 2 1 0 0 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma exigua 1 2 0 3 1 1 4 5 Frustulia rhomboides 2 1 0 1 5 6 14 10 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 0 0 1 1 0 0 0 0 Gomphonema clevei 2 0 0 0 0 0 0 0 Kobayasia subtilissima 1 1 1 6 8 4 4 3 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 1 5 6 3 1 0 0 0 Navicula cryptocephala 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidium bisulcatum 1 0 0 0 3 2 0 0 Neidium dubium 0 0 0 0 2 1 4 4 Neidium hercynium 1 0 0 2 0 3 1 1 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 4 2 0 0 0 Nitzschia bryophila 0 0 0 0 0 0 0 0 Nitzschia perminuta 1 0 1 0 0 0 0 3 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 36 30 46 55 48 18 32 29 Pinnularia borealis 1 2 1 0 0 0 0 1 Pinnularia lapponica 9 4 4 6 3 0 4 1 Pinnularia rupestris 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Pinnularia viridis 0 0 1 0 0 3 3 0 Psammothidim helveticum 10 13 7 8 4 3 0 1 Psammothidium altaicum 0 0 0 0 1 0 1 0 Psammothidium bioretti 7 5 9 1 9 1 5 0 Psammothidium marginulatum 121 197 172 161 65 37 30 29 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 2 Stauroneis obtusa 0 1 0 4 0 1 0 0 Stauroneis phoenicenteron 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 0 0 0 1 0 Staurosira capucina v. 0 0 0 0 0 0 0 0

97

capitellata Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 2 1 0 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 1 1 0 4 Tabellaria fenestrata 1 1 0 0 0 0 1 0 Tabellaria flocculosa 4 8 1 4 2 2 4 1 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 241 312 305 347 451 356 510 460

Interval (cm) 26 27 28 29 30 31 32 33 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 1 3 5 2 1 2 0 1 Achnanthes daonensis 3 0 1 2 1 1 3 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 2 2 1 1 0 0 0 0 Achnanthidium minutissimum 0 0 0 0 2 0 0 4 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 2 36 56 3 19 13 11 42 Aulacoseira distans group 21 46 64 44 45 49 15 75 Aulacoseira lirata 4 13 57 51 9 4 3 4 Aulacoseira perglabra 13 61 73 26 7 8 4 37 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira arctoborealis 0 0 2 2 0 0 0 0 Brachysira brebissonii 2 2 2 6 0 0 5 5 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 1 2 0 1 0 0 0 1 Caloneis aerophila 3 0 1 2 1 2 1 0 Cavinula pseudoscutiformes 0 0 1 1 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 2 Cyclotella bodanica 1 2 1 0 0 0 0 0 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 1 0 0 0 1 6 0 4 Diadesmis laevissima 0 0 1 0 1 0 3 1 Encyonema gaeumannii 0 3 1 1 2 0 0 0 Encyonema hebridicum 0 0 2 0 4 3 0 12 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 4 0 0 3 3 10 2 12 Eunotia denticulata 0 0 0 0 0 1 0 0 Eunotia exigua group 1 0 1 2 2 12 0 6 Eunotia faba 0 0 0 2 0 0 0 0 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia groenlandica 3 0 1 0 1 1 1 1 Eunotia incisa 0 2 0 14 2 3 1 1 Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 2 2 0 0 0 2 2 1 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 1 0 0 0 1 0 1 2 Eunotia praerupta 2 0 1 0 1 0 1 1 Eunotia praerupta v. bigibba 0 0 1 0 0 1 1 0 Eunotia rhomboidea 0 0 0 0 1 1 0 2 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 1 0 1 0 5 1 1 8 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 1 0 0 0 0 0 Eunotia triodon 0 1 1 3 7 4 2 1

98

Fragilariforma constricta 0 0 1 0 0 0 0 0 Fragilariforma exigua 4 14 0 17 0 1 0 0 Frustulia rhomboides 3 9 3 16 1 2 5 3 Frustulia rhomboides v. crassinervia 0 0 1 0 1 0 0 0 Frustulia saxonica 0 0 2 1 1 0 0 3 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 0 0 0 1 1 4 2 9 Meridion circulare 0 0 1 0 0 0 0 0 Microcostatus krasskei 5 1 0 1 1 1 4 2 Navicula cryptocephala 0 3 4 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 2 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 0 0 0 0 0 1 0 3 Neidium hercynium 0 1 1 0 1 2 0 1 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 1 0 0 0 6 6 2 22 Nitzschia bryophila 0 0 2 0 0 0 0 0 Nitzschia perminuta 0 3 1 2 0 0 2 3 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 20 16 37 13 48 81 31 76 Pinnularia borealis 0 0 0 0 0 0 0 0 Pinnularia lapponica 14 4 0 3 5 12 15 13 Pinnularia rupestris 0 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Pinnularia viridis 2 1 0 1 0 0 1 1 Psammothidim helveticum 8 1 0 1 3 12 13 11 Psammothidium altaicum 3 0 0 0 0 0 0 0 Psammothidium bioretti 2 0 0 2 12 5 3 5 Psammothidium marginulatum 151 34 13 54 90 165 177 186 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 1 2 1 0 0 0 0 2 Stauroneis obtusa 0 0 1 0 0 0 1 0 Stauroneis phoenicenteron 0 0 2 1 1 1 0 0 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 0 1 0 0 2 0 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 3 1 0 1 2 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 5 0 0 0 1 Tabellaria fenestrata 0 0 0 0 0 0 1 0 Tabellaria flocculosa 2 3 6 0 0 2 6 6 Tabellaria quadreseptata 0 0 0 0 0 1 0 0 TOTAL VALVES 286 270 352 285 288 422 322 570

Interval (cm) 34 35 36 37 38 39 40 41 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 1 2 1 1 3 0 0 8 Achnanthes daonensis 1 0 0 0 0 0 0 0 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 1 0 0 0 0 Achnanthidium minutissimum 2 0 0 2 0 0 0 0 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 20 9 86 38 51 66 55 37 Aulacoseira distans group 45 12 107 87 160 196 213 267 Aulacoseira lirata 2 1 2 1 0 3 0 5 Aulacoseira perglabra 14 1 24 20 16 9 10 28

99

Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira arctoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonii 0 2 2 0 1 3 3 2 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 0 0 0 0 0 0 Caloneis aerophila 1 4 1 0 0 5 4 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 0 Cavinula variostriata 0 0 0 0 0 0 0 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 1 0 0 0 0 0 0 0 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 2 10 1 0 0 0 0 0 Diadesmis laevissima 0 0 1 0 0 0 0 0 Encyonema gaeumannii 3 2 0 0 2 5 2 3 Encyonema hebridicum 2 0 1 0 2 1 4 1 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 4 3 6 4 2 1 1 0 Eunotia denticulata 0 2 0 1 1 0 2 0 Eunotia exigua group 6 3 7 1 0 1 0 0 Eunotia faba 0 0 0 0 0 1 1 1 Eunotia fallax 0 0 0 0 0 0 0 1 Eunotia groenlandica 0 0 0 1 0 0 0 0 Eunotia incisa 2 0 0 1 0 1 1 0 Eunotia intermedia 0 0 0 0 1 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 2 1 2 2 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 2 1 2 0 1 1 1 0 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 5 20 1 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 0 0 0 0 0 0 Eunotia triodon 2 0 1 3 1 0 1 0 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma exigua 0 1 0 0 0 0 1 0 Frustulia rhomboides 2 1 2 1 0 0 7 5 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 4 0 1 1 0 4 0 4 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 5 1 12 11 12 10 9 9 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 8 0 1 0 1 0 0 Navicula cryptocephala 0 0 0 0 0 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 4 0 0 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 0 0 3 1 6 5 11 8 Neidium hercynium 1 1 6 1 0 0 0 0 Neidium septentrionale 0 0 0 0 2 5 3 0 Neidum affine 7 10 13 16 2 0 0 0 Nitzschia bryophila 0 0 0 0 0 0 0 0 Nitzschia perminuta 0 0 0 0 0 0 0 0 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 79 121 33 56 48 32 35 23 Pinnularia borealis 1 0 0 0 0 0 0 0 Pinnularia lapponica 4 5 2 2 2 0 0 0 Pinnularia rupestris 0 0 0 0 0 0 0 2 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 1 0 0 0 0

100

Pinnularia viridis 0 0 0 1 3 2 1 1 Psammothidim helveticum 8 7 4 13 12 8 7 5 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 1 0 0 0 0 3 0 0 Psammothidium marginulatum 116 129 73 88 61 27 34 22 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 0 1 0 0 0 Stauroneis obtusa 1 0 0 0 0 0 0 0 Stauroneis phoenicenteron 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 0 Staurosira capucina 1 0 0 0 0 0 0 0 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 5 2 0 1 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 1 0 3 0 0 2 Tabellaria fenestrata 1 0 0 1 0 0 0 0 Tabellaria flocculosa 2 2 1 7 6 1 1 0 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 350 359 396 369 401 395 408 434

Interval (cm) 42 43 44 45 46 47 48 49 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 4 1 0 3 4 3 1 5 Achnanthes daonensis 0 5 7 0 3 0 0 1 Achnanthes holstii 0 1 0 0 0 0 1 1 Achnanthidium kriegeri 0 0 0 0 0 1 0 0 Achnanthidium minutissimum 0 0 0 0 0 1 0 2 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 35 51 13 43 40 36 30 22 Aulacoseira distans group 244 244 257 274 252 225 249 225 Aulacoseira lirata 1 10 5 13 8 32 49 50 Aulacoseira perglabra 40 12 26 31 33 42 24 19 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira arctoborealis 1 0 0 0 0 4 7 0 Brachysira brebissonii 0 0 3 1 0 1 0 1 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 1 0 2 0 1 0 2 0 Caloneis aerophila 2 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 0 2 Cavinula variostriata 0 0 0 0 0 0 2 0 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 0 0 0 0 0 0 0 0 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 0 1 0 0 0 0 Diadesmis laevissima 0 1 0 0 0 0 0 0 Encyonema gaeumannii 11 3 4 8 5 5 3 4 Encyonema hebridicum 0 8 0 0 0 1 3 3 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 1 0 2 0 0 Eunotia exigua group 2 0 1 0 0 0 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia incisa 1 0 0 0 0 0 0 0

101

Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 2 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 2 0 0 0 Eunotia praerupta 0 0 0 0 0 0 0 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 2 1 1 0 0 0 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 0 0 0 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 0 0 0 0 0 0 Eunotia triodon 1 0 0 0 0 0 0 0 Fragilariforma constricta 0 0 0 0 1 0 0 0 Fragilariforma exigua 0 11 3 0 9 16 7 11 Frustulia rhomboides 11 4 6 7 9 8 8 15 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 2 10 3 3 3 5 4 3 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 7 2 14 2 6 5 4 1 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 0 0 Navicula cryptocephala 0 0 0 0 0 0 1 2 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 5 2 0 1 5 2 1 3 Neidium hercynium 1 2 2 0 2 0 0 1 Neidium septentrionale 0 0 2 2 0 0 0 1 Neidum affine 1 0 0 0 1 0 2 0 Nitzschia bryophila 0 0 0 0 0 0 0 0 Nitzschia perminuta 1 0 1 1 0 2 3 4 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 30 18 33 19 21 28 38 33 Pinnularia borealis 1 0 0 0 0 0 0 0 Pinnularia lapponica 0 0 1 0 0 0 0 0 Pinnularia rupestris 4 3 1 3 1 0 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Pinnularia viridis 2 1 0 3 3 2 1 2 Psammothidim helveticum 3 1 4 1 0 3 2 2 Psammothidium altaicum 0 2 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 17 11 16 18 17 7 8 2 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 2 1 0 0 1 0 5 3 Stauroneis obtusa 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 0 Staurosira capucina 0 0 1 0 0 0 0 0 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 1 0 0 0 0 0 0 1 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 1 0 0 1 2 0 0 Surirella linearis 0 1 1 0 0 0 3 0 Tabellaria fenestrata 0 0 0 0 1 0 0 0 Tabellaria flocculosa 3 3 2 0 3 3 1 5 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 434 409 410 436 433 438 459 424

102

Interval (cm) 50 51 52 53 54 55 56 57 Achnanthes acares 0 0 0 0 0 0 0 0 Achnanthes curtissima 7 8 9 15 9 14 6 10 Achnanthes daonensis 0 0 2 0 0 0 0 0 Achnanthes holstii 3 3 0 0 2 8 2 0 Achnanthidium kriegeri 1 0 2 0 0 1 0 0 Achnanthidium minutissimum 0 1 1 0 0 1 1 0 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 23 23 30 68 57 44 72 31 Aulacoseira distans group 211 203 210 158 100 85 39 66 Aulacoseira lirata 29 41 27 47 70 68 92 90 Aulacoseira perglabra 22 15 22 24 43 56 38 43 Aulacoseira valida 0 0 0 4 4 7 0 4 Brachysira arctoborealis 1 3 4 3 3 2 0 3 Brachysira brebissonii 4 2 2 1 1 4 3 2 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 1 1 1 0 1 2 2 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 3 2 2 1 0 2 1 4 Cavinula variostriata 0 1 0 2 3 0 5 2 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 1 1 Cyclotella bodanica 0 2 1 0 0 3 3 2 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 0 0 0 0 1 0 Diadesmis laevissima 0 0 0 0 0 1 0 0 Encyonema gaeumannii 9 4 5 4 4 3 4 2 Encyonema hebridicum 1 3 2 7 0 0 2 0 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 1 0 0 0 0 0 0 0 Eunotia denticulata 1 0 0 0 0 0 0 0 Eunotia exigua group 1 0 0 2 0 1 0 1 Eunotia faba 1 1 1 0 0 0 0 2 Eunotia fallax 0 0 0 0 0 0 2 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia incisa 0 0 0 0 0 0 0 0 Eunotia intermedia 1 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 1 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 1 0 0 1 0 0 Eunotia praerupta 0 0 0 2 0 0 0 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 1 0 1 0 0 0 0 Eunotia serra 1 0 0 1 0 0 1 0 Eunotia steineckii 0 0 0 0 0 0 1 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 0 1 0 0 0 1 Eunotia triodon 0 0 0 0 0 0 0 0 Fragilariforma constricta 0 0 0 0 0 1 0 0 Fragilariforma exigua 7 16 9 20 20 23 37 39 Frustulia rhomboides 12 9 10 6 4 4 9 7 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 3 0 Frustulia saxonica 3 8 7 8 3 7 6 4 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 4 5 2 0 0 1 1 2 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 0 0 Navicula cryptocephala 3 5 1 3 4 4 5 2 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 2 0 1 0 0 Neidium ampliatum 0 0 0 0 0 0 0 0

103

Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 0 0 0 0 0 0 0 0 Neidium hercynium 3 2 3 0 2 2 1 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 3 0 0 0 0 1 0 0 Nitzschia bryophila 0 0 0 0 0 3 1 1 Nitzschia perminuta 5 5 6 10 6 3 1 5 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 32 28 13 52 48 47 50 52 Pinnularia borealis 0 0 0 0 0 0 0 0 Pinnularia lapponica 0 0 2 0 0 0 0 2 Pinnularia rupestris 0 0 1 1 2 1 0 0 Pinnularia septentrionalis 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Pinnularia viridis 1 1 0 0 0 0 1 1 Psammothidim helveticum 0 2 0 0 0 0 0 1 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 10 2 4 0 6 7 4 1 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Sellaphora pupula 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 2 1 1 3 4 3 4 Stauroneis obtusa 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron 0 0 0 3 2 3 8 8 Stauroneis phoenicenteron v. brevis 0 0 0 0 0 0 0 6 Staurosira capucina 0 0 0 0 1 0 0 1 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 2 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 0 0 2 2 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 1 1 3 0 0 4 2 2 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 405 400 384 448 397 420 410 406

Interval (cm) 58 59 60 61 62 63 64 65 Achnanthes acares 0 16 4 1 2 4 1 5 Achnanthes curtissima 7 5 4 5 2 2 1 2 Achnanthes daonensis 0 0 1 1 0 1 0 0 Achnanthes holstii 1 0 2 3 1 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 0 0 0 Achnanthidium minutissimum 0 0 2 1 0 0 2 1 Amphora copulata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 18 27 17 29 19 13 11 11 Aulacoseira distans group 48 15 19 31 74 136 113 119 Aulacoseira lirata 115 147 182 151 152 71 83 65 Aulacoseira perglabra 23 4 10 8 13 18 27 14 Aulacoseira valida 11 4 2 2 11 6 14 12 Brachysira arctoborealis 0 1 2 1 3 1 1 2 Brachysira brebissonii 2 2 2 1 1 1 1 0 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 0 0 0 0 1 1 Caloneis aerophila 0 0 2 0 0 0 0 0 Cavinula pseudoscutiformes 5 2 4 1 2 6 2 1 Cavinula variostriata 1 2 4 3 1 3 0 1 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 4 11 11 12 4 3 2 7 Cyclotella pseudostelligera 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 1 1 0 2 6 1 Diadesmis laevissima 0 0 0 0 0 0 0 0

104

Encyonema gaeumannii 3 2 5 4 1 0 0 3 Encyonema hebridicum 0 1 2 2 0 2 1 1 Encyonema lunatum 0 0 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 1 3 Encyonopsis cesatii 0 0 0 0 0 0 1 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 0 Eunotia denticulata 1 0 1 0 0 1 0 0 Eunotia exigua group 3 0 0 0 0 0 1 1 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 1 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia incisa 0 0 0 0 0 0 0 0 Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 1 0 4 2 0 0 0 Eunotia praerupta 0 0 0 0 0 1 0 0 Eunotia praerupta v. bigibba 0 1 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 0 0 0 0 Eunotia serra 0 0 0 0 0 0 0 0 Eunotia steineckii 0 0 0 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 2 0 0 0 0 0 1 0 Eunotia triodon 0 3 0 0 0 0 0 0 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma exigua 69 28 34 36 17 19 21 30 Frustulia rhomboides 3 8 9 6 10 5 7 1 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 0 Frustulia saxonica 5 5 5 4 3 2 6 7 Gomphonema clevei 0 0 0 0 0 0 0 0 Kobayasia subtilissima 0 0 0 0 1 0 0 0 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 0 0 Navicula cryptocephala 1 5 2 2 0 1 1 1 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 2 3 0 1 3 1 2 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 0 1 0 0 0 0 0 0 Neidium hercynium 1 0 1 1 0 1 0 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 0 0 0 0 0 Nitzschia bryophila 5 5 2 1 2 3 1 1 Nitzschia perminuta 2 7 7 4 0 5 9 7 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 56 53 51 50 43 33 21 32 Pinnularia borealis 0 0 0 0 0 0 0 2 Pinnularia lapponica 0 1 1 0 0 1 0 0 Pinnularia rupestris 3 0 0 0 0 0 0 0 Pinnularia septentrionalis 0 1 3 3 2 1 2 2 Pinnularia subcapitata 0 0 0 1 0 0 0 0 Pinnularia viridis 0 2 2 0 2 1 4 0 Psammothidim helveticum 0 3 0 2 1 1 2 0 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 0 0 0 0 0 Psammothidium marginulatum 3 2 4 4 2 1 0 0 Pseudostaurosira brevistriata 0 0 0 0 0 31 49 51 Sellaphora pupula 0 1 0 3 5 1 1 6 Stauroneis neohyalina 1 5 3 4 1 0 2 3 Stauroneis obtusa 2 0 1 1 0 0 0 0 Stauroneis phoenicenteron 4 4 9 10 11 9 3 6 Stauroneis phoenicenteron v. brevis 3 5 5 8 4 7 4 1 Staurosira capucina 0 4 1 1 1 0 3 0 Staurosira capucina v. 0 0 0 0 0 0 0 0

105

capitellata Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 1 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 1 0 0 Staurosira construens v. venter 2 12 7 6 4 1 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 1 1 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 3 5 3 3 1 3 2 1 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 408 404 430 411 400 402 409 403

Interval (cm) 66 67 68 69 70 71 72 73 Achnanthes acares 4 18 10 15 17 8 27 11 Achnanthes curtissima 0 2 2 1 3 4 4 6 Achnanthes daonensis 0 0 0 0 0 0 0 0 Achnanthes holstii 2 0 2 0 1 0 1 1 Achnanthidium kriegeri 0 0 0 0 0 0 1 1 Achnanthidium minutissimum 2 0 0 0 0 0 0 0 Amphora copulata 0 0 0 0 0 0 0 2 Aulacoseira alpigena 9 5 4 3 15 34 11 22 Aulacoseira distans group 103 58 53 108 129 96 99 140 Aulacoseira lirata 7 7 1 1 1 8 7 1 Aulacoseira perglabra 2 3 1 3 16 12 9 18 Aulacoseira valida 8 5 10 20 15 19 16 23 Brachysira arctoborealis 1 0 0 0 1 0 0 0 Brachysira brebissonii 1 3 1 1 0 1 0 1 Brachysira intermedia 0 0 0 0 0 0 0 0 Brachysira microcephala 0 0 1 0 0 0 1 0 Caloneis aerophila 0 0 0 0 0 0 0 0 Cavinula pseudoscutiformes 0 0 1 1 1 2 0 2 Cavinula variostriata 2 0 0 2 3 5 1 2 Chamaepinnularia mediocris 0 0 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 0 0 Cyclotella bodanica 4 3 7 7 3 4 5 6 Cyclotella pseudostelligera 0 1 1 1 0 1 1 0 Cymbopleura amphicephala 0 0 1 5 5 0 0 0 Diadesmis laevissima 0 0 0 0 0 0 1 0 Encyonema gaeumannii 1 0 4 1 1 2 0 5 Encyonema hebridicum 0 0 0 0 0 1 0 1 Encyonema lunatum 0 4 1 0 0 0 1 0 Encyonema minutum 0 0 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 1 0 1 2 Encyonopsis cesatii 0 0 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 1 1 0 0 Eunotia faba 0 0 0 0 0 0 0 0 Eunotia fallax 0 0 0 0 0 1 0 0 Eunotia groenlandica 0 0 0 0 0 0 0 0 Eunotia incisa 1 0 0 0 0 0 0 0 Eunotia intermedia 0 0 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 0 1 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 0 0 0 0 Eunotia serra 0 0 0 0 1 0 0 0 Eunotia steineckii 0 0 0 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 0 0 Eunotia torula 0 0 0 0 1 1 0 0 Eunotia triodon 0 0 0 0 0 0 0 0

106

Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma exigua 15 17 11 21 22 42 47 28 Frustulia rhomboides 0 0 1 0 8 2 1 0 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 0 1 Frustulia saxonica 4 3 1 1 10 9 8 9 Gomphonema clevei 0 0 0 0 0 0 0 1 Kobayasia subtilissima 0 0 0 0 0 0 1 0 Meridion circulare 0 0 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 0 0 Navicula cryptocephala 2 5 5 1 5 4 3 5 Navicula gallica v. perpusilla 0 0 0 0 0 0 0 0 Navicula schmassmannii 1 2 0 0 3 3 5 2 Neidium ampliatum 0 0 0 0 0 0 0 0 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium dubium 0 0 0 0 0 0 0 0 Neidium hercynium 0 0 0 0 0 0 0 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Neidum affine 0 0 0 0 0 0 0 0 Nitzschia bryophila 3 0 2 0 3 4 5 1 Nitzschia perminuta 2 5 3 1 10 7 4 5 Peronia fibula 0 0 0 0 0 0 0 0 Pinnularia biceps 22 17 17 26 31 37 44 32 Pinnularia borealis 0 0 0 0 0 0 0 0 Pinnularia lapponica 0 0 0 0 1 0 0 0 Pinnularia rupestris 3 6 1 1 0 0 1 2 Pinnularia septentrionalis 1 0 1 2 1 2 1 0 Pinnularia subcapitata 0 0 0 0 0 0 2 0 Pinnularia viridis 1 0 0 0 0 0 0 0 Psammothidim helveticum 0 3 0 0 0 0 0 1 Psammothidium altaicum 0 0 0 0 0 0 0 0 Psammothidium bioretti 0 1 0 0 0 0 0 0 Psammothidium marginulatum 1 1 1 3 3 2 4 1 Pseudostaurosira brevistriata 203 249 248 170 118 106 95 61 Sellaphora pupula 3 0 5 3 8 4 0 4 Stauroneis neohyalina 3 3 3 2 3 2 2 2 Stauroneis obtusa 0 0 0 0 0 0 0 0 Stauroneis phoenicenteron 3 1 1 3 2 1 2 3 Stauroneis phoenicenteron v. brevis 0 0 3 0 0 1 0 1 Staurosira capucina 1 1 0 0 0 0 1 2 Staurosira capucina v. capitellata 0 0 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 0 0 Staurosira construens 1 1 6 1 7 0 5 2 Staurosira construens v. venter 0 0 0 0 0 1 0 5 Staurosirella pinnata 0 0 0 0 0 0 4 1 Stenoptorobia delicatissima 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 2 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 0 0 Tabellaria flocculosa 1 0 4 0 1 2 1 3 Tabellaria quadreseptata 0 0 0 0 0 0 0 0 TOTAL VALVES 417 424 413 406 451 429 423 416

Interval (cm) 74 75 76 77 78 79 Achnanthes acares 16 3 5 0 4 5 Achnanthes curtissima 2 0 0 0 2 0 Achnanthes daonensis 0 0 0 0 0 0 Achnanthes holstii 0 2 0 3 0 1 Achnanthidium kriegeri 0 2 3 1 0 0 Achnanthidium minutissimum 0 2 1 0 0 0 Amphora copulata 0 0 0 0 0 0 Aulacoseira alpigena 18 4 0 4 4 2 Aulacoseira distans group 111 48 41 4 56 26 Aulacoseira lirata 8 3 0 2 11 7 Aulacoseira perglabra 4 6 2 2 4 2

107

Aulacoseira valida 15 9 0 1 12 5 Brachysira arctoborealis 0 0 1 0 0 0 Brachysira brebissonii 2 2 4 6 2 0 Brachysira intermedia 0 0 2 0 0 0 Brachysira microcephala 0 0 0 0 0 0 Caloneis aerophila 0 0 1 0 0 0 Cavinula pseudoscutiformes 0 0 0 0 0 0 Cavinula variostriata 7 4 4 1 2 0 Chamaepinnularia mediocris 0 0 0 0 0 0 Chamaepinnularia soehrensis 0 0 0 0 0 0 Cyclotella bodanica 3 3 0 0 4 0 Cyclotella pseudostelligera 0 0 0 0 0 0 Cymbopleura amphicephala 2 1 0 1 1 1 Diadesmis laevissima 0 2 0 1 1 0 Encyonema gaeumannii 0 1 4 10 1 5 Encyonema hebridicum 0 0 0 0 0 0 Encyonema lunatum 0 0 0 0 0 0 Encyonema minutum 0 0 0 0 0 0 Encyonema silesiacum 0 0 0 0 0 0 Encyonopsis cesatii 0 0 0 0 0 0 Eunotia arcus 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 Eunotia denticulata 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 0 0 Eunotia faba 0 0 0 0 0 0 Eunotia fallax 0 0 0 0 0 0 Eunotia groenlandica 0 0 0 0 0 0 Eunotia incisa 0 0 0 0 0 0 Eunotia intermedia 0 0 0 0 0 0 Eunotia meisteri v. bidens 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 Eunotia naegelii 0 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 Eunotia praerupta 0 2 0 0 0 0 Eunotia praerupta v. bigibba 0 0 0 0 0 0 Eunotia rhomboidea 0 0 0 0 0 0 Eunotia serra 0 1 0 0 0 0 Eunotia steineckii 0 0 0 0 0 0 Eunotia tenella 0 0 0 0 0 0 Eunotia torula 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 0 Fragilariforma constricta 0 0 0 0 0 0 Fragilariforma exigua 45 98 92 149 168 251 Frustulia rhomboides 3 2 0 0 0 0 Frustulia rhomboides v. crassinervia 0 0 0 0 0 0 Frustulia saxonica 6 1 1 0 4 4 Gomphonema clevei 1 0 1 0 0 0 Kobayasia subtilissima 0 1 0 0 0 0 Meridion circulare 0 0 0 0 0 0 Microcostatus krasskei 0 0 0 0 0 0 Navicula cryptocephala 2 0 1 0 0 0 Navicula gallica v. perpusilla 0 0 0 0 0 0 Navicula schmassmannii 2 1 1 0 2 0 Neidium ampliatum 0 0 0 0 0 0 Neidium bisulcatum 0 0 0 0 0 0 Neidium dubium 0 0 0 0 0 0 Neidium hercynium 0 0 0 0 0 0 Neidium septentrionale 0 0 0 0 0 0 Neidum affine 0 0 0 0 0 0 Nitzschia bryophila 5 0 1 0 1 0 Nitzschia perminuta 1 4 1 3 0 0 Peronia fibula 0 0 0 0 0 0 Pinnularia biceps 58 143 194 157 62 44 Pinnularia borealis 0 0 0 0 1 0 Pinnularia lapponica 0 0 0 1 0 0 Pinnularia rupestris 1 0 1 0 0 0 Pinnularia septentrionalis 3 1 0 0 1 0 Pinnularia subcapitata 0 0 0 0 0 0

108

Pinnularia viridis 0 0 2 0 0 0 Psammothidim helveticum 0 0 1 0 0 0 Psammothidium altaicum 0 0 0 0 0 0 Psammothidium bioretti 0 0 0 0 0 0 Psammothidium marginulatum 1 1 1 1 2 1 Pseudostaurosira brevistriata 77 11 1 3 36 17 Sellaphora pupula 6 0 0 1 9 4 Stauroneis neohyalina 0 5 1 8 1 2 Stauroneis obtusa 0 0 0 0 0 0 Stauroneis phoenicenteron 1 0 0 0 0 2 Stauroneis phoenicenteron v. brevis 1 0 0 0 0 1 Staurosira capucina 7 2 1 0 0 0 Staurosira capucina v. capitellata 0 0 0 0 0 0 Staurosira capucina v. rumpens 0 0 0 0 0 0 Staurosira capucina v. vaucheriae 0 0 0 0 0 0 Staurosira construens 0 0 0 0 1 1 Staurosira construens v. venter 5 2 0 0 0 0 Staurosirella pinnata 2 1 0 0 1 1 Stenoptorobia delicatissima 0 0 0 0 0 0 Surirella linearis 0 0 0 0 0 0 Tabellaria fenestrata 0 0 0 0 0 0 Tabellaria flocculosa 4 6 7 8 4 11 Tabellaria quadreseptata 0 0 0 0 0 0 TOTAL VALVES 419 374 375 367 397 393

109

Appendix F. Raw diatom counts for the MIS 7 core from Lake CF8. Interval (cm) 199 200 201 202 203 204 205 206 Achnanthes holstii 0 0 0 0 0 0 0 0 Achnanthidium kriegeri 0 0 0 0 0 3 0 0 Achnanthidium minutissimum 0 0 0 0 0 2 0 2 Actinella punctata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 0 0 0 0 0 1 0 Aulacoseira distans group 7 0 0 7 179 35 41 155 Aulacoseira lirata 1 0 0 2 27 1 6 8 Aulacoseira perglabra 0 0 0 1 1 0 0 0 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira acrtoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonnii 0 0 0 0 0 3 2 1 Brachysira microcephala 0 0 0 0 2 6 0 0 Caloneis aerophila 0 0 0 0 0 1 2 2 Cavinula variostriata 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 0 0 0 0 0 0 Diadesmis laevissima 0 0 0 0 0 1 2 2 Ellerbeckia arenaria f. teres 0 0 0 0 0 0 0 0 Encyonema gaeumannii 0 0 0 0 1 0 0 4 Encyonema hebridicum 0 0 0 0 0 0 1 0 Eunotia arcus 0 0 0 0 1 4 0 0 Eunotia bilunaris 0 0 0 0 0 4 5 0 Eunotia denticulata 0 0 0 0 0 0 0 1 Eunotia diodon 0 0 0 0 0 0 0 0 Eunotia exigua group 0 0 0 0 0 8 5 2 Eunotia faba 0 0 0 1 0 2 0 0 Eunotia fallax 0 0 0 0 0 1 0 0 Eunotia groenlandica 0 0 0 0 1 0 3 0 Eunotia incisa 0 0 0 0 0 0 0 0 Eunotia minor 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 0 0 0 0 Eunotia paludosa 0 0 0 0 0 31 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 0 0 Eunotia praerupta 0 0 0 0 0 1 5 1 Eunotia praerupta v. bigibba 0 0 0 0 0 3 0 0 Eunotia rhomboidea 2 0 0 0 8 12 8 69 Eunotia steineckii 0 0 0 0 0 0 0 0 Eunotia triodon 0 0 0 0 0 2 4 2 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma virescens 2 0 0 0 28 4 2 7 Frustulia rhomboides 1 0 0 1 24 0 4 8 Kobayasia subtilissima 0 0 0 0 0 0 0 0 Navicula gallica v. laevissima 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium affine 0 0 0 0 0 7 0 0 Neidium ampliatum 0 0 0 0 8 4 0 6 Neidium bisulcatum 0 0 0 0 0 0 0 0 Neidium septentrionale 0 0 0 0 0 0 0 0 Nitzschia fonticola 0 0 0 0 0 0 0 0 Nitzschia perminuta 0 0 0 0 1 0 0 0 Pinnularia biceps 0 0 0 0 2 10 6 12 Pinnularia borealis 0 1 0 0 0 0 0 0 Pinnularia intermedia 0 0 0 0 0 0 0 0 Pinnularia lapponica 0 0 0 0 0 0 0 0 Pinnularia microstauron 0 0 0 0 0 0 0 0 Pinnularia rupestris 0 0 0 1 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidim helveticum 0 0 0 0 4 76 15 1 Psammothidium marginulatum 0 0 0 0 16 146 65 90 Psammothidium ventralis 0 0 0 0 0 0 0 0

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Pseudostaurosira brevistriata 0 0 0 0 1 0 0 0 Stauroneis neohyalina 0 0 0 0 0 0 0 0 Stauroneis obtusa 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 1 0 0 0 Staurosira construens v. venter 0 0 0 0 0 0 0 1 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 0 0 0 1 0 0 0 Tabellaria flocculosa 0 0 0 0 2 0 1 1 Tabellaria quadriseptata 0 0 0 0 0 0 0 0 TOTAL 13 1 0 13 308 367 178 375

Interval (cm) 207 208 209 210 211 212 213 214 Achnanthes holstii 1 0 0 0 0 0 0 0 Achnanthidium kriegeri 1 0 1 0 0 0 0 1 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Actinella punctata 0 0 0 0 0 0 0 0 Aulacoseira alpigena 0 0 0 0 0 0 0 0 Aulacoseira distans group 102 106 191 103 106 289 268 242 Aulacoseira lirata 29 11 4 15 16 4 2 12 Aulacoseira perglabra 0 0 0 0 0 0 0 0 Aulacoseira valida 0 0 0 0 0 0 0 0 Brachysira acrtoborealis 0 0 0 0 0 0 0 0 Brachysira brebissonnii 2 0 2 0 1 0 0 2 Brachysira microcephala 0 0 0 0 0 0 0 0 Caloneis aerophila 0 2 1 0 3 2 1 2 Cavinula variostriata 0 0 0 0 0 0 0 0 Cymbopleura amphicephala 0 0 0 0 0 0 0 0 Diadesmis laevissima 4 4 3 1 1 1 3 0 Ellerbeckia arenaria f. teres 0 0 0 0 0 0 0 0 Encyonema gaeumannii 0 1 1 1 0 0 2 0 Encyonema hebridicum 0 0 0 2 0 0 0 3 Eunotia arcus 1 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 2 Eunotia denticulata 0 0 0 1 2 0 1 0 Eunotia diodon 0 0 0 0 0 0 0 0 Eunotia exigua group 2 9 8 7 0 2 1 0 Eunotia faba 1 2 4 0 0 0 0 1 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 5 3 0 0 0 0 0 Eunotia incisa 0 0 0 0 0 0 0 0 Eunotia minor 0 0 0 0 0 0 0 0 Eunotia muscicola v. muscicola 0 0 0 0 2 0 0 0 Eunotia paludosa 0 4 1 0 0 0 0 0 Eunotia parallela v. parallela 0 0 0 0 0 0 0 1 Eunotia praerupta 0 3 0 1 3 0 0 1 Eunotia praerupta v. bigibba 0 0 0 0 0 0 0 0 Eunotia rhomboidea 40 28 10 23 20 5 7 12 Eunotia steineckii 0 0 0 0 0 0 0 0 Eunotia triodon 1 2 0 3 0 0 4 0 Fragilariforma constricta 0 0 0 0 0 0 0 0 Fragilariforma virescens 10 9 5 11 7 1 2 4 Frustulia rhomboides 1 2 4 7 6 3 7 12 Kobayasia subtilissima 0 0 0 0 0 0 0 0 Navicula gallica v. laevissima 0 0 0 0 0 0 0 0 Navicula schmassmannii 0 0 0 0 0 0 0 0 Neidium affine 0 0 0 0 0 0 0 0 Neidium ampliatum 13 15 7 12 5 3 4 1 Neidium bisulcatum 0 0 0 1 0 0 0 0 Neidium septentrionale 0 1 0 0 0 0 0 0 Nitzschia fonticola 0 0 0 0 0 0 0 0

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Nitzschia perminuta 0 0 0 0 0 0 0 1 Pinnularia biceps 18 27 43 44 69 21 5 11 Pinnularia borealis 0 1 0 2 1 2 0 0 Pinnularia intermedia 0 0 0 0 0 0 0 0 Pinnularia lapponica 3 1 0 0 0 0 0 0 Pinnularia microstauron 0 0 0 0 0 0 0 3 Pinnularia rupestris 0 0 0 0 0 0 0 0 Pinnularia subcapitata 0 0 0 0 0 0 0 0 Psammothidim helveticum 0 1 0 10 2 0 1 0 Psammothidium marginulatum 208 174 133 157 164 86 100 62 Psammothidium ventralis 0 0 0 0 0 0 0 0 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 0 0 1 2 0 0 0 Stauroneis obtusa 0 0 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 0 0 0 1 0 0 0 0 Staurosirella pinnata 0 0 0 0 0 0 0 0 Surirella linearis 0 1 0 1 0 0 0 0 Tabellaria flocculosa 6 2 0 4 1 0 0 2 Tabellaria quadriseptata 0 0 0 0 0 0 0 0 TOTAL 444 411 421 408 411 419 408 375

Interval (cm) 215 216 217 218 219 220 221 222 Achnanthes holstii 0 0 2 0 1 0 3 0 Achnanthidium kriegeri 0 0 0 0 1 1 3 0 Achnanthidium minutissimum 0 0 0 0 0 0 0 0 Actinella punctata 0 0 1 0 0 0 0 0 Aulacoseira alpigena 2 0 0 0 2 2 4 0 Aulacoseira distans group 268 57 100 320 167 253 63 316 Aulacoseira lirata 7 15 33 1 34 22 21 4 Aulacoseira perglabra 0 0 0 0 0 0 0 0 Aulacoseira valida 0 0 0 0 2 0 0 0 Brachysira acrtoborealis 0 0 0 0 4 3 0 0 Brachysira brebissonnii 0 2 6 0 7 2 0 0 Brachysira microcephala 0 0 0 3 0 1 0 1 Caloneis aerophila 0 0 1 2 4 0 1 1 Cavinula variostriata 0 0 0 0 1 0 0 0 Cymbopleura amphicephala 0 1 2 0 0 0 0 0 Diadesmis laevissima 1 6 11 0 5 5 24 6 Ellerbeckia arenaria f. teres 0 0 1 0 1 0 0 0 Encyonema gaeumannii 1 2 1 2 2 2 1 0 Encyonema hebridicum 1 0 2 0 2 0 0 0 Eunotia arcus 0 0 0 0 0 0 0 0 Eunotia bilunaris 0 0 0 0 0 0 0 0 Eunotia denticulata 0 0 0 1 0 0 0 0 Eunotia diodon 0 0 0 0 1 0 0 0 Eunotia exigua group 8 1 1 0 1 4 0 1 Eunotia faba 0 0 0 0 0 1 0 0 Eunotia fallax 0 0 0 0 0 0 0 0 Eunotia groenlandica 0 0 1 0 3 0 1 0 Eunotia incisa 0 0 0 0 1 2 2 0 Eunotia minor 0 0 0 0 0 0 1 0 Eunotia muscicola v. muscicola 0 0 1 0 1 1 0 1 Eunotia paludosa 0 0 0 0 0 0 0 0 Eunotia parallela v. parallela 0 4 0 0 0 3 0 0 Eunotia praerupta 3 0 9 1 6 5 17 0 Eunotia praerupta v. bigibba 4 0 0 0 0 0 2 0 Eunotia rhomboidea 4 5 5 3 7 3 4 0 Eunotia steineckii 0 0 2 0 0 1 0 0 Eunotia triodon 3 3 5 1 1 3 4 1

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Fragilariforma constricta 1 0 0 0 0 0 0 0 Fragilariforma virescens 6 7 43 0 57 15 16 5 Frustulia rhomboides 8 7 8 13 14 20 13 10 Kobayasia subtilissima 0 3 1 0 0 0 0 0 Navicula gallica v. laevissima 0 0 0 0 0 1 0 0 Navicula schmassmannii 0 0 0 0 0 0 1 0 Neidium affine 1 0 0 0 0 0 0 1 Neidium ampliatum 5 11 4 0 5 1 4 3 Neidium bisulcatum 0 0 1 0 0 0 0 0 Neidium septentrionale 0 0 0 0 1 1 0 0 Nitzschia fonticola 0 0 0 0 0 0 0 1 Nitzschia perminuta 0 0 0 0 1 0 0 0 Pinnularia biceps 15 113 23 11 22 11 51 16 Pinnularia borealis 0 1 3 0 3 6 4 2 Pinnularia intermedia 0 0 0 0 0 0 1 0 Pinnularia lapponica 0 0 0 0 0 0 0 0 Pinnularia microstauron 1 0 5 0 1 2 1 0 Pinnularia rupestris 0 0 0 0 2 0 0 0 Pinnularia subcapitata 0 1 0 0 2 8 11 0 Psammothidim helveticum 5 3 7 12 15 2 2 13 Psammothidium marginulatum 50 31 20 48 35 33 16 51 Psammothidium ventralis 0 0 0 0 0 0 1 0 Pseudostaurosira brevistriata 0 0 0 0 0 0 0 0 Stauroneis neohyalina 0 1 0 0 0 1 0 0 Stauroneis obtusa 0 2 0 0 0 0 0 0 Staurosira construens 0 0 0 0 0 0 0 0 Staurosira construens v. venter 1 0 0 0 1 0 0 0 Staurosirella pinnata 0 0 3 0 1 0 0 0 Surirella linearis 1 0 1 0 0 1 0 0 Tabellaria flocculosa 1 3 6 6 7 2 3 1 Tabellaria quadriseptata 0 0 1 0 0 0 0 0 TOTAL 397 279 310 424 421 418 275 434

Interval (cm) 223 Achnanthes holstii 0 Achnanthidium kriegeri 0 Achnanthidium minutissimum 0 Actinella punctata 0 Aulacoseira alpigena 0 Aulacoseira distans group 334 Aulacoseira lirata 5 Aulacoseira perglabra 0 Aulacoseira valida 0 Brachysira acrtoborealis 0 Brachysira brebissonnii 3 Brachysira microcephala 1 Caloneis aerophila 2 Cavinula variostriata 0 Cymbopleura amphicephala 0 Diadesmis laevissima 0 Ellerbeckia arenaria f. teres 0 Encyonema gaeumannii 2 Encyonema hebridicum 0 Eunotia arcus 0 Eunotia bilunaris 0 Eunotia denticulata 0 Eunotia diodon 0 Eunotia exigua group 0 Eunotia faba 0 Eunotia fallax 0 Eunotia groenlandica 0 Eunotia incisa 0 Eunotia minor 0 Eunotia muscicola v. 1

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muscicola Eunotia paludosa 0 Eunotia parallela v. parallela 0 Eunotia praerupta 1 Eunotia praerupta v. bigibba 0 Eunotia rhomboidea 2 Eunotia steineckii 0 Eunotia triodon 0 Fragilariforma constricta 0 Fragilariforma virescens 5 Frustulia rhomboides 14 Kobayasia subtilissima 0 Navicula gallica v. laevissima 0 Navicula schmassmannii 0 Neidium affine 0 Neidium ampliatum 4 Neidium bisulcatum 0 Neidium septentrionale 0 Nitzschia fonticola 0 Nitzschia perminuta 0 Pinnularia biceps 14 Pinnularia borealis 1 Pinnularia intermedia 0 Pinnularia lapponica 0 Pinnularia microstauron 0 Pinnularia rupestris 0 Pinnularia subcapitata 0 Psammothidim helveticum 9 Psammothidium marginulatum 45 Psammothidium ventralis 0 Pseudostaurosira brevistriata 0 Stauroneis neohyalina 0 Stauroneis obtusa 0 Staurosira construens 0 Staurosira construens v. venter 0 Staurosirella pinnata 0 Surirella linearis 0 Tabellaria flocculosa 6 Tabellaria quadriseptata 0 TOTAL 449

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Appendix G. Age model developed for the surface core based on 210Pb and 14C dates, published by Thomas et al. 2008.

Depth (cm) Years BP 2005

210Pb and 14C Years BP 2005 Modeled ages

0.125 0.01 0.375 4.01 0.625 8.59 0.875 15.21 1.125 21.50 1.375 27.34 1.625 32.36 1.875 43.16 2.125 57.11 2.375 70.06 2.625 81.76 2.875 100.26 3.125 120.78 3.375 145 3.625 174 3.875 220 4.125 289 4.375 378 4.625 482 4.875 590 5.125 694 5.375 786 5.625 878 5.875 955 6.125 1029 6.375 1103 6.625 1174 6.875 1244 7.125 1312 7.375 1378 7.625 1443 7.875 1506 8.125 1567 8.375 1628 8.625 1686 8.875 1743 9.125 1799 9.375 1853 9.625 1906 9.875 1958

10.125 2008 10.375 2057 10.625 2105 10.875 2151 11.125 2197 11.375 2241 11.625 2284 11.875 2326 12.125 2367 12.375 2406 12.625 2445 12.875 2483 13.125 2520 13.375 2556 13.625 2591 13.875 2625 14.125 2658 14.375 2691 14.625 2722 14.875 2753 15.375 2799

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15.875 2856 16.375 2912 16.875 2965 17.375 3016 17.875 3066 18.375 3114 18.875 3160 19.375 3206 19.875 3251 20.375 3295 20.875 3339 21.375 3383 21.875 3428 22.375 3472 22.875 3517 23.375 3563 23.875 3611 24.375 3659 24.875 3709

25.5 3788

Figure A. 210Pb dates for 0 cm to 3.125 cm. Error bars represent 1σ.

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The polynomial for 3.375 cm to 5.375 cm depth is age = 3.07x6 - 59.045x5 + 378.83x4 - 562.23x3

- 3437.8x2 + 14499x – 15850. The polynomial for below 5.625 cm depth is age = 0.3178x3 -

19.919x2 + 504.12x – 1384. These polynomial functions were developed and published by

Thomas et al. (2008); while the use of a sixth-order polynomial for the smoothed connection

between the 210Pb and 14C dates assumes accuracy that cannot be known, a linear model between

these two dates provides similar ages. Therefore, for consistency, the published model was used

here.

Figure B. Complete age model from 0 cm to 25.5 cm based on 210Pb dates (Figure A) and three 14C dates. Thomas et al. 2008 used a smoothed connection between the oldest 210Pb date and the youngest 14C date, and a third-order polynomial for the remainder of the core. Note that diatom analysis did not continue through the entire depth of the surface core, and so the modeled dates were used to a depth of 19.625 cm.

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Appendix H. Age model developed for the Holocene core based on 14C dates, developed and published by Axford et al. 2008. * Each calibrated age is the midpoint ± 1σ range calculated using CALIB 5.0.2.

Depth (cm) δ 14C Fraction modern 14C age (14C yr BP)

Calibrated age (cal yr BP) *

2 -24.8 0.9111±0.0040 748±35 695±35 31 -26.6 0.6766±0.0052 3138±62 3360±190 50 -29.1 0.5596±0.0028 4664±41 5440±130 58 -29.2 0.4677±0.0009 6105±20 7025±125

66.5 -24.7 0.3937±0.0009 7490±20 8295±85 70.5 -21.7 0.3962±0.0009 7440±20 8260±70

71 -24.2 0.3996±0.0034 7368±68 8185±155 77 -24.0 0.3836±0.0012 7695±30 8480±60 84 -24.6 0.3515±0.0008 8400±20 9410±75 88 -29.0 0.3530±0.0022 8365±50 9375±115 98 -27.8 0.3215±0.0008 9115±25 10300±75

107 -30.5 0.3133±0.0017 9320±45 10490±185 107.5 -21.4 0.3119±0.0011 9360±30 10590±85

113 -16.2 0.2794±0.0009 10245±30 11965±140 121 -26.5 0.3457±0.0037 8532±86 9505±195

The age model splices two different polynomial functions, a third-order polynomial from 0 cm to

60 cm and a second-order polynomial from 60 cm to the base of the core, to construct one

composite age model. The two deepest ages are inverted, and thus not fit to the polynomial.

The polynomial for 0 cm to 60 cm depth is age = (-0.01x3) + (1.3504x2) + (62.599x) + 523.22.

The polynomial for below 60 cm depth is age = (-0.3632x2) + (138.62x) + 59.666.

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Figure A. 14C chronology (two ages shown as open triangles are excluded from the polynomial fit). 2σ calibrated age ranges are shown for each age. Dashed gray lines are 95% confidence intervals. From Axford et al. 2008.

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Appendix I. 14C dates for two different interstadial gyttja units from two cores, published by Briner et al. 2007a.

Core Depth (cm) δ 14C Fraction modern 14C age (14C yr BP) 04-CF8-02a 80 -22.1 0.00474 ±0.00063 43000 ±1070 04-CF8-02a 81 -23.9 0.0140±0.0010 34290 ±570

02-CF8 164 -22.3 0.00260 ±0.00020 47810 ±400

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Appendix J. OSL dates for the LIG and MIS 7 cores, published by Briner et al. 2007a. Core Depth

(cm) Equivalent Dose

(Gy) * U (ppm)

** Th (ppm)

** K2O (%)

** A-value H2O (%) Organic

and BSiO2 (%)

Cosmic dose

(Gy/ka) **

Dose rate (Gy/ka)

OSL age (ka)

05-CF8-01 90- 95 425.073 ± 2.40 2.0 ± 0.1 35.1 ± 0.1 2.23 ± 0.01 0.13 ± 0.01 60 ± 10 25 ± 5 0.05 ± 0.01 4.38 ± 0.28 97.15 ± 0.91

05-CF8-01 90- 95 460.94 ± 2.95 2.0 ± 0.1 35.1 ± 0.1 2.23 ± 0.01 0.13 ± 0.01 60 ± 10 25 ± 5 0.05 ± 0.01 4.38 ± 0.28 105.35 ± 9.85

05-CF8-01 140-145 899.77 ± 8.28 3.8 ± 0.1 66.0 ± 0.1 1.97 ± 0.01 0.12 ± 0.01 60 ± 10 12 ± 3 0.04 ± 0.01 7.39 ± 0.41 121.71 ± 12.08

05-CF8-01 213-218 (>)1260.44 ± 7.45 2.4 ± 0.1 37.3 ± 0.1 3.78 ± 0.04 0.12 ± 0.01 50 ± 10 4 ± 2 0.04 ± 0.01 6.49 ± 0.35 (>)194.12 ± 18.92

* Multiple aliquot regenerative dose method.

** U, Th and K20 content by ICP-MS; includes a cosmic ray dose rate from calculations of Prescott and Hutton (1994) (see Briner et al. 2007a).

All errors are at 1σ. Analyses by the Luminescence Dating Research Laboratory, University of Illinois at Chicago.