Lake and Landscape Features Shaping Aquatic Macrophyte Communities in the Undisturbed Lakes of Isle Royale National Park, Michigan, USA

Angela De Palma-Dow Kendra S.Cheruvelil

Michigan State University

East Lansing, MI

1

What are aquatic macrophytes?

2

Background and Introduction

3

Macrophyte communities in lakes: Habitat structural complexity

Shelter refuge from predators

Shoreline & sediment stabilization

Oxygen production

Nutrient cycling

e.g., Sousa, Thomas & Murphy 2011, Mastrantuono & Mancinelli 2005; Scheffer 1998; Lodge 1985

4

5

Why we care: High macrophyte production in ecosystems

From: Wetzel 2001

Native macrophyte communities: Repositories for biodiversity

Natural inventories

Rare & threatened species

Range, distribution and DNA

Essential to gauge changes over time

Climate changes & shifts

Introduction of invasive species

Natural variation of communities

- succession, herbivory, seasonal patterns

e.g., Giller et al. 2004; MI Natural Features Inventory; MEA 2005; O’Hare 2012.

7

How do we measure macrophyte communities?

8

Measuring macrophyte communities Richness (# species)

9

Measuring macrophyte communities Richness (# species) Diversity (richness + abundance)

10

Measuring macrophyte communities Richness (# species) Diversity (richness + abundance) Structure (growth form)

11

What shapes macrophyte communities?

12

Shaping macrophyte communities 1) Introductions / dispersal of species - Physical aquatic connections 2) Establishment and growth - Lake and landscape features

13

Research question: What shapes the inland lake macrophyte communities on Isle Royale National Park?

1) Introductions and dispersal potential 2) Establishment and growth potential

e.g. Kissoon et al 2013;Akasaka & Takamura 2012; O’Hare et al. 2012; Sousa, Thomas &Murphy 2011, Leibold et al. 2004

14

Expectations: Introduction and dispersal potential

Few macrophyte studies • Disturbed, altered, engineered or invaded systems

• Richness higher in connected ponds • Lakes close together had similar community composition

Need for more information • Natural, undisturbed, protected lakes

(e.g. Akasaka & Takamura 2012; O’hare et al. 2012; Dahlgren & Ehrlen 2005; Larson et al. 1995; Van Geest et al. 2003) 15

Credit: Thomas Kitchin & Vict / All Canada Photos / SuperStock

Expectations: Establishment and growth potential LOTS of studies

• Increased lake area = higher richness • Irregular lake shape = higher richness • Increased clarity = higher richness &

diversity

Less studied

• Water color • Sediment nutrients • Macrophyte diversity & structure

Need for more information • Natural, undisturbed, protected lakes

SDF = 1

SDF =50

16

Vestergaard and San-Jensen 2000

Macrophyte communities on Isle Royale…

17

http://www.noaanews.noaa.gov/stories2011 18

USGS 1968

• Reference condition of native communities • Pre-invasion status • Home to rare / threatened species • Macrophytes serve as food & habitat to

island wildlife

Why Isle Royale?

C: B. Bergman and J. Bump 2011

Methods

20

Approach: Comparative field study 15 inland lakes

• Sampled summers 2012 & 2013

• Relatively deep (>2m)

• Relatively permanent

Predictors: Dispersal & introduction potential

1. Surface hydrologic connectivity

• # of Inflows • # of Outflows • Position in lake chain

(e.g. Yannarell & Triplett 2005; Soranno et al 1999; Kratz 1997)

2. Lake characteristics

• Lake Area, Watershed Area

• Max Depth

• SDF (lake shape)

• Water & sediment chemistry

– NH4, TP, Alkalinity

• Water Color

• Water Clarity (Secchi disk)

Predictors: Establishment & growth

(e.g. Capers et al. 2009; Hakanson & Boulion 2002)

Response macrophyte variables

• Richness – Number of species in lake

• Diversity (e.g. Chiarucci et al 2011)

– Shannon Evenness Index emphasizes rarity

– Inverse Simpson Index emphasizes commonality

• Structure: % Growth form Emergent Submersed Floating leaf

24

Methods: Macrophyte sampling

Snorkel surveys of each lake:

• Four quadrants

• (4) 50m transects

– 8 quadrats (0.5 m 2)

• Each quadrat

– Est. % occurrence

– Use Braun-Blanquet cover classes (1964)

25

Methods: Macrophyte sampling

• Richness : all species encountered = present

• Diversity: calculated from % occurrence

• Structure: % Growth form calculated from richness values

26

Methods: Statistical analysis

Richness

Diversity - Shannon Evenness Index

Diversity - Inverse Simpson Index

1. Calculate macrophyte metrics

3. Determine dispersal vs.

establishment ID most important & recurring predictors

Partial least square regression (PLSR)

• Consolidate predictors into components

• Use components in regression

• One PLSR for each response variable

2. Model macrophyte metrics as function

of predictors

27

Results

28

Results: Macrophyte Richness

25 24

21 20

17 17 16 15 13

24 22

19

13 12

9

0

5

10

15

20

25

30

Ric

hn

ess

(#

of

spe

cie

s )

Connected Lakes

Isolated Lakes

29

Results: Macrophyte Diversity

Lake Name Shannon Evenness

(rare) Lake name

Inverse Simpson (common)

Feldtman 0.42 Least diverse

Feldtman 1.69 Benson 0.60 Benson 3.13 Ojibway 0.61 Ojibway 3.15 LeSage 0.73 LeSage 3.85 Beaver 0.74 Desor 4.49

Livermore 0.75 Livermore 4.63 Angelworm 0.78 Beaver 5.31

Otter 0.79 Angelworm 5.97 Mason 0.81 Patterson 7.21 Richie 0.82 Richie 7.24 Desor 0.83 McDonald 7.88 Ahmik 0.83 Mason 8.05

Patterson 0.84 Ahmik 8.22 McDonald 0.84

Most diverse Otter 8.26

Chickenbone 0.87 Chickenbone 10.16

MEAN 0.8 MEAN 5.9 SD 0.1 SD 2.3

30

Results: Macrophyte Diversity

Lake Name Shannon Evenness

(rare) Lake name

Inverse Simpson (common)

Feldtman 0.42 Least diverse

Feldtman 1.69 Benson 0.60 Benson 3.13 Ojibway 0.61 Ojibway 3.15 LeSage 0.73 LeSage 3.85 Beaver 0.74 Desor 4.49

Livermore 0.75 Livermore 4.63 Angelworm 0.78 Beaver 5.31

Otter 0.79 Angelworm 5.97 Mason 0.81 Patterson 7.21 Richie 0.82 Richie 7.24 Desor 0.83 McDonald 7.88 Ahmik 0.83 Mason 8.05

Patterson 0.84 Ahmik 8.22 McDonald 0.84

Most diverse Otter 8.26

Chickenbone 0.87 Chickenbone 10.16

MEAN 0.8 MEAN 5.9 SD 0.1 SD 2.3

31

Results: Structure - % Growth Form

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Ric

hie

Ch

icke

nb

on

e

Ott

er

Mas

on

Ah

mik

Live

rmo

re

Ojib

way

Bea

ver

Pat

ters

on

An

gelw

orm

McD

on

ald

Ben

son

LeSa

ge

Feld

tman

Des

or

Am

ou

nt

of

gro

wth

typ

e in

lake

FloatingLeaf

Emergent

Submersed

32

Inflow

Lake Area

SDF

Secchi Depth

TP, Water

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

Dir

ect

ion

an

d e

ffe

ct c

orr

ect

ed

pro

po

rtio

n o

f va

riat

ion

exp

lain

ed

by

vari

able

Example Results: Most important variables for explaining variation in response variable

33

(>15%)

% Variation seen in Y from X (First component only)

Connectivity Metrics

Lake and Landscape Metrics

Chemistry

Results: Macrophyte Richness

# inflow SDF

TP, Water

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

Dir

ect

ion

an

d e

ffe

ct c

orr

ect

ed

pro

po

rtio

n o

f va

riat

ion

exp

lain

ed

by

vari

able

50% variation, p < 0.001 Chain Location

# inflow

# outflow

Depth Max

Lake Area

SDF

Watershed Area

Alkalinity

Water Color

Secchi Depth

NH4, Water

TP, Water

TP, Sediment

34

Alkalinity

TP, Sediment -0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40 Shannon Evenness (rare): 60% variation, p<0.001 Chain Location

# inflow

# outflow

Depth Max

Lake Area

SDF

Watershed Area

Alkalinity

Water Color

Secchi Depth

NH4, Water

TP, Water

TP, Sediment

Alkalinity

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40Simpson Inverse (common): 56% variation, p<0.001

Results: Macrophyte diversity D

ire

ctio

n a

nd

eff

ect

co

rre

cte

d p

rop

ort

ion

of

vari

atio

n e

xpla

ined

by

vari

able

fo

r co

mp

on

ent

1

35

Results: Structure (% growth form) D

ire

ctio

n a

nd

eff

ect

co

rre

cte

d p

rop

ort

ion

of

vari

atio

n e

xpla

ined

by

vari

able

fo

r co

mp

on

ent

1

Chain Location

# outflow

Lake Area -0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

Titl

e

Emergent: 57% variation, p<0.01

# outflow

TP, Water

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4Floating Leaf: 56% variation, p<0.001

Lake Area

Water Color -0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

Submersed: 43% variation, p<0.01

36

37

Discussion and Conclusions

Summary: What shapes the inland

lake macrophyte communities on Isle Royale National Park?

• Intro/dispersal AND Establishment / growth

• Predictors differ by macrophyte metric

– Richness

– Diversity

– Structure

38

0

5

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25

0.00

0.10

0.20

0.30

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0.50

0.60

0.70

0.80

0.90

1.00

0 50 100 150 200 250

Shan

no

n E

ven

ne

ss

Ric

hn

ess

Total Phosphorous (ug/L)

Shannon Eveness (Sediment TP) Lake Richness (Water TP)

Discussion: Species Richness, diversity and Phosphorous

39

0

5

10

15

20

25

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 50 100 150 200 250

Shan

no

n E

ven

ne

ss

Ric

hn

ess

Total Phosphorous (ug/L)

Shannon Eveness (Sediment TP) Lake Richness (Water TP)

Mainland Michigan CLMP TP range

Discussion: Species Richness, diversity and Phosphorous

40

Discussion: Species diversity and alkalinity

41 e.g. Vestergaard & Sand-Jenson 2000

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00

0.10

0.20

0.30

0.40

0.50

0.60

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0.80

0.90

1.00

0 50 100 150 200

Inve

rse

Sim

pso

n

Shan

no

n E

ven

ne

ss

Alkainity in CaCo3 ppm

Shannon Eveness Inverse Simpson

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00

0.10

0.20

0.30

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0.50

0.60

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0.80

0.90

1.00

0 50 100 150 200

Inve

rse

Sim

pso

n

Shan

no

n E

ven

ne

ss

Alkalinity in CaCo3 ppm

Shannon Eveness Inverse Simpson Mainland Michigan STORET & DNR (1979-2004)

Discussion: Species diversity and alkalinity

42 e.g. Vestergaard & Sand-Jenson 2000

Discussion: Significance of comparing Isle Royale to other lakes

• Relatively undisturbed lakes vs. areas where we have most information

– Invasive presence

– Shoreline development

• Influence of natural connectivity

– No boating traffic

– Reference conditions

43

Conclusions

• Macrophyte communities shaped by both introduction/dispersal and establishment/growth “shaper” variables

– Include dispersal (connectivity) in future studies

• Multiple response metrics are important (richness, diversity, structure)

– Characterize different aspects of communities

– Shaped by lake, landscape, and connectivity variables

• Sample sediment nutrients and water color 44

Thank you!

Field and Lab Techs Kim Schoch

Sarah Schaffer Charlotte Lee

Jennifer Hollen Hannah Meiklejohn

Kaitlin Clark Haley Sisson

Rachel Mistak Stephen Rivard

Committee Members and

Analysis support Kendra Cheruvelil

Garret Crow Kim Scribner

Paul Bourdeau

Limnology Lab at Michigan State University!

National Park Service Staff Mark Romanski, Paul Brown, Val Martin & Erin Leinart Additional Support: Dr. Joe Bump & Brenda Bergman (Mich Tech)

MiCorps’ Jo Latimore

45

Thank you!

Questions?

46

47

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0 2 4 6 8 10 12

Ric

hn

ess

an

d S

imp

son

Div

ers

ity

Chl-A Concentrations mg m-3

Richness Simpson

Simpson R2=0.19 P= 0.46

Richness R2=0.11 P= 0.59

Did we do a good job of sampling the diversity in the communities?

48

Generally, could have sampled more lakes but, as we get to the 12th and the 14th lake, the error bars on the curve are getting smaller, meaning that a plateau is close and probably would be more defined had we sampled a few more lakes. We know that these lakes had high numbers of rare species (ex: we found at least one species that was only found in one or two lakes).

Accuracy assessment results

• Would my diversity metrics results differ if I sampled my lakes based on size and not uniformly?

• Ex. Richie lake instead of 4 transect, sampled 8 transects

49

How similar or dis-similar are these communities? Bray-Curtis clustering for both the plant species found in each lake and lake type based on environmental variables

50

Feldtman Benson Richie

Desor Angelworm

Chickenbone Otter

Ojibway LeSage Mason

Patterson Ahmik

McDonald Beaver Livermore

0.3 0.5 0.7 0.9

Ma

cro

ph

yte

Ab

un

dan

ce

Bray-Curtis dissimilarity

Feldtman Chickenbone Livermore

Desor Richie

Angelworm LeSage

Beaver McDonald

Mason Ojibway Benson Otter

Ahmik Patterson

0.0 0.2 0.4

Pre

dic

tors

Bray-Curtis dissimilarity