Limnology

3

Stream Organisms

Limnology

4

The stream organisms are divided into three

sections:

Autotrophs

Invertebrates

Fish

Stream organisms

Limnology

5

Autotrophs

Autotrophs

Autotrophs

Limnology

6

Lotic phytoplankton :

Algae

Protozoans

Cyanobacteria

phytoflagellates

(euglenophyta)

Biodidac

Lotic phytoplankton

Limnology

7

Benthic autotrophs

Benthic autotrophs

periphyton

benthic

autotrophs 3

(epilithon)

(epipelon)

(epiphyton)

Limnology

8

Periphyton

Periphyton

(heterotrophic microbes)

Limnology

9

Attached and benthic populations

blue-green algae

(epilithic forms),

(epiphytic forms)

(epipelic forms)

diatoms

green algae blue-greens

blue-green algae

(cyanobacteria)

Diatoms

Biodidac

green algae

(chlorophyta)

Limnology

10

Seasonal succession in periphyton communities

Diatoms

winter, spring, and early

summer

Green algae cyanobacteria

Benthic autotrophs

www.urbanrivers.org/web_images/diatoms.gif

Limnology

11

Distribution of autotrophs: Lakes vs rivers

phytoplankton

photic zone phytoplankton

Limnology

12

Algal primary productivity

35-95 %

,

Limnology

13

Macrophytes

Westlake (1975a) identified four primary growth forms:

1) Emergents

2) Floating-leaved species

3) Free-floating species

4) Submerged species

Limnology

14

Macrophyte growth forms

Emergents:

Floating-leaved:

Free-floating:

(tropical)

Submerged: (

,

)

Emergent

Floating-leaved

Free-floating

Submerged

Limnology

15

Aquatic macrophytes

( )

wetland

Macrophyte growth forms Limnology

16

Basic macrophyte structure

,

,

(Hynes, 1970;

Westlake, 1975a).

Limnology

17

Patchy distribution of macrophytes

( )

Limnology

18

Macrophyte consumers

macrophyte

primary production herbivory,

dissolved organic

matter

Herbivory

, ,

carp, (Westlake,

1975b)

Limnology

19

Stream invertebrates

benthic

macroinvertebrate

macroinvertebrate , crayfish,

Macroinvertebrates ,

5 microns (

, )

Limnology

20

Insects

taxonomy

Limnology

21

Morphological adaptations to running water

Limnology

22

Morphological adaptations to running water

Limnology

23

Classification of insects Limnology

24

Aquatic insect orders

Limnology

25

Aquatic insect orders Limnology

26

Aquatic insect orders

Limnology

27

Life cycles of aquatic Insects

Holometabolous

4

Egg > > > Adult

caddisflies and

Holometabolous Hemimetabolous

Limnology

28

Holometabolous life cycle

Complete metamorphosis in the caddisfly

Hydropsyche sp.

Larva

Pupa

Adult

Limnology

29

Life cycles of aquatic Insects

Hemimetabolous

3

Egg > Immature (nymph) > Adult

stoneflies, mayflies

Limnology

30

Hemimetabolous life cycle

Limnology

31

Life cycle length

Multivoltine – several generations per year

Univoltine – one generation per year

Semivoltine – one generation every 2-3 years

Baetis

sp.,

univoltine

semivoltine

(Allan, 1995).

Limnology

32

Ecological roles Macroinvertebrates food webs

Macroinvertebrate 4

Shredder POM > FPOM

Scraper diatoms > FPOM

Collector gatherer filterer FPOM

Predators

gatherer filterer

Scraper

Limnology

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General organic matter pathway Limnology

34

Sources of organic matter Autochthonous – instream

diatoms; algae; submerged, floating, and emergent macrophytes

Allochthonous – out of stream

, , dissolved organic compounds, dead organisms

Limnology

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Types of organic matter

Dissolved organic matter

Particulate organic matter

Coarse particulate organic matter

> 1

mm

Fine particulate organic matter

, invertebrate

< 1 mm

Limnology

36

Instream organic matter processing

, macroinvertebrates,

,

Limnology

37

Shredders

Dominant food

Coarse particulate organic material (CPOM)

Feeding mechanisms

Herbivores –

Detritivores – CPOM

Representatives

Scathophagidae (dung flies)

Tipulidae (crane flies)

Macroinvertebrate functional roles in organic

matter processing

A caddisfly of the

family Limnephilidae

Limnology

38

Collectors

Dominant food

Decompose fine particulate organic matter (FPOM)

Feeding mechanisms

Filterers - Detritivores

Gatherers - Detritivores

Representatives

Filterers

Hydropsychidae

Simulidae (black flies)

Gatherers

Elmidae (riffle beetles)

Chironomini

Baetis

Ephemerella

Hexagenia

Macroinvertebrate functional roles

A blackfly of the

family Simulidae

Elmidae

Hexagenia

Ephemerella

Limnology

39

Scrapers

Dominant food

Periphyton (attached algae)

periphyton

Feeding mechanisms

Representatives

Helicopsychidae

Psephenidae (water pennies)

Thaumaleidae (solitary midges)

Glossosoma

Heptagenia

Macroinvertebrate functional roles

A dipteran of the

family Thaumaleidae

Helicopsychidae

Heptagenia

Limnology

40

Predators

Dominant food

Feeding mechanisms

Engulfers –

Piercers –

Representatives

Engulfers

Anisoptera (dragonflies)

Acroneuria

Corydalus (hellgrammites)

Piercers

Veliidae (water striders)

Corixidae (water boatmen)

Tabanidae (deerflies & horseflies)

Macroinvertebrate functional roles

Anisoptera

Corixidae

Limnology

41

Other macroinvertebrates Limnology

42

Low concentrations in

winter and fall and at

high flow

High concentrations in

summer and at low flow

Seasonal variation in particulate organic carbon

Limnology

43

( ):

(25%)

(50%)

CO2

(25%)

Fate of organic matter Limnology

44

debris dams, beaver dams, floodplains,

Storage of organic matter

Limnology

45

Net primary production versus litter fall

Stream Autotochthonous Allochthonous

Bear Brook, NH 0.6 g C/m2/year 251 g C/m2/year

Silver Springs, FL 981 g C/m2/year 54 g C/m2/year

Limnology

46

Carbon fluxes in a stream ecosystem

autotochthonous allochthonous

macroinvertebrate

Limnology

47

The River Continuum Concept

( )

( )

Limnology

48

The River Continuum Concept

Limnology

49

Stream order and the RCC

Low order streams

Coarse particulate

matter (CPOM)

Limnology

50

Mid-order streams

CPOM

periphyton

CPOM

FPOM

Stream order and the RCC

Limnology

51

High order streams

macrophytes

macrophytes

Stream order and the RCC Limnology

52