Two important aspects of stream habitats to consider

1
Two important aspects of stream habitats to
consider

• Stream order (elevation, position in watershed)
• Pool vs. riffle habitat

2
Stream Order
3
Important things that change with stream order

• Slope
• Flow
• Sediment type
• Chemistry (O2, N)
• Temperature
• Light
• Detritus

Organisms
4
Stream continuum conceptVannote et al. 1980
5
Stream continuum conceptVannote et al. 1980
nutrients detritus
light
FPOM/CPOM
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Functional vs. taxonomic groupings of stream
invertebrates

• Functional
• shredders
• collectors
• scrapers/grazers
• predators

• Taxonomic
• mollusks
• crustaceans
• insects
• plecoptera
• trichoptera
• ephemeroptera
• odonata
• diptera
• coleoptera

7
detrital food web
Processing chain commensalism
autotrohic food web
8
Biofilm and nutrient spiraling
9
Biofilm

• periphyton
• bacteria
• fungi
• detritus
• Responsible for nutrient spiralling

flow
10
Primary producers in streams
Mid Order periphyton
High Order flowering plants
Low Order
Bryophytes (moss)
Cladophora (chlorophyte)
Vallisneria
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Detritus- the other base of stream food webs
12
Mollusks
Gastropods
Limpet
Bivalves
13
Isopods, amphipods, decapods (Crustacea)
14
Stoneflies (plecoptera) 1800 species
Adult
Larva
15
Caddisflies (trichoptera) 10,000 species
16
Mayflies (ephemeroptera) 2000 species
17
Dragonflies and Damselflies (odonata) 5,500
species
Dragonflies
Damselflies
18
True flies (Diptera)
Simuliids (black flies) (1,650 species)
Chironomids (midges) (20,000 species)
Tipulidae (craneflies) (15,000 species)
19
Beetles (Coleoptera) 3000 aquatic species
20
True bugs (Hemiptera) 3,300 aquatic species
21
Vertebrates
22
Functional vs. taxonomic groupings of stream
invertebrates

• Functional
• shredders
• collectors
• grazers
• predators

• Taxonomic
• mollusks (collectors, grazers)
• crustaceans (shredders, collectors)
• insects
• Plecopterans (all of above, often important
  predators)
• Trichopterans (all of above)
• Ephemeropterans (grazers, collectors)
• Odonates (predators)
• Dipterans (predators)
• Coleopterans (all of above)
• Hemipterans (predators)

23
How do pools form?

• Pools form by scour

dead zone
scour high flow
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How are pools and riffles different?

• Pools
• low flow velocity
• deep
• finer sediments
• can have low O2
• less swimming required
• less drifting food
• refuge from terrestrial predators
• more fish predators

• Riffles
• fast water
• shallow
• big sediments
• can have higher O2
• have to swim fast
• more food passing by
• more terrestrial predators
• less fish predators

25
How does removing logs affect stream
habitat?Fausch and Northcote 1992 Canadian J. of
Fisheries and Aquatic Sciences 49682
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Intensive logging can have different effects- log
dams
27
Stream insects as indicators of water qualityRoy
et al. 2003 Freshwater Biology

• EPT Index
• ephemeroptera plecoptera trichoptera

chironomids
28
How does canopy cover affect stream insects?
29
Effects of trees on streams

• make pools, change shape
• shade, limit light

Effects of fish on streams

• trophic cascades
• import nutrients from ocean (anadromous)

30
Hubbard Brook experimentLikens et al. 1970
Ecological Monographs 40 23
Removing trees increases erosion and ion,
nutrient input in streams
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Higher in-stream productivity takes up some of
the slackBernhardt et al. 2003 PNAS
Before a storm knocked down all the trees
After the storm
Downstream/upstream

• A lot of the NO3 doesnt make it downstream due
  to uptake by periphyton
• Loss of trees increases primary productivity in
  the stream

32
Trees affect fish, how do salmon affect
trees?Helfield and Naiman 2001 Ecology
33
A positive feedback between trees and salmon?

• Big logs increase pool volume, feed detritivores,
  increase fish production
• Big fish returns import nutrients, enhance tree
  growth

34
Bug exchange between Japanese streams and
forestsNakano and Murakami 2001 PNAS 98 166-170
What are birds eating?
What are fish eating?
35
Bug exchange between Japanese streams and
forestsNakano and Murakami 2001 PNAS 98 166-170
36
Do trophic cascades occur in streams?Power 1990
Science 250 811
37
How does flooding affect insects and
salmon?Wootton et al. 1996 Science 2731558
38
Responses of stream insects to fish
predatorsPeckarsky et al. 2001 Ecology 81240
fish fishless
39
Bioturbation- scum eating fishTaylor et al. 2006
Science 313 833
40
Fish keep things moving along Taylor et al. 2006
Science 313 833
- no fish
- fish
41
Facilitation among stream predatorsSoluk and
Collins 1988 Oikos 52 96
42
Facilitation among stream insectsCardinale et
al. 2006 Nature
43
Facilitation among stream insects Cardinale et
al. 2006 Nature
44
Drift Paradox- how do insects maintain
populations that are always moving
downstream?MacNeal et al. 2004 Freshwater
Biology 49 1260
45
Drift Paradox- how do insects maintain
populations that are always moving downstream?
Juveniles drift downstream
Adults fly upstream