Other vertebrates

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Other vertebrates
Phylum Chordata   7 Classes Chondrichthyes --
sharks Agnatha jawless fish
(lampreys) Osteichthyes bony
fish Amphibia Reptilia Aves Mammalia    

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• Amphibians
• Salamanders -- predators
• Streams
• Hellbenders, Desmognathus -- fish with legs
• Lakes
• Tiger salamanders breed in temporary pools
• Newts

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• Amphibians (cont.)
• Frogs and toads immatures aquatic scrapers,
  adults terrestrial predators but often feed on
  adult aquatic insects

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2. Reptiles Water snakes Turtles Crocodiles and
alligators Mostly predators except some turtles
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• Birds 11 orders with representatives that are
  closely associated with freshwater
• Egrets, Herons waders, predators (3)
• Gulls, pelicans predators (1)
• Ducks, geese predators, grazers (1)
• geese feed terrestrially, defecate in water
  add nutrients
• Cormorants, anhengas divers, predators (2)
• Eagles, ospreys, kingfishers predators (1)
• Spoonbills, flamingos filter feeders,
  zooplankton (2)
• Sandpipers -- invertebrates (2)

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4. Mammals Bears piscivores sometimes Beavers
Ecosystem engineers 60-400 Million in NA
before Europeans Almost extinct, 6-12 million
today Convert streams ?lakes Feed
terrestrially Moose grazers Hippos terrestrial
grazers Coons predators Otters, mink
predators Platypus invertebrates Manatees
feed on aquatic plants
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Fish-invertebrate interactionsFish are very
efficient at catching zooplanktonAdaptations of
zooplankton1. Big and spiny2. Transparent3.
Hide4. Small
(Werner and Hall 1976)
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• Big and spiny
• Many rotifers are spiny
• Cyclomorphosis seasonal change of form
• Fish are less efficient eating spiny critters

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2. Transparent   Most zooplankton are
transparent e.g., Chaoborus   
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• Hide
• Vertical migration -- hide in the dark depths
• Mysis relicta

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• Small
• Hrbácek -- Czechoslovakian, first demonstrated
  effect of fish on zooplankton size distribution
  in early 60s.
• Ponds stocked with fish small cladocerans,
  rotifers.
• Fish removed large cladocerans, few rotifers.
• Brooks and Dodsen 1965
• Crystal Lake, Conn., fishless
• Alewife introduced
• Average size of zooplankton went from 0.8 ?0.3 mm

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Fish absent large zooplankton outcompete
smaller zooplankton Fish present
selectively feed on larger zooplankton
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More to the story The size of zooplankton affects
algae Hrbácek Fish present small zooplankton,
bloom of algae, low water transparency Fish
absent large zooplankton, few algae, pond
clear Fish make the pond eutrophic!
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And it gets more complicated What about
piscivorous fish?
zooplankton
phytoplankton
small fish
Biomass
Piscivores
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Carpenter and Kitchell Cascading trophic levels
top-down regulation (bottom-up regulation
nutrient limitation) Experiment in three lakes
in Wisconsin Peter, Paul, and Tuesday lakes
Predaceous fish
Primary production
Small fish
Zooplankton
Algae
Nutrients
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Peter and Paul bass present, few minnows, lots
of zooplankton, and little chla Tuesday no
bass (winter kills), lots of minnows, few
zooplankton, high chla
Experiment Paul reference Peter removed bass
(most), added minnows Tuesday added bass,
removed minnows
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• Results
• Tuesday added bass, removed minnows
• Result about as expected
• Big increase in zooplankton
• Big decrease in algae (chla)
• Results somewhat complicated by Chaoborus
• Peter removed (most) bass, added minnows
• Results not quite as neat
• A few zooplankton increased because the few
  remaining bass kept the minnows at the edge of
  the lake
• Well-fed bass spawned, young bass ate
  zooplankton, algae increased

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Fish can have a major role in lakes. What about
streams?
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Power and Mathews Stream in Oklahoma Algae ?
stoneroller ? bass Stoneroller Campostoma,
Cyprinid In summer the stream becomes a series
of pools. Pools with bass lots of algae Pools
without bass little algae
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David Allan Electro-shocked a reach of stream in
Colorado and removed trout every summer for 4
years. No effect on macroinvertebrates. Why?
Trout are drift feeders Drift is excess
production?
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Experiments 1. Split-pool One side with
stonerollers, one side without. Big difference
in algae 2. Added bass Algal height increased,
especially in center of pool
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Fish can be important regulators in streams Fish
are important components of many freshwater
ecosystems