Freshwater Fishes

Freshwater communitiesTemperate StreamsTemperate Lakes and ReservoirsTropical Streams and Lakes

Traditional biotic regions

Temperate streams• Well studied aquatic environments

– Highly accessible, experimental manipulations

• Highly fluctuating environments– Daily, seasonally, interannually

• Very manipulated habitats– Damming, pollution, diversions, channeling,…

Temperate streams – Factors affecting fish distribution

• Physical factors– Temperature– Gradient– Flow regime

• Chemical Factors– Oxygen levels– pH

0

5

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Feb Apr Jun Aug Oct Dec

Riv

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(C

)Farmington River

La Nivelle River

Colorado River Flow

CyprinidaeColorado pikeminowPtychocheilus lucius

Temperate streams – Factors affecting fish distribution

• Biological Factors– Predator-prey interactions– Competitive interactions

• Differential resource exploitation• Aggressive behaviors

• Biogeographic Factors

Lack of refuge from predation

Temperate streams - Zonation

• Mountain zone– Fast flows, Oligotrophic (low productivity), gravel– Salmonidae, Cottidae

• Foothill zone– Intermediate flows and productivity– Salmonidae, Cyprinidae, Catostomidae, Percidae,

Centrarchidae…

• Valley floor zone– Slow flows, Eutrophic (high productivity), soft

sediments– Centrarchidae, Cyprinidae, Ictaluridae,

Clupeidae…

Mountain zone

Temperate Lakes and Reservoirs

• Relatively young environments– A few (reservoirs) to a few thousand (lakes) years+ 1500 reservoirs in the USA

• Few species exclusively adapted to lakes– Exception in very large & old lakes (Great Lakes

and Lake Baikal)

• Manipulated habitats– Exotic species, eutrophication, water level changes,

pollution

Temperate Lakes & Reservoirs – Factors affecting fish distribution

• Physical factors– Temperature

• Cold water lakes (Salmonids)• Warm water lakes (Centrarchids, Percids, Esocids)• Two story lakes with Epilimnion & Hipolimnion

– Light / Turbidity• Productivity and abundance of planktivorous

fishes

– Water level fluctuations• Access to spawning sites

– Substrate

Temperate Lakes & Reservoirs – Factors affecting fish distribution

• Chemical factors– Oxygen levels– pH

• Biological factors– Predation– Competitive interactions

Temperate Lakes & Streams – Zonation. Example: Long lake

(MN)

Lake Malawi• Old lake (2 million years)• 600 x 75 km; 785 m depth• ~550 fish species

– 546 endemic species– 500 Haplochromine chichlids

• Rapid speciation– Simpatric speciation– Microallopatric speciation