Freshwater Fishes Freshwater communities Temperate Streams Temperate Lakes and Reservoirs Tropical Streams and Lakes.

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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pera

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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