Life of a River - Biology
Aquatic habitats (pg 1 of 2)

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Several life forms spend most, if not all, of their lives in rivers and streams. These aquatic organisms include types of bacteria, algae, plants, zooplankton, crayfish, insects, mussels, fish, amphibians, reptiles, and mammals.

The diversity of aquatic organisms depends on the variety of stream habitats. A sinuous stream provides more habitats than a straight channel. A streambed composed of rocks and sediment of many sizes provides a greater assortment of habitats than a streambed of uniform sediment. Pristine streams can exhibit astounding diversity. An inventory of a small stream in Germany revealed more than 1,300 species in a 1.2-mile stretch.

Critical niches for amphibians and reptiles are provided by different stream and river habitats. River backwaters and sluggish reaches of streams are especially important to frogs and turtles for reproduction and overwintering. Sand and gravel bars provide crucial nesting and basking sites for many turtle species, such as map and softshell turtles. Spiny softshell turtles spend their lives in rivers and streams, leaving only to lay their eggs (PARC, 2002). Mudpuppies, which are the only hosts for the salamander mussel, spend their entire lives within streams, foraging by night and hiding under rocks and ledges by day with the mussel colony they help perpetuate.

Woody material, such as fallen trees in the water and logs along the bank, provide beneficial structure. They become an integral part of the channel, deflecting current, forming scour holes, and providing substrate for attaching organisms, basking sites for reptiles and amphibians, and overhead cover for others.