River Ecosystems & Animals

A river ecosystem includes such elements as the flowing water; the river bed and shoreline; the air above them; and various forms of life. Animals are important members of an ecosystem. They benefit from it and contribute to its well-being.

Food and Shelter

• A river ecosystem provides a home for such animals as freshwater fish, frogs, salamanders, turtles and even an occasional dolphin. Various insects live in rivers, such as the water strider and the mayfly larva. A healthy river ecosystem has a food chain that provides food for all, with such plankton as diatoms and heliozoans on the bottom and ducks and otters farther up. Such animals as the mink occasionally come to fish, and deer come to drink.

Contribution of Animals

• Animals promote the health of river ecosystems. Beaver dams provide a haven for plants and animals that prefer quiet waters rather than a rushing stream. Manatees sometimes clean up a river that is clogged with aquatic weeds.

Effects of Change

• Changes can upset a river ecosystem. For example, the loss of fish species through extinction will upset the rhythm of the ecosystem, according to the National Academy of Sciences. Pollution is a change especially deleterious to animals. If pollutants such as DDT or mercury enter a river, not only resident animals will be affected, but also all animals that prey on them either directly or indirectly.