Upland and lowland

Much freshwater fish and invertebrate communities around the world show a pattern of specialization into upland or lowland river habitats.

This in turn produces the other characteristics of an upland river—an incised course, a river bed dominated by bedrock and coarse sediments, a riffle and pool structure and cooler water temperatures.

This in turn produces the other characteristics of a lowland river—a meandering course lacking rapids, a river bed dominated by fine sediments and higher water temperatures.

[5] The generally clear, cool, fast-flowing waters and bedrock and coarse sediment beds of upland rivers encourage fish species with limited temperature tolerances, high oxygen needs, strong swimming ability and specialised reproductive strategies to prevent eggs or larvae being swept away.

[6] The generally more turbid, warm, slow-flowing waters and fine sediment beds of lowland rivers encourage fish species with broad temperature tolerances and greater tolerances to low oxygen levels, and life history and breeding strategies adapted to these and other traits of lowland rivers.

Cascadilla Creek , near Ithaca, New York , in the United States , an example of an upland river habitat
Map of the world showing elevation levels
Amazon River near Manaus , Brazil, an example of a lowland river habitat