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Article: Rivers and Streams
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- Biology
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CopyrightCOPYRIGHT 2002 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Rivers and Streams
On the continents, aquatic
ecosystems
are of two kinds: lotic ecosystems, in which the water is free-flowing (streams and rivers), and lentic ecosystems, in which the water is relatively stationary. The scientists who specialize in aquatic ecosystems are limnologists.
Physical Features
The limiting factors that govern what organisms can live in lotic ecosystems include current, light intensity, temperature,
pH
, dissolved oxygen, salinity, and nutrient availability
—
variables routinely measured by limnologists to develop a profile of the environment. These conditions differ greatly between small headwater streams and the mouths of such great rivers such as ...