Distribution and zoogeography of planktonic crustaceans and dipterans in glaciated eastern North America

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Abstract
Zooplankton samples, usually together with morphometric, physical, and chemical data, were collected from 696 lakes in glaciated eastern North America between 1969 and 1978. Geographical distributions of the 44 Crustacea and 4 Diptera species suggest six broad categories: 23 species appear to have no barriers to dispersal throughout the area; 7 have restricted ranges, possibly because of either recent evolution or competitive exclusion; 3 may be gradually invading the area from centres to the south or west; 1 is a euryhaline estuarine form with a limited freshwater distribution; 4, possibly 5, are found almost exclusively in areas of former glacial lakes or spillways and may be classified as "glacial opportunists"; 9 species have distributions which appear to be linked in some unspecified way to calcium–magnesium water hardness.