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Changes in the nearshore and offshore zooplankton communities in Lake Ontario: 1981-88

Canadian Journal of Fisheries and Aquatic Sciences

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Abstract

We examined trends and factors influencing changes in nearshore and offshore zooplankton abundance and composition in Lake Ontario between 1981 and 1988. In the nearshore (southshore and eastern basin), zooplankton abundance decreased and shifts occurred in the relative abundances of Bosmina longirostris and Daphnia retrocurva (eastern basin) and Daphnia retrocurva and Daphnia galeata mendotae (southshore). These changes could have resulted from increased vertebrate predation or reduced food resources which intensified the effects of predation. In the offshore, the first appearance (FA) of the larger, less common cladoceran species occurred earlier in the season as of 1985. FA was correlated with cumulative epilimnetic temperature (CET) and the catch per unit effort (CPUE) of alewife (Alosa pseudoharengus) a?Y165 mm caught in U.S. waters in the spring. In 1987, when CET was high and CPUE of alewife a?Y165 mm was low, large populations of these cladocerans developed in June and July. Bythotrephes cederstroemi, a recent invader in the Great Lakes, was abundant only in 1987 when the CPUE of alewife was lowest. Changes in zooplankton abundance, development, and composition along the nearshore-offshore gradient reflected effects of temperature, habitat, and planktivory on the community.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Changes in the nearshore and offshore zooplankton communities in Lake Ontario: 1981-88
Series title:
Canadian Journal of Fisheries and Aquatic Sciences
Volume
48
Issue:
8
Year Published:
1991
Language:
English
Contributing office(s):
Great Lakes Science Center
Description:
p. 1546-1557
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1546
Last page:
1557
Number of Pages:
11