CS39B Zooplankton - Community Dynamics
Date: Wednesday, June 12, 2002
Time: 12:00:00 PM
Location: Sidney
MalkinSY, University of Waterloo, Waterloo, Canada, smalkin@sciborg.uwaterloo.ca
Taylor, W, D, University of Waterloo, Waterloo, Canada, wdtaylor@sciborg.uwaterloo.ca
Fish can exert a large influence on the structure and composition of lake plankton communities. Five fishless lakes in Algonquin Park, Ontario, were sampled 6 times from June to September, 2000 and 2001. The zooplankton communities in these lakes varied from diverse to very simple. In all lakes, crustacean zooplankton biomass was dominated by calanoid copepods, with increasing relative importance of cladoceran biomass with increasing pH. Cyclopoid copepods did not make a substantial contribution to crustacean zooplankton biomass in any of the fishless lakes. Contrary to our working hypothesis that zooplankton communities in fishless lakes would be dominated by large individuals, the size-spectrum of zooplankton was variable. This survey was complemented by a comparative investigation of two morphometrically similar, oligotrophic, clearwater, moderately acidic lakes: one that supported planktivorous fish and one that was fishless. The prediction that at similar levels of total phosphorus the fishless lake would have a lower chlorophyll concentration was not supported. Yet, as expected, in the fishless lake a greater proportion of phytoplankton biomass was in larger size-fractions, suggesting zooplankton grazing was directed at different phytoplankton sizes.