Elevated planktonic rotifer biomass in acidified metal-contaminated lakes near Sudbury, Ontario

Abstract

The planktonic rotifer biomass and abundance in two trace metal-contaminated, acidified lakes were compared with that of six non-acidic lakes in central Ontario, Canada, which had low levels of metals. Rotifers, especially Keratella taurocephala Myers, were an order of magnitude more abundant in the acidified lakes. They composed 16 to 51% of the total zooplankton biomass in these lakes, but <2% in the non-acidic lakes. Recent experimental work supports a hypothesis that the great abundance of rotifers in the acidic lakes is attributable to a reduction in densities of crustacean competitors.