Reconstruction of historical Daphnia communities in damaged lakes from analysis of sediment-stored resting eggs

Atmospheric emissions from the nickel and copper mining and smelting industry in Sudbury have caused extensive damage to many lakes in a large area surrounding the smelters. The cladoceran zooplankton, Daphnia were among the most affected groups of organisms in these damaged lakes. In this study, the ephippial resting eggs of Daphnia, which accumulated in layers of lake sediment, were used to ewe historical changes in the egg bank in 12 Sudbury area lakes and in one additional lake near Dorset, Ontario. Ephippial accumulation rates varied greatly among lakes, but statistical comparisons with lake morphometry, water chemistry, and trophic status variables could not explain the variations in deposition rates. A larger array of lakes or more historical data on the changes in associated biotic communities are probably needed to adequately assess the factors determining the natural ephippial deposition rates in lakes.; New genetic techniques for extracting and amplifying mtDNA from ephippial eggs were used to provide information on historical species composition. (Abstract shortened by UMI.)...