Zooplankton Seasonal Succession in Lake Ontario at Northshore, Midlake, and Southshore Stations in 1982, and a Comparison with 1970

Abstract

The seasonal pattern of zooplankton succession in Lake Ontario was similar at three stations along a north–south transect, with differences attributable to physical factors. Because of warming within the thermal bar zone, the spring succession at the northshore station was early relative to the midlake station, but after stratification the northshore station lagged behind due to frequent upwelling events. Thermal bar formation along the south shore was followed by downwelling throughout the summer, giving a deeper epilimnion. These events may have contributed to not only the greater biomass at this location, but also succession which preceded that at the other stations during summer and fall. The species composition and the timing of the summer succession were very similar to those reported for 1970. Lake Ontario zooplankton did not change markedly in response to changes in nutrient loading and salmonid predators during the 1970's.