Population Dynamics of Limnetic Cladocera in a Beaver Pond

In a small, shallow, predation free beaver pond near Georgian Bay, Ontario Ceriodaphnia quadrangula was monacmic and Daphnia ambigua and Bosmina longirostris triacmic. Each species peaked and declined rapidly, presumably overshooting the carrying capacity of a food limited environment. Embryonic development times of each species at different temperatures was determined in the laboratory and fitted with Bĕlahrádek’s function. Calculated instantaneous rates of birth and death were normal for D. ambigua and C. quadrangula but too low to account for the rapid fluctuations in numbers of B. longirostris, suggesting occasional gross sampling errors. Bosmina longirostris may periodically abandon the limnoplankton for a benthic existence thus avoiding capture.