The effect of diapause emergence on the seasonal dynamics of a zooplanktonassemblage

1. The role of seasonal phenology in the emergence of zooplankton from diap ause in patterns of seasonal abundance in the water column was investigated in Oneida Lake, New York. Replicate emergence traps, placed in contact wit h the lake sediments at two locations (one at a shallow site and one at a d eep site), were monitored between May and August. 2. Although six rotifer taxa showed a clear seasonal succession in the wate r column throughout the study period, all but one taxon emerged exclusively in spring. Three cladoceran and three calanoid copepod species, also prese nt in the water column throughout the study period, again showed predominan tly spring emergence. In contrast, three cyclopoid copepod species had dist inct seasonal periods of emergence that corresponded, at least in part, to the timing of abundance peaks in the plankton. 3. These results for a single lake are largely consistent with patterns obs erved or inferred by other investigators for other lakes: variable dependen ce of abundance in the plankton on diapause emergence for species with long -lived diapausing eggs (i.e. rotifers, cladocerans and calanoid copepods), and much closer dependence for species with short-lived diapausing immature stages (i.e. cyclopoid copepods).