Date of Award


Document Type


Degree Name

Master of Science



First Advisor

Dr. John W. Bishop

Second Advisor

Dr. William S. Woolcott

Third Advisor

Dr. Thomas R. Platt


Populations of zooplankton, Keratella cochlea's (Rotifera) Bosmina longirostris (Cladocera), and Mesocyclopsedax (Copepoda) were sampled in Westhampton Lake from June 30 to December 22, 1978. Population densities were estimated over time and analyzed for stability relative to the occurrence of rainfall. Two aspects of stability were used for analysis and given operational definitions as follows: Resistance - a population was resistant if its density was not more variable during periods of rain compared with periods of little or no rain; Persistence - a population was persistent if its density during periods of rain was not different from its density in periods of little or no rain. In the summer, K. cochlearis showed low resistance and non-per­sistence; B. longirostris showed high resistance and persistence; M. edax showed high resistance and non-persistence. In the fall, all three populations showed high resistance and persistence relative to the occurrence of rainfall. Resistance of populations in summer was consistent with the opportunistic, r-selected life history strategy of the rotifer, the more K-selected strategy of the copepod and the intermediate, compromising strategy of the cladoceran. Persistence in the summer was also consistent with these strategies for the rotifer and cladoceran, but not for the copepod. In the fall, the effects of rainfall were masked by the effects of fall turnover in the lake.

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