Intakes as Sampling Locations for Investigating Long-Term Trends in Zooplankton Populations

Abstract

We present data demonstrating the representativeness of a power plant intake as a sampling location for investigating long-term trends in zooplankton populations. The intake (Donald C. Cook Nuclear Plant) and the inshore region (southeastern Lake Michigan) were sampled within a matter of days on 54 occasions between April 1975 and November 1981. Intake population estimates were significantly correlated with inshore region population estimates for all 26 zooplankton taxa categories analyzed. Differences in abundances in intake and inshore region samples were not significant for most euplanktonic taxa. The plant apparently entrained water and microcrustaceans from the sediment–water interface. However, because vertically hauled plankton nets do not effectively sample the lower 1 m of the water column, intake sampling may provide a more accurate representation of nearshore region copepod and cladoceran community structure than traditionally employed methods for inshore region sampling.