Vertical Distributions of Continental Shelf Zooplankton in Stratified and Isothermal Waters

Abstract

AbstractFine-scale vertical zooplankton distributions were compared in October 1978 on a cross-shelf transect south of Long Island, New York, at a time-series station south of Long Island, and at a time-series station on Georges Bank. Samples were collected at 5 to 10-m depth intervals with a pumping system and fine mesh (102 μm) nets. The waters south of Long Island were strongly stratified, whereas those of Georges Bank were isothermal. Juvenile or adult copepods accounted for a mean of 91% of the total number of animals collected. Of these, one species (Oithona similis) was overwhelmingly dominant, accounting for a mean of 50% of the total number of zooplankters collected. Comparison of our values for the abundance of O. similis with those obtained with coarser meshes of nets in previous investigations in these waters during the same season suggest that these previous studies may have underestimated the abundance of O. similis by at least a factor of 20.Vertical distributions of some of the same domina...