The distribution and abundance of copepods in relation to the physical structure of the Gulf Stream

Abstract

The horizontal and vertical distributions of selected copepod species across the Gulf Stream in September 1982 were investigated along a transect east of Cape Hatteras where the Stream turns offshore. Copepod species distributions across the Stream, and the extent of their diel migrations, can be grouped into several distinct patterns associated with different environmental habitats within the Stream, some of which change depth across the Stream along sloping isopycnals. Copepod behavior, such as probable temperature and depth preferences and diel vertical migration, interacts with the complex physical structure of the Stream to determine at what depths in the water column a species is found at different cross-stream locations. The different environmental habitats are also characterized by different current velocities and directions, and therefore the species groups experience different degrees of downstream and cross-stream transport. Direct cross-stream transport, in addition to mesoscale events such as ring formation, is a likely mechanism connecting some populations of Slope Water and Sargasso Sea zooplankton.