Dynamics and Community Structure of Zooplankton in the Davis Strait and Northern Labrador Sea

Abstract

The dynamics and community structure of zooplankton in the Davis Strait and the northern Labrador Sea were studied over an annual cycle (23 April 1977 - 16 May 1978). Biological spring, defined as the time of year which includes the annual phytoplankton increase and subsequent increases in zooplankton abundance, proceeds in a counterclockwise sense around the region. It is first observed in April near the southern Greenland coast, from where it proceeds north in the Davis Strait, then moves southward in the Baffin Current and along the retreating ice edge before reaching the Hudson Strait in September and October. Recurrent group analysis was used to identify communities of zooplankton in the region. Distributions of these groups were closely related to the hydrography. The West Greenland Drift is characterized by abundant populations of Calanus finmarchicus , C. hyperboreus , Oithona similis , Conchoecia obtusata , Metridia longa and Microcalanus pygmaeus. The colder, less saline water of the Baffin Current and the Hudson Strait arctic outflow are characterized by populations of Calanus glacialis and the early developmental stages of Pseudocalanus minutus. The breeding cycles of the three species of Calanus tend to be separated both spatially and temporally. Key words: Davis Strait, Labrador Sea, Zooplankton, Zoogeography, arctic, recurrent group analysis, Calanus