Spatial distribution and life-cycle timing of zooplankton in the marginal ice zone of the Barents Sea during the summer melt season in 1995

Abstract

The marginal ice zone (MIZ) in the northern Barents Sea is ecologically important because it represents a highly productive area in Arctic water masses north of the Polar Front. During a multi- disciplinary cruise in 1995, ecological and oceanographic processes were investigated at four stations located in a north-south transect in the MIZ. This study was carried out in Arctic water masses north of the Polar Front where ice conditions varied from dense first-year pack ice to open water. Also, the phytoplankton development varied along the transect from a pre-bloom situation at the northern- most station to a post-bloom situation in the open water. This paper includes a study of the zooplank- ton community and population structure of some of the dominant copepod species. Numerically, the most important mesozooplankton components were the copepods Calanus glacialis, Pseudocalanus minutus and Oithona similis. Copepods of Atlantic origin, such as Calanus finmarchicus and Oithona atlantica, gave evidence of an advection of Atlantic water masses into the area. It is concluded that the occurrence of new cohorts of Arctic copepods coincides with the onset of the phytoplankton bloom in the MIZ, and, that therefore, the spawning relies on stored energy.