PELAGIC PROCESSES AND VERTICAL FLUX OF PARTICLES - AN OVERVIEW OF A LONG-TERM COMPARATIVE-STUDY IN THE NORWEGIAN SEA AND GREENLAND SEA

Pelagic processes and their relation to vertical flux have been studie d in the Norwegian and Greenland Seas since 1986. Results of long-term sediment trap deployments and adjoining process studies are presented , and the underlying methodological and conceptional background is dis cussed. Recent extension of these investigations at the Barents Sea co ntinental slope are also presented. With similar conditions of input i rradiation and nutrient conditions, the Norwegian and Greenland Seas e xhibit comparable mean annual rates of new and total production. Major differences can be found between these regions, however, in the hydro graphic conditions constraining primary production and in the composit ion and seasonal development of the plankton. This is reflected in dif ferences in the temporal patterns of vertical particle flux in relatio n to new production in the euphotic zone, the composition of particles exported and in different processes leading to their modification in the mid-water layers. In the Norwegian Sea heavy grazing pressure duri ng early spring retards the accumulation of phytoplankton stocks and t hus a mass sedimentation of diatoms that is often associated with spri ng blooms. This, in conjunction with the further seasonal development of zooplankton populations, serves to delay the annual peak in sedimen tation to summer or autumn. Carbonate sedimentation in the Norwegian S ea, however, is significantly higher than in the Greenland Sea, where physical factors exert a greater control on phytoplankton development and the sedimentation of opal is of greater importance. In addition to these comparative long-term studies a case study has been carried out at the continental slope of the Barents Sea, where an emphasis was la id on the influence of resuspension and across-slope lateral transport with an analysis of suspended and sedimented material.