Vertical particle flux on the shelf off northern Spitsbergen, Norway

Suspended and sedimented particulate matter was examined along transects on the continental shelf off northern Spitsbergen, Norway, during summer 1991. The transects were situated in non-ice-covered areas dominated by Atlantic water, areas with multi-year ice and the marginal ice zone. The variability of the sedimented. matter with regard to composition, quantity and quality between the 7 investigated stations was considerable. The open Atlantic water showed the highest suspended biomass [100 to 280 mg particulate organic carbon (POC) m(-3)] and the vertical flux was moderate (24 to 30 mg POC m(-2) d(-1)) and dominated by faecal matter. While the suspended biomass in areas covered by multi-year ice was low (<65 mg POC m(-3)), the vertical flux was relatively high (18 to to 76 mg POC m(-2) d(-1)) and dominated by terrestrial organic and faecal matter. The contribution of phytoplankton cells to the vertical flux of POC, was small in areas covered by multi-year ice, on average about 1%. The contribution of phytoplankton cells to the vertical flux in the marginal ice zone was higher (5.6% of POC), consisting mainly of Chaetoceros socialis and Fragilariopsis sp., but a considerable amount of faecal matter also settled. At all stations zooplankton strongly influenced the vertical flux, not only by faecal pellet production but probably also by direct mediation of fluxes (e.g. coprophagy).