VERTICAL PARTICLE-FLUX ON THE SHELF OFF NORTHERN SPITSBERGEN, NORWAY

Suspended and sedimented particulate matter was examined along transec ts on the continental shelf off northern Spitsbergen, Norway, during s ummer 1991. The transects were situated in non-ice-covered areas domin ated by Atlantic water, areas with multi-year ice and the marginal ice zone. The variability of the sedimented. matter with regard to compos ition, quantity and quality between the 7 investigated stations was co nsiderable. The open Atlantic water showed the highest suspended bioma ss [100 to 280 mg particulate organic carbon (POC) m(-3)] and the vert ical 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-y ear ice was low (<65 mg POC m(-3)), the vertical flux was relatively h igh (18 to to 76 mg POC m(-2) d(-1)) and dominated by terrestrial orga nic 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 vert ical flux in the marginal ice zone was higher (5.6% of POC), consistin g mainly of Chaetoceros socialis and Fragilariopsis sp., but a conside rable amount of faecal matter also settled. At all stations zooplankto n strongly influenced the vertical flux, not only by faecal pellet pro duction but probably also by direct mediation of fluxes (e.g. copropha gy).