SELECTED ASPECTS OF THE PHYSICAL OCEANOGRAPHY AND PARTICLE FLUXES IN FJORDS OF NORTHERN NORWAY

Results regarding the physical oceanography and the dynamics of partic ulate fluxes in fjords of northern Norway are presented. The phytoplan kton spring bloom takes usually place in April in almost homogeneous w ater and comes to an end before the estuarine circulation starts in la te May/early June when snow and ice melting gives rise to usually one pronounced pulse of freshwater run-off. During late summer and autumn river run-off is usually small and of limited significance for the par ticulate dynamics. Much of the spring bloom material is apt to sink to the bottom, but overwintering herbivores give rise to decreased verti cal losses from the upper layers as well as a tendency towards a decre ased seasonal variability compared to more enclosed coastal systems in boreal fjords of southern Norway. While destruction and mineralisatio n of sedimenting matter is of significance below the euphotic zone, gi ving rise to a decrease in vertical flux, resuspension is of importanc e in the lower water column and close to the rivers. Coastal currents strongly influence the north Norwegian fjords and particulate signals from rivers are small and do not penetrate extensively into the fiords . Advection of particulate matter, phytoplankton and zooplankton along with various water masses in and out of the fjords seems to play an i mportant role for the ecology and particulate fluxes in this area. The rapid exchange of water masses between the coastal currents and even the innermost fjords as well as the comparatively small discharge of f reshwater gives rise to scenarios where particulate fluxes inside the coastal zone are to a large extent determined by external, oceanic for cing. North Norwegian fjords are, therefore, not independent entities, but in various degrees part of the Norwegian Coastal Current.