IMPORTANCE OF ADVECTION FOR PELAGIC-BENTHIC COUPLING IN NORTH NORWEGIAN FJORDS

Suspended biomass in the upper layer and sedimentation of organic matt er were measured during spring and early summer simultaneously in Bals fjord and Malangen, northern Norway (ca 70 degrees N) in 1992 at four different depths ranging from 30 to 170 m and 330 m, respectively. The bloom took place in almost unstratified waters in April and was domin ated by diatoms and Phaeocystis pouchetii, HARIOT. The biomass of the early bloom was exported from the fjord due to advection, resulting in low sedimentation rates in the fiord. Several advective episodes were observed during the course of the bloom. These were caused by large s cale variation in the wind field along the coast. The bloom continued until the end of April with high POC fluxes ranging from 300-1120 mg m (-2) day(-1) at all depths. Suspended POC in the upper 36 m was high, varied between 16 and 31 g m(-2) day(-1) and was not correlated to the phytoplankton bloom. It is suggested that topographical controlled do wn-fjord wind stress during periods of low stratification gives rise t o extensive water circulation and resuspension, in particular in narro w fiords. Advection of zooplankton into the fjords influences the vert ical flux by introduction and removal of specific zooplankton stocks. The results imply that advection is a significant process for the deve lopment and fate of vernal blooms in north Norwegian fjords and that v ernal blooms and pelagic-benthic coupling will be subjected to interan nual variation due to variable meteorological forcing.