Phytoplankton biomass and species composition were studied in transects through the ice edge region of the Greeland Sea from 19 July to 8 August 1984. Biomass was estimated by vertical in situ chlorophyll fluorescence and pigment extraction of discrete samples. Preserved material was used for identification of phytoplankton species and calculation of their relative abundances. The results suggest that the various geographical regions of the Greenland Sea differ considerably in their phytoplankton development. Autotrophic biomass and species composition were closely associated with the extent of the annual and seasonal ice cover, hydrographic conditions, nutrient availability and the water masses typical of the different domains. In the NE Greenland polynya a deep mixed layer inhibited the development of a phytoplankton bloom, whereas greatest biomass concentrations were associated with a receding ice edge on the E Greenland Shelf. In the Fram Strait, the position of the relatively stationary ice edge is controlled by frontal dynamics, currents and wind. Due to rapidly changing physical and chemical conditions, phytoplankton biomass showed great variability between stations. High chlorophyll a concentrations may develop locally where melting ice causes stratification or can result from passive accumulation in eddies. In July/August 84 the Fram Strait area was dominated by a typical summer population of flagellates and large diatom species. |
