| Summary: | Determination of the biomass of phytoplankton and their associated micrograzers along the 49°W meridian in the Scotia-Weddell Sea sector of the Southern Ocean was carried out at several times during the austral spring 1988-1989. The data reveal a peak of algal biomass moving southward and located at a constant distance of about half a degree of latitude from the ice edge. Microzooplankton biomass closely follows that of phytoplankton.Photosynthesis, growth, excretion and respiration were determined from experiments combining tracer technology and biochemical fractionation. The kinetics of the processes and their control by available light and temperature has been established. On the basis of these data, a mathematical model was developed for calculating daily integrated growth of phytoplankton from the knowledge of light regime, temperature and vertical structure of the water column.Coupling of this model with a one-dimensional hydrodynamical model, calculating the depth of the wind mixed layer from meteorological data and ice cover, allowed simulation of the dynamics of phytoplankton development during the ice-retreat period in this sector of the Scotia Sea-Weddell Sea area.
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