MICROPHYTOBENTHIC SEASONALITY IN NEAR-SHORE MARINE-SEDIMENTS AT SIGNY ISLAND, SOUTH ORKNEY ISLANDS, ANTARCTICA

The seasonal pattern of the microphytobenthic community at a near-shore site on the east coast of Signy Island (60°43′S, 45°38′W), South Orkney Islands, was examined over a period of 18 months. Sediment chlorophyll levels showed distinct seasonal variation linked to the photon flux density reaching the benthos. The microphytobenthic community was able to survive under ice and to respond rapidly to higher light intensities that occurred following the breakout of the sea-ice. Seasonal variation in sediment organic content, even at the peak of the benthic bloom. Low rates of sedimentation of material from the water column during the benthic bloom indicated that the benthic algae were mostly responsible for the increase in sediment chlorophyll concentrations. It is suggested that the benthos may play an important role in seeding the phytoplankton bloom through resuspension. © 1991.