Primary productivity and chlorophyll a in Prydz Bay and its mouth in Antarctica during the austral summer of 1999/2000

The investigation of phytoplankton standing stock, euphotic layer and photosynthesis rate were carried out in 19 - 27 of January, 2000 at three longitudinal sections (70°30＇E, 73°00＇E and 75°30＇E). The results showed that the high value of chlorophyll a concentration was in inshore bay, polynya and the continental slope of the investigated sea area. At various investigated stations, average chlorophyll a concentration at sub-surface layer (25 m) was higher than that at surface layer; its concentration at the deeper layers of over 50 m decreased with increasing depth. At anchor station, the maximum chlorophyll az concentration appeared at surface layer in Antarctic summer's afternoon while the minimum value appeared in the morning; chlorophyll a concentration at water layer of 0 - 25 m was obviously higher than that at deep water layer, being related to the releasing of ice-algae. High productivity was in inshore bay and polynya of continental shelf. Chlorophyll a concentration at surface layer is closely correlated to the dissolved oxygen concentration in seawater. The sea ares with chlorophyll a concentration of over 1.0ag/dms may be the convergence of CO2 and that of below 1.0 μg/dms may be the source of CO2.