Production of organic matter In Antarctic sea Shelf

Abstract

Particulate organic matter (POM) collected from 3 discrete depths (0, 10 and 30 m) at a single station in the waters off the ice shelf of Princess Astrid Coast (70-degrees-S-11-degrees-E), Antarctica during austral summer, winter and spring of 1986 was analysed for phytoplankton biomass (as chl a), particulate organic carbon (POC) and constituent fractions. Chlorophyll a varied from 0.026 to 3.1-mu-g l-1. POC ranged from 0.280 to 1850-mu-g l-1, particulate carbohydrate (PCHO) from 8 to 193-mu-g l-1, particulate protein (PP) from 16 to 200-mu-g l-1 and particulate lipids (PL) from 8 to 209-mu-g l-1. Large variations during summer signified patchy distribution. Phytoplankton population in 30 m deep water column during winter was dominated by unicellular blue green algal forms while during spring, diatoms such as Thalassiothrix longissima, Thalssiosira sp. were dominant. Sea-ice microalgal communities showed dominance of diatoms whereas dinoflagellates were poorly represented. The cell count varied from 0.15 to 142 x 10(4) cells l-1 with lowest counts during winter. In the zooplankton communities copepods were dominant in all months averaging 24.985%. The maximum zooplankton density of 2280 per 100 m3 was observed in December. Significant correlation was observed between POC and chl a and PL at 10 m depth. Variation in POC was due to variation in community structure, composition and production of the sea-ice algae and phytoplankton in the water column during different months.