Phytoplankton composition and cell carbon distribution in Prydz Bay, Antarctica: relation to organic particulate matter and its {delta}13C values

In January-February 1991, in Prydz Bay, phytoplankton bloomwas evident in the inner shelf area with the dominant diatomsbeing represented mainly by pennate species of the Nitzschia-Fragilariopsisgroup. Dinoflagellates and naked flagellates were most abundantin the centre of the bay; however, larger heterotrophic speciesprevailed at the southern stations. Cell carbon values (average317 µg l^–1; range 92-1048 µg l^–1) foundin the bloom in the south were chiefly due to pennate diatomsand larger heterotrophic dinoflagellates. Much lower carbonvalues (average 51 µg l^–1; range 7-147 µgl^–1) in the outer shelf region were mainly contributedby large centric diatoms (70-110 mu;m) and small dinoflagellates(5-25 µm). Wide ranges of algal cell sizes were observedin both southern and northern communities; the overlapping ofsizes of diatoms and flagellates, the latter containing heterotrophs,suggested complex trophic relationships within the planktonand an enhanced heterotrophic activity in the south. North-to-southvariations in surface