Abstract:

Eleven species of seven genera of loricate choanoflagellates were found in Great Wall Bay, King George Island, west Antarctica during the sampling period from January 22 to February 8, 1991. Choanoflagellates was an abundant taxa in Great Wall Bay. Their total abundance ranged from 5.1×10 3 to 5.3×10 4cells/l. The spatial distribution of choanoflagellate species and abundance showed heterogeneous patterns. Maximum concentration of chlorophyll a and the highest abundance of choanoflagellates located at the depth of 20m and 30m respectively. Choanoflagellates usually showed a tendency of following the variations of chlorophyll a concentration in their vertical abundance. The regression analysis on the basis of 40 data sets showed that there was a positive correlation between abundance of choanoflagellates and chlorophyll a concentration in this season. The four dominant species of choanoflagellates, Bicosta spinifera,Crinolina aperta, Diaphanoeca multiannulata and Parvicorbicula circularis , distributed widely from surface to bottom in Great Wall Bay.They counted for more than 90% of total choanoflagellates in every layers. B. spinifera was up to about 41% of the mean value of surface abundance of total choanoflagellates. D. multiannulata reached the highest abundance of 2.2×10 4 cells/l at 20m depth on 25 January 1991.