ANNUAL CYCLE OF TINTINNIDS IN ADMIRALTY BAY WITH AN EMPHASIS ON SEASONAL VARIABILITY IN CYMATOCYLIS-AFFINIS CONVALLARIA LORICA MORPHOLOGY

In water samples collected from the middle of Admiralty Bay (King Geor ge Island 62-degrees-08'S 58-degrees-25'W) between February 1990 and J anuary 1991, 17 Tintinnina species were noted. Total Tintinnina number s in summer were very high (up to 5000 cells m-3) , but species divers ity was low, consisting mainly of Cymatocylis affinis/convallaria, for ma convallaria. During austral winter, cell numbers were very low, but species composition was diverse. Cymatocylis affinis/convallaria, for ma affinis, and C.affinis/convallaria, forma convallaria, the polymorp hic forms of one species C.affinis/convallaria, appear to be interchan geable during the year. The transition from one form to the other occu rs in the spring and autumn. The typical Tintinnina polymorphism can b e attributed to the prevailing environmental conditions.