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 George Island 62°08'S 58°25'W) between February1990 and January 1991, 17 Tintinnina species were noted. TotalTintinnina numbers in summer were very high (up to 5000 cellsm^–3), but species diversity was low, consisting mainlyof Cymatocylis affnislconvallaria, forma convallaria. Duringaustral winter, cell numbers were very low, but species compositionwas diverse. Cymatocylis affnislconvallaria, forma affinis,and C.affmis/convallaria, forma convallaria, the polymorphicforms of one species C.affinis/convallaria, appear to be interchangeableduring the year. The transition from one form to the other occursin the spring and autumn. The typical Tintinnina polymorphismcan be attributed to the prevailing environmental conditions.