TEMPORAL AND SPATIAL VARIATIONS OF PHYTOPLANKTON FROM BOECKELLA LAKE (HOPE BAY, ANTARCTIC PENINSULA)

The main water body at Hope Bay, Boeckella Lake, was sampled at four s ites for phytoplankton during summer 1991 to assess the influence of n utrients from nearby penguin rookeries on both phytoplankton density a nd composition. The site located at the base of the rookeries had tota l phosphorus values comparable to those reported from the most eutroph ic Antarctic lakes. During the ice-free period most of the Chlorophyce ae and Cyanophyceae recorded were concentrated at this site. Phytoplan kton density increased strongly in the area opposite to the rookeries where ice began to form; an under-ice bloom of Ochromonas aff. ovalis (Chrysophyceae) was observed in this area.