OCCURRENCE OF AN ALGAL BLOOM UNDER ARCTIC PACK

Summer melting of sea ice leads to the formation of under-ice melt pon ds in Arctic seas. The biological characteristics oi such a pond were studied in summer 1993. The chlorophyte Pyramimonas sp. (Prasinophycea e) formed a unialgal bloom with cell densities of 19.1 x 10(3) cells m l(-1) and a pigment concentration of 29.6 mg m(-3). A comparison with ice core data revealed differences in algal biomass and community stru cture. Physical data indicate that under-ice ponds are a common featur e in the Arctic Ocean. Thus, communities within under-ice ponds, which have not been included in production estimates, may significantly con tribute to the Arctic marine food web.