UPWELLING-GENERATED PLANKTON STRANDLINES - IMPORTANT PREDICTABLE FOODSOURCES FOR SEABIRDS AT HUSVIK, SOUTH GEORGIA

Sustained strong offshore winds generate upwelling in the fjords of no rthern South Georgia. Deepwater plankton is ''pumped'' by upwelling to wards sandy beaches at the heads of the fjords; calanoid copepods, cha etognaths and pteropods are stranded by the sand ''filter'' in large q uantities on falling tides. Local benthonic species (harpacticoid cope pods and amphipods) are present in the plankton but do not strand. Str andlines are very rich (< 4 kg wet mass m(-2))) and provide large frac tions of the food of kelp gulls, sheathbills and terns in the austral summer. Birds can only exploit fresh strandlines, since air-drying of the plankton soon makes it too salty to eat.