Biomass and metabolism of zooplankton in the Bransfield Strait (Antarctic Peninsula) during austral spring

Zooplankton biomass (as dry weight), respiration and ammonia excretion were studied in three different size classes (200-500, 500 1000 and > 1000 mu m ) in the Bransfield Strait during December 1991. Average mesozooplankton bi omass was 86.45 +/- 56.74 mg dry weight m(-2). which is in the lower range of the values cited in the literature for polar waters. Higher biomass was observed in the Weddell water. The small size fraction accounted for about 50% of total biomass while the largest one represented 35%. Rather high met abolic rates were found, irrespective of whether the organisms were incubat ed in the presence of food. No significant differences were observed in mas s specific respiration and ammonia excretion rates between different temper atures of incubation (0.2-2.3 degrees C) and between the size classes studi ed. Because of the very low biomass values observed, the metabolic requirem ents of I nesozooplankton during December represented a small fraction of t he primary production.