Biochemical composition of Antarctic zooplankton from the Indian Ocean sector

Abstract

Zooplankton samples were analysed for faunal composition, organic carbon, protein, carbohydrate and lipid content. Total zooplankton biomass (as displacement volume) varied from 0.032 to 0.500 ml.m sup(-3) (x = 0.23 + or - 0.14) in upper 200 m with significant difference between the Antarctic and the sub-Antarctic waters. Calanoid copepods were numerically the predominant group comprising greater than 80% of total counts, whereas, euphausiid Euphausia superba was abundant in samples collected south of lat. 55 degrees S. Organic carbon concentrations ranged from 0.83 to 13.04 mgC.m sup(-3) (x = 5.91 + or - 3.59). Lipid was the principal biochemical component, varying between 11.08 to 27.65% (x = 21.04 + or - 4.39). Protein content showed large variations and ranged between 8.02 and 29.9% (x = 19.57 + or - 6.25). Values for carbohydrate content varied from 11.01 to 27.65% (x = 19.62 + or - 4.80). Higher accumulation of lipids in Antarctic zooplankton during phytoplankton blooms (austral summer) could be an adaptative phenomenon, and may function as metabolic reserve and insulation layer