Zooplankton distribution in neuston and water column along west coast of India from Goa to Gujarat

Abstract

Zooplankton distribution and abundance in neuston layer and water column at 4 transects between Goa to Gujarat during January-February, 1988 were studied. The ambient water temperature, salinity and dissolved oxygen at surface layer ranged between 26.3 degrees and 27.3 degrees C, 35.7 and 36.2 x 10(-3) and 4.3 and 4.5 ml.l(-1) respectively. The temperature and dissolved oxygen values decreased with depth. Their values at 200 m depth were 18.2 degrees C and 0.27 ml.l(-1). Zooplankton biomass (ml.m(-3)) and population density (no.m(-3)) were higher in the water column (av=0.5, 592) than in the upper neustonic layer (av=0.3, 245). Copepods were dominant (51.8 to 71.6%). The other important groups were ostracods, invertebrate larvae, chaetognaths, amphipods, pteropods, fish eggs and fish larvae. Sixtyone species of pelagic copepods were identified. Copepod species of genera Nannocalanus, Eucalanus, Clausocalanus and Canthocalanus were abundant both in the upper and lower neuston layers and water column. Significant correlation(P>0.05) was obtained among species of first 2 genera. The species richness and eveness were inversely related to the zooplankton biomass.