A study was conduced to assess the depth wise variation and influence of lunar cycle and hydrological parameters on the distribution of zooplankton constituents in Tuticorin inshore waters between April 2011 and March 2012. Fortnightly sampling of zooplankton and hydrological parameters at four different depths like 5 m, 10 m, 15 m and 20 m was carried out on every full moon and new moon day to assess the variation. The zooplankton constituents were found in dominance in the order of copepod> decapod>Lucifer>fish eggs>cladocerans> Alima larvae>chaetognatha at all the depths. The swarming of zooplankton constituents were noticed more towards 15 m depth especially during new moon period. The full moon and new moon variation in the density was statistically significant for bivalve larvae and Lucifer (p<0.05) and the depth wise variation was significant only for decapods (p<0.05). The studies indicated that northeast monsoon which starts during late September in Tuticorin influences the environmental conditions as well as the distribution patterns of the zooplankton constituents in the Tuticorin inshore waters.

Lunar cycle, distribution, zooplankton constituents, Tuticorin