Influence of lunar cycle and hydrological parameters on the depth-wise distribution of zooplankton in the inshore waters off Tuticorin, Gulf of Mannar

Abstract

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.

Diversity and distribution pattern of copepods in Palk Bay coastal waters of India

“…The high salinity observed during April and May and low was during September and October. The salinity values recorded in the present study was similar to the studies conducted by Asha and Diwakar [19] who registered the salinity in the range of (31.2 to 37.6 ‰) in Gulf of Mannar coastal water. The low salinity was during the northeast monsoon (September-November) may be due to the influence of monsoon.…”

“…In all the stations the lowest temperature was recorded between October and December and highest in the month of April, May and June. The similar type of water temperature ranges was reported in earlier observations [2,19,20] in Gulf of Mannar and Palk Bay region.…”

Seasonal Variations in Physico-Chemical Parameters of Manakudy Estuary, Southwest Coast of India

“…The high value of nitrite was recorded station II and low in station IV (Table 1). "The maximum value was recorded during monsoon season may be due to various reason including variation in phytoplankton release, decomposition of ammonia and decrease of nitrate and by recycling of nitrogen and bacterial decomposition of planktonic detritus present in the environment" [14]. The low value recorded during premonsoon in all station could be attributed to the phytoplankton growth [19] in Thengapattanam estuary.…”

“…The salinity was maximum during the premonsoon season and minimum was during the monsoon season (Table 2). "The recorded maximum values could be attributed to the low amount of rainfall, higher rate of evaporation and also due to neritic water dominance" [12][13][14]. "During the monsoon season, the rainfall and the freshwater inflow from the land in turn moderately reduced the salinity" [15].…”