Tidal and seasonal variations in zooplankton of Pullavazhi brackishwater, southeast coast of India

Abstract

Distribution and biomass of zooplankton in relation to tides and seasons were studied in 2 stations (mouth of the estuary and backwaters). The tidal study revealed that the peak values in density (723700 and 1036500 ind.m-3) and dry weight biomass (667 and 738 mg.m-3) were during night high tides in both the stations. Species diversity values were generally high in both mouth and tidal zone and the maxima were 5.3 and 4.5 respectively. In both the stations, summer season registered higher values of density (263000 and 297000 ind.m-3) and biomass (498 and 455 mg.m-3) of zooplankton. Compared to other Indian estuaries, this brackishwater showed abundance of microzooplankton particularly copepod larvae and molluscan veligers which contributed a larger share (average 56 and 58%) to the dry weight biomass.