Zooplankton ecology in Kavaratti atoll, Lakshadweep, India

Variations in physico-chemical parameters, zooplankton abundance, their distribution, seasonal and diurnal variations in Kavaratti atoll, Lakshadweep were studied for two years. The range of variation in water temperature was 27. 0-31.8°C, pH 7.1-8.4, diss. 02 2.2-7.5 ml/1 and salinity 33.0-35.3 ppt. with the lowest values during monsoon. Day time zooplankton density was low (63- 1,987 no./m3) while it was high at night (1,404-5,762 no./m3). Density varied betwen stations and over seasons. Substratum appeared to control the day time density of drifting zooplankton. Density was the lowest during monsoon in day time samples (202-359 no./m3) while it was the highest in night samples (4,275 no./m3) especially during the monsoon. Fish eggs and larvae (16-32.1 %) and copepods (16.8-26.7 %) dominated in the day time samples, while decapod larvae (26.8 %) and ostracods (20.6 %) dominated in the night samples, zooplankton density was the maximum between 2100 and 0300 hrs and density showed no definite relation with tide. The lagoon appeared to hold its own zooplankton, which is distinct in character and response to physico-chemical parameters