Preliminary Study of Major Zooplankton's Abundance in Polluted and Non Polluted Locations of Vavuniya Tank and Ariyakulam Pond.

Abstract

The influence of pollution effects on the abundance of major zooplanktons like Rotifera, Cladocera and Copepoda were investigated at polluted and non polluted locations of two different fresh water bodies; Vavuniya tank (in between 8°45'13.75-59.23" latitude and 80°30'7.50-53.21" longitude) in the Vavuniya District and Ariyakulam pond (in between 9°40'3.09-7.98" latitude and 80° 1'6.77-10.47" longitude) in the Jaffna District was chosen; the polluted and non polluted locations were identified by measuring the BOD,; during the period from December 2010 to February 2011. The Vavuniya tank (0.6 km²) is perennial and more productive by means of its inland capture fisheries and irrigation, while Ariyakulam (0.015 km²) is ephemeral and not used for fisheries or irrigation. Water samples were collected in the littoral zones. As these locations are densely packed with vegetations, sieve-set (50μm) were used to filter the water samples, preserved with 10% Ethanol and taken to the laboratory for qualitative and quantitative analysis, under the low-power of light microscope. Sedgewick-Rafter cell was used to estimate the zooplankton abundance as individuals/m³. The zooplankton community structure in the non polluted locations of both water bodies were Rotifera > Cladocerans > Copepods. Vavuniya tank leads the Ariyakulum in the entire zooplankton community structure. Especially the abundance of Rotifer was significantly higher (p<0.05) in Vavuniya tank than Ariyakulam. Comparison of the Rotifera abundance within the Vavuniya tank, indicates that it was significantly higher (p<0.05) abundance in non polluted location than polluted location. The second largest abundance goes to Cladocera in the non polluted locations of both water bodies where Vavuniya tank (11786±7116) leads the Ariyakulam (4683±1933). On the contrary, Ariyakulam (4418+517) leads the Vavuniya tank (1904±1833) in both polluted locations. The abundance of Copepods was significantly (p<0.05) higher in the polluted location of the Vavuniya tank, when compared to the polluted location of the Ariyakulam. As it was a preliminary study, the future studies needed to investigate the influence of other biotic and abiotic factors on the zooplankton community structure and abundance in water bodies.