Effect Of Metal Pollutants on Hemocytes of Freshwater Molluscs, Bellamya bengalensis: The Reliable Markers of Aquatic Pollution

AbstractHemocytes are useful tool for assessing the toxicity of heavy metals on freshwater gastropods. Freshwater molluscs Bellamya bengalensis were exposed to sodium arsenite (NaAsO2), mercury (II) chloride (HgCl2), lead nitrate, zinc sulphate and copper sulphate (CuSO4.5H2O) for the different exposure periods as 24hrs, 48hrs, 72hrs and 96hrs. Control specimens were untreated by any toxic metals. Hemolymph was collected and hemocytes were stained by Giemsa, Leishmans Eosin Methylene blue solution, neutral red and trypan blue. Results showed that heavy metal toxicity affected the morphology and function of chief immune effector cells (hemocytes) in freshwater molluscs and also inhibited the degree of hemocyte aggregation, clot formation which may affect “encapsulation response”, microaggregation and wound healing. Cells showed neutral red (NR) positive reaction in cytoplasm indicating damage of lysosomal membrane due to metal toxicity. Mortality index was also significantly increased in 96hrs of treated group. This supports the idea that hemocyte analysis is a reliable tool to obtain information about pollution which may act as markers of aquatic biomonitoring approach.KeywordsHemocytes, Aggregation, Freshwater gastropods, Environmental pollution