Effect of Urea, an Agrochemical on the Histology of Black Clam, Villorita cyprinoides

Abstract

The indiscriminate use of agrochemicals results in run off contamination of water bodies and it adversely affects the aquatic flora and fauna in many ways. Urea is a nitrogenous fertilizer, widely used in agriculture. Toxicological studies were conducted to assess the extent of urea stress on the black clam, Villorita cyprinoides. Bivalves are filter feeders and can accumulate toxins in their soft tissues which form the edible portion of the animal. These pollutants cause cellular and tissue alterations, irregular reproductive patterns and also produce variety of lesions. In the present study, clams were collected from Vembanad Lake, Kerala, India and exposed to different concentrations of urea. Histology of Villorita cyprinoides was assessed after exposing the clams to sub-lethal concentration of urea, which is 0.7 g l-1, for about 14 days along with a control. For histopathological studies, different tissues of clam viz., foot, mantle and gill were excised, processed and stained in haematoxylin and eosin stain. In the experiment conducted, an acute histological response of the tissues to urea was observed in the exposed organisms. The results of the study show that the clams were affected by urea exposure and that it had caused severe damage to various organs.