ACUTE TOXICITY BIOASSAY OF CADMIUM ON THE FRESHWATER CATFISH, HETEROPNEUSTES FOSSILIS (BLOCH) AND ASSOCIATED HISTOLOGICAL ALTERATIONS IN GILLSN. JAYAKUMAR, T. FRANCIS, P. JAWAHAR, C.B.T. RAJAGOPALSAMY, R. SANTHAKUMAR AND A. SUBBURAJ
The natural aquatic ecosystem is extensively contaminated with heavy metals that are released from domestic, industrial and several other anthropogenic activities. The persistence and ubiquitous nature of these heavy metals and their tendency to accumulate in organisms affect the organism at tissue / cellular level which in turn affects the normal physiological processes in animals especially fishes. In the present study, the adult freshwater stinging catfish, Heteropneustes fossilis were exposed to five different acute concentrations of Cadmium like 18.45, 36.9, 73.7, 147.4 and 294.8 mg/L Cd for 96 hrs. The 96 hr LC50 of Cadmium for H. fossilis was determined to be 44.13 mg/L. In addition, the study aimed to investigate the histopathological impacts of acute concentrations of Cadmium in the gills. The most common histopathological alterations in the gills of fish exposed to cadmium were characterized by epithelial lifting, vacuolation, blood congestion, lamellar fusion, secondary lamellar damage, hyperplasia and lamellar disorganization. Ultimately, the study revealed that the degree of distortion of the gill was in proportion to the duration of exposure and concentration, i.e., dose and time dependent.
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