Influence of Different Calcium Levels and Low pH of Water on the Plasma Electrolyte Regulation of a Fresh Water Teleost Fish Cyprinus carpio Var. communies, (Linnaeus, 1958)

The present study investigated low pH with calcium and without calcium treatment on gill histology and ionoregulation of fish, Cyprinus carpio exposed to low pH 4.0 with low (normal water) calcium 6 mg/L and low pH 4.0 with added calcium 15 mg/L treatment for a period of 96 h. The light microscopic studies of the processed low pH with low calcium treatment, exposed gills showed marked histological alterations. The lesions of the gills included hypertrophy of the filament and lamellar cells; hyperplasia of the filament and lamellar cells, and deformities of gill arches, filaments and lamellae were seen. But in low pH with high calcium treatment the gill lesins were minimum such as, hypertrophy, hyperplasia and proliferation of chloride cells. In low pH with (normal water) low calcium treatment, plasma ionic levels (Na, K Cl) decreased as the exposure period extended. In all the three experiments sodium level showing steep decrease ranging from 0.405, 21.382 to 8.411 at the end of 24 h to 32.965, 57.350 and 18.915 at the end of 96 h, respectively. Low pH with high calcium treatment, the fish exhibited only a minor depression in the plasma ionic levels showing minimum decrease of 4.952, 20.128 and 7.702 at the end of 96 h, respectively. Impact on gills and ionoregulation were minimum in low pH with added calcium level due to the ameliorative effects of calcium. The significant alteration in both the histology and electrolyte levels can serve as a biomarker of pollutant exposure and effects.