Physiological assessment of fish health in mineral-rich areas of Ganjam, Odisha, India, and chronic toxicity of zirconium oxychloride on the fishes of Channa punctata.

Abstract

The high concentration of metal toxicants in aquatic ecosystems has a detrimental impact on fish health that ultimately jeopardizes human health. Such threats mostly arise in mineral-rich areas where an increase in metal concentrations occurs in aquatic bodies due to anthropogenic activities like mining. The present study assessed the health of food fish Channa punctata from the mineral-rich areas of Ganjam, Odisha, India, mined for heavy and transition metal ores like ilmenite, zircon, monazite. The fishes collected from these areas showed histopathological anomalies in vital organs like the liver, kidney, gills, stomach and intestine while cytological analysis revealed vacuolated cytoplasm and micronuclei. Biochemical analysis showed a significantly lower lipid concentration in muscle (i.e., 0.177 ± 0.177mg/gm) and liver (i.e., 0.169 ± 0.002mg/gm) as compared to non-exposed fishes from adjoining non-mineral rich areas having a mean protein concentration of 87.48 ± 8.16 and 77.75 ± 0.892mg/gm tissue in the muscle and liver, respectively, and a mean lipid concentration of 0.29 ± 0.009mg/gm muscle and 0.34 ± 0.009mg/gm liver. Chronic exposure to sublethal concentrations of zirconium oxychloride, a salt of zirconium, resulted in a significant decline in the concentration of protein, ranging from 57.5 ± 0.929 - 63.88 ± 1.95mg/gm in muscle and 45.35 ± 2.332 - 51.98 ± 1.036mg/gm in the liver. The lipid concentrations in muscle (0.03 ± 0.009 - 0.17 ± 0.009mg/gm) and liver (0.06 ± 0.012 - 0.19 ± 0.007mg/gm) were also significantly lower than the non-exposed fishes. Marked degenerative changes were identified in the histological sections of the gill, intestine, stomach, liver and kidney of zirconium oxychloride-treated fishes along with various nuclear deformities and micronucleus.