Comparative account of accumulation of heavy metals and structural alterations in scales of five fish species from Harike Wetland, India

Harike wetland is a wetland of international importance (Ramsar site). It is a source of numerous direct and indirect values like water for drinking and irrigation, habitat for natural flora and fauna, fishing and navigation. From last three decades this fragile aquatic ecosystem receives continuous waste water discharge from agricultural, sewage and industrial sources including heavy metals, hence, the purpose of this study was to investigate the presence and percentage of heavy metal (Cu, Zn, Pb, Ni, Cd, Cr, Fe, and Al) in the scales of five fish species (Labeo rohita, Catla catla, Cirrhinus mrigala, Labeo calbasu and Cyprinus carpio) of Harike wetland employing energy dispersive X-ray microanalysis (EDX) technique. The result has shown the most common heavy metals detected in Harike wetland are cadmium (Cd), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), Zinc (Zn), Iron (Fe) and Aluminum (Al). The occurrence of these metals is different in different fish species. Some other pollutants like Carbon (C), Sulphur (S) and Silicon (Si) were also detected in scales. Various abnormalities have been identified in the scale structure due to alteration of elemental composition like dislocation and uprooting of lepidonts from their point of attachment to circuli, broken and disorganized circuli and hole-like depression formed by uprooted lepidonts.