Toxicity Study of Lead Nitrate on Freshwater Fish Cirrhina Mrigala.

Abstract

Chemicals present in the environment tend to alter the physiology of flora and fauna. Heavy metals tend to accumulate in the biosphere by virtue of their non-biodegradable nature. It is known that accumulation of heavy metals in tissues and organs results in cellular and molecular damage in various species (Cestari et al., 2004;Flora et al., 2012). The present study demonstrates the morphological and biochemical effects associated with the accumulation of the heavy metal lead in adult fish, Cirrhina mrigala (Common Indian Carp). Adults of Cirrhina mrigala were exposed to increasing concentrations of lead nitrate for a span of 96 hours, post which anatomical and biochemical changes were monitored. External morphology of adult fish and that of the liver and intestine were also qualitatively examined. The liver of treated fish appeared enlarged and had more mass compared with the control, whereas the intestine showed discolouration indicating ingestion of lead. Enzymes indicating stress and cellular damage were assayed in liver extracts prepared from exposed fish. The enzymes studied were succinate dehydrogenase, alanine transaminase, aspartate transaminase, acid phosphatase and alkaline phosphatase. A significant increase was foundin the activity of all of the enzymes except succinate dehydrogenase probably indicating hepatotoxicity. Succinate dehydrogenase activity was seen to have decreased, possibly indicating oxidative stress. Analysis of the neural marker enzyme acetylcholinesterase in brain extracts from these fish also showed a significant decrease in its activity which could lead to a misregulation in neurotransmission. These results directly reflect on the toxicity caused by accumulation of lead in the adult fish.Copy Right, IJAR, 2016,. All rights reserved.