Response of multiple biomarkers in Cirrhinus mrigala during short term exposure to Chromium

Abstract

Metals are natural components present in the earth’s crust. Among metals chromium is the sixth most abundant heavy metal and is an essential microelement for living organisms. Due to their extensive use in stainless steel manufacturing, leather tanning, wood treatment, etc., it reaches to aquatic ecosystem and affects the aquatic organisms. Fish are the most susceptible species to metal toxicity. Exposure to metals may lead to several toxic effects in aquatic animals, including tissue damage, respiratory changes, alterations of biochemical and physiological mechanisms, and ultimately mortality. In this study, the short term chromium toxicity on plasma ionoregulation (Na⁺, K⁺and Cl^-), biochemical alterations like plasma glucose and protein and gill Na⁺/K⁺-ATPase activity of fresh water fish, Cirrhinus mrigala were investigated. The 96 h LC 50 of sodium dichromate was determined to be 19.00 mg/L. In the present investigation, 1/10^th of the 96 h LC50 value (1.9) (Treatment I) and 1/5 of 96h LC50 (3.8 ppm) (Treatment II) were taken to assess sodium dichromate toxicity. In Treatment I plasma sodium, potassium (except 24^th h), chloride, protein levels and gill Na⁺/K⁺-ATPase activity were decreased and glucose levels of fish Cirrhinus mrigala was increased significantly. In Treatment II plasma sodium, chloride, protein levels and gill Na⁺/K⁺-ATPase activity were decreased, whereas potassium (except 96^th h) and glucose levels were increased significantly of fish Cirrhinus mrigala. From the above responses it was concluded that, the short term chromium toxicity severely affects the above parameters which may be used as potential biomarkers of chromium toxicity to the freshwater fish in the field of environmental biomonitoring.