HydroMedit 2014, November 13-15, Volos, Greece 162 BIOCHEMICAL EFFECTS OF ALMIX HERBICIDE IN THREE FRESHWATER TELEOSTEAN FISHES Samanta P. 1 , Pal S. 2 , Mukherjee A.K. 3 , Senapati T. 4 Ghosh A.R. 1 * 1 Ecotoxicology Lab, Department of Environmental Science, The University of Burdwan, Golapbag, Burdwan, West Bengal 713104, India 2 Department of Environmental Science, Aghorekamini Prakashchandra Mahavidyalaya, Subhasnagar, Bengai, Hooghly, West Bengal 712611, India 3 P.G. Department of Conservation Biology, Durgapur Government College, Durgapur,West Bengal 713214, India 4 School of Basic and Applied Sciences, Poornima University, Jaipur, Rajasthan 302022, India Abstract Freshwater teleostean fishes Anabas testudineus, Heteropneustes fossilis and Oreochromis niloticus were exposed to almix (66.67 mg/l) for a period of 30 days to investigate the toxicological responses on acetylcholinesterase (AChE), oxidative and antioxidant enzymes. AChE activity was increased significantly (p< 0.05) in muscle, brain and spinal cord in all test fishes, highest in muscle of H. fossilis but lowest in spinal cord of A. testudineus. Significant increased lipid peroxidation (LPO) level in all tissues was observed after almix intoxication, maximum in liver of O. niloticus and minimum in brain of H. fossilis. Catalase (CAT) activity was increased significantly in all fish tissues after almix exposure while glutathione-S-transferase (GST) showed significant reduced activity in liver, in particular, maximum in liver of H. fossilis. Protein content in all concerned tissues was significantly declined and highest reduction was observed in muscle of A. testudineus while lowest in liver of H. fossilis. So, the present study is able to shed light on the changes in acetylcholinesterase activity, oxidative parameters and antioxidant enzyme profile under long-term exposure of almix and these responses can be used as indicators of herbicidal contamination. Keywords: Almix, Antioxidant enzymes, Teleostean fishes *Corresponding author: Apurba Ratan Ghosh (apurbaghosh2010@gmail.com) 1. Introduction Bioaccumulation and non-biodegradable nature of the pollutants may pose a serious threat to the non-target aquatic organisms and ultimately cause health risk to human beings (Binelli & Provini 2004). These surface water contaminants from industrial processes or agricultural runoff are the major contributors of aquatic system at local, regional, national, even at global levels (Palus et al. 1999; Cerejeira et al. 2003). Almix ® 20WP (a third generation herbicide) attacks and destroys the broad leaf weeds and sedges by stifling the growth of rice crop. It is a combination of 10% metsulfuron methyl, 10% chlorimuron ethyl and 80% adjuvants (Safety Data Sheet 2012). Fishes are recognized as sentinel organisms for ecotoxicological studies because they are continuously exposed to different types of toxic chemicals coming from different anthropogenic sources. They also play a significant role in evaluating the potential risk associated with contamination in aquatic environment (Lakra & Nagpure 2009) and can predict an early detection of aquatic contamination (van der Oost et al. 2003). Fishes possess a defensive mechanism to counteract the impact of oxidative stress posed by environmental contaminants such as herbicides, heavy metals and insecticides. These create imbalance between pro-oxidants and antioxidants ratio, leading to generation of reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 - ) and hydroxyl radical (OH·) which have recently come into focus in the field of ecotoxicology (Facerney et al. 2001; Monteiro et al. 2006). ROS reacts with biological macromolecules at supramolecular levels having gained potency and leads to enzyme inactivation, lipid peroxidation (LPO), DNA damage and even cell death (Peña-Llopis et al. 2003). Catalase, an enzymatic antioxidant, catalyzes H 2 O 2 produced by dismutation of superoxide anions into less toxic water and oxygen molecules (Lushchak et al. 2001). Glutathione-S-transferases, a phase II biotransformation enzyme, catalyze the conjugation of glutathione into a variety of compounds which are involved in transportation and elimination of reactive compounds (Sies 1993). The Lipid peroxidation (LPO) is a secondary LPO product and regarded as an indicator of biochemical toxicity of environmental contaminants (Draper et al. 1993). AChE activity also has been selected as biomarker of pesticidal toxicity in fish by different authors (Moraes et al. 2007) and hence plays a vital role in physiological functioning of fish (Dutta & Arends 2003). Here, three Indian air-breathing food teleosts viz., Anabas testudineus (Bloch), Heteropneustes fossilis (Bloch) and Oreochromis niloticus (Linnaeus) were