Monitoring the Effects of Water Pollution on Cyprinus carpio in Karakaya Dam Lake, Turkey MURAT OZMEN, 1, * ABBAS GU ¨ NGO ¨ RDU ¨ , 1 F. ZEHRA KUCUKBAY 2 AND R. ELIF GU ¨ LER 1 1 Faculty of Arts and Science, Department of Biology, Environmental Toxicology Laboratory, Inonu University, 44069, Malatya, Turkey 2 Faculty of Pharmacy, Department of Analytical Chemistry, Inonu University, 44069, Malatya, Turkey Accepted 9 August 2005/Published online 23 December 2005 Abstract. Karakaya Dam Lake (KDL) is one of the most important water sources, both for irrigation and fishery, located in eastern part of Turkey. This study is concerned with the pollution of the lake contributed by urban, industrial and agricultural activities. The parameters selected for this aim were the enzymes commonly used as biomarkers of environmental pollution. The activity of glutathione S-transferase (GST), carboxylesterase (CE), lactate dehydrogenase (LDH), acid phosphatase (ACP) and aspartate amino transferase (AST) has been determined in liver tissue samples of Cyprinus carpio,a representative species of KDL. Furthermore, brain acetylcholinesterase (AChE) activity which is mainly affected by pesticides such as organophosphates, has been assayed. Chemical analysis results showed that KDL was polluted by various heavy metals as it was apparent from water, sediment and gill tissue. The activity of brain AChE was significantly lower in all localities than Tecimli area (St)5) where there is no agricultural and industrial activities in the immediate periphery. Thus, this change of AChE activity may relate to agricultural pollution in KDL. On the other hand, no significant differences were found for selected enzyme biomarkers, but condition factor (CF) or hepatosomatic index were significantly dif- ferent from the St)5 samples, a result that may be attributed to water pollution in KDL by various contaminants. Keywords: biomonitoring; water pollution; Cyprinus carpio; fish; enzyme activity Introduction The increasing emphasis on the improving the quality of aquatic ecosystems, and monitoring surface waters has highlighted the need to know what factors causes the environmental deterio- ration. Pollution of water sources due to xeno- biotics may play a major role in decline of aquatic animals. Increasing awareness of the adverse effects of anthropogenic activities and pollution on aquatic environment has focused interest on health of fish populations and pos- sibilities to utilize these health parameters for assessment of the quality of aquatic environment (Henry et al., 2004). The potential utility of biomarkers for monitoring both environmental quality and the health of organisms inhabiting polluted ecosystems has received increasing attention during recent years (Lopes et al., 2001; Samecka-Cymerman and Kempers, 2003; Gauthier et al., 2004). *To whom correspondence should be addressed: Tel.: +90-551-905-1570; Fax: +90-422-341-0037; E-mail: mozmen@inonu.edu.tr Ecotoxicology, 15, 157–169, 2006 Ó 2005 Springer Science+Business Media, Inc. Printed in The U.S.A. DOI: 10.1007/s10646-005-0045-1