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(W/MF170) Enzyme activities as biomarkers of freshwater pollution: responses of fish AChE and Na+, K+ - ATPase. Fernández-Vega, C.1, Sancho, E.1, Ferrando, M.1, Andreu, E.1, 1 ABSTRACT- Thiobencarb, an organocarbamate herbicide, has been widely used in the rice area of the Alfubera Natural park (Valencia, Spain). After sprayed levels of thiobencarb are being detected in the Lake Waters. This area is an historical and common habitat for the European eel, Anguilla anguilla. Indiscriminate use of thiobencarb causes serious metabolic disturbances in aquatic organisms, as tissue damage and stressful condition and alters physiological state hereby changing the biochemical constituents of aquatic organisms. Thiobencarb was also reported as a herbicide which causes neuronal dysfunction in mammals mainly due to the inhibition of both ATPase and AChE activities, both enzymes play strategic roles in the animal physiology. Previous works in our laboratory showed perturbations on the energy reserves of skeletal muscle and liver in the eel as consequence of thiobencarb exposure. The effects of a sublethal thiobencarb concentration (1/620LC50-96hr) on muscle enzyme activities of the European eel and their recovery from intoxication were investigated. Eels from Alfubera Lake were exposed to 0.22mg/L of thiobencarb during 96 hours in a flow-through system and then a recovery period of 8 days in clean water was allowed. Muscle AChE and Na+, K+-ATPase activities were evaluated at several exposure and recovery times. As result, thiobencarb induced significant (p<0.05) inhibitory effects on both enzymatic activities from the first hours of exposure to this herbicide. Inhibitions upon 70% of these enzymatic activities were found at 2 hr of contact with contaminated water. Animals were able to survive in free pesticide-water but most of the enzymatic disorders persisted during the recovery phase. These results indicated that muscle AChE and Na+, K+-ATPase activities would be reliable indicators of exposure to herbicide contaminated-water. Key words: AChE, Na+, K+-ATPase , thiobencarb |
