cholinesterase activity evaluation in capoeta capoeta gracilis as biomarker of enviromental monitoring in gorgan-roud basin

biomarkers are assigned as early warning systems regarding aquatic organisms exposed to pollutants. among which, however, measurement of esterase enzymes activity specially cholinesterase of fish tissues, is a marker for exposure to organophosphate pesticide and carbamates, and this biomarker has been used widely in broad range of investigations. a number of capoeta capoeta gracilis (:cyprinidae) samples were caught from five determined stations located in gorgan river basin, followed by sampling from three distinct tissues including liver, muscle and brain. special activity and inhibition percentage of both esterase enzyme and acethyle cholinesterase (elman method) were also measured. according to our current results, significant differences were detected between enzyme levels of tree tissues of five stations. the maximum value of inhibition percentage of esterase enzymes of three tissues including liver, muscle and brain were calculated as 38.75, 31.01 and 10.62, respectively, when data of downstream of gorgan river at summer were taken into account. hence, due to more inhibition as compared with the other enzyme tissues, we strongly propose the utilization of liver acetyle cholinesterase activity in this species as a biomarker regarding determination and classification of lotic water ecosystems pollution. furthermore, muscle tissue, because of the presence of butyryl cholinesterase (measured in general esterase assay) which is commonly accompanied by more sensivity versus inhibitors, can be used consequently in environmental monitorings. as the last point of view, the study of such reliable markers in diverse seasons showed that the environmental monitoring programs can be more helpful as long as such investigations are carried out in warm seasons in one hand, and based on agronomical calendar plus spraying farms on the other.