Study On The Induction Of EROD Activity In Benthic Fish By Organic Contaminations In Marine Environment

There have been many efforts to find suitable biological parameters for pollution monitoring programmes in the past 20 to 30 years. The monooxygenase (MO)-activity of fish has been shown to be useful as an 'early warning' system for environmental contamination. Ethoxyresorufin-O-deethylase (EROD) is one of the model reactions of the cytochrome P-450-1A1 mediated monooxygenase system. It has been reported that Cytochrome P-450-JA1 is induced in fish by a variety of aquatic pollutants including polycyclic aromatic hydrocarbons (PAH), polychlorinated dibenzodioxins (PCDD) and certain PCB (polychlorobiphenyl). Therefore, measurement of EROD activities that is combined with cytochrome P-450-1 Al isozyme becomes an efficient tool for evaluating fish response to the above contaminants.This paper concerns the induction of EROD activities under various environmental stresses. EROD activity measured by kinetics fluorescence spectrophotometry, was selected as an indicator of PAHs and PCBs effects in benthic fishes. It was indicated that the induction of cytochrome P-450-1A1 was detected in the liver of Fish Paralichthys olivaceus by EROD activity specific for PCBs, and that there existed a dose/effect relationship between EROD activities and specific pollutant concentrations. In the meantime, the optimal conditions for analysis of EROD activity were discussed. Evidence was presented EROD induction was a potential biomarker and feasible indicator to assess the health of seawater. Moreover, an initial assessment of biological effects on Fish Hexagrammos otakii was carried out in well-chosen stations of the coasts along Dalian. It was proved to be feasible that EROD activity was used to assess specific contamination through combined with other analysis data of PCBs. EROD induction in fish liver exposed to organic contamination demonstrated the ability of this technique to be an available and efficient marker of exposure to specific pollutants. The use of EROD parameter to monitor biological effects constitutes a new approach in marine monitoring system because its early-warning function in assessing pollution in marine ecosystems. It has to be noted that factors that have effect on EROD activities in organisms are various. Therefore, a regular biological effects monitoring has been carried out for three years along Changhai area of Dalian by measurement of EROD activities in fish. The optimal conditions including sampling principle, sampling time and measuring method for analysis of EROD activity were further discussed. The results clearly demonstrate the feasibility of studying such parameters in the field and provide the scientific and technical basic for establishment of a marine industrial standard of P.R.China-Determination of EROD Activity with Kinetics Fluorescence Spectrophotometry in Marine Fish. On the basis of above-mentioned work, a much faster and simpler method for the hepatic EROD activities measurement of fish was introduced in this paper, just using a fluorescence plate-reader. The results of this new method are validated against the well-established method using dynamic fluorescence spectrophotometry. The comparison of the new and faster method for measuring the EROD activity using a plate-reader with the conventional method showed better sensitivity and precision. The compactness and rigidity of the equipment and the speed of analysis makes the plate-reader method very suitable for the evaluation of the biological effects of marine pollutant in a large geographical scale.It was summarized that the measurement of EROD activity in fish is quite promising as a means of evaluating environmental pollution. Such an approach can be a highly informative, and cost-effective, complement to the chemical monitoring programme developed in the recent years.