Study on the responses of oxidative stress biomarkers to heavy metals accumulation in the clam Meretrix meretrix along the Beibu Bay

The research was designed to select the biomarkers which can sensitively indicate the heavy metals pollution pressure by evaluating the responses of the seven oxidative stress biomarkers to heavy metals accumulation in native clams Meretrix meretrix along Beibu Bay.In the autumn of 2011,native clams Meretrix meretrix from 6 sampling sites in the intertidal zone was examined.The contents of heavy metals in soft tissue and oxidative stress biomarkers in gill and digestive gland of clams were measured.The distribution characteristics of metals and biomarkers were also analyzed.Based on the analysis,we conducted correlation analysis between biomarkers and the contents of heavy metals.The result showed that there were great differences between heavy metals accumulation and oxidation stress biomarkers responses.Most oxidation stress biomarkers have obvious organizational differences.The contents of SOD,GPx,GST,GSH and GSSG in gill were higher than digestive gland,while CAT activity was higher in digestive gland.For TBARs there were no obvious differences between the two issues.In the environment that contains a variety of heavy metals,GSH/GSSG in gill and Cd in soft tissue have significant correlations.As for the antioxidant enzymes,CAT in gill has significant positive response with Pb,while GST in digestive gland has negative response with As.Besides,TBARs in gill has significant positive correlation with Hg and negative correlation with Cd.In addition,TBARs in digestive glands has negative correlation with Pb.Correlation analysis indicated that several kinds of biomarkers can sensitively indicate the influence of heavy metals on Meretrix meretrix antioxidant defense,therefore could be used as suitable indicators for the assessment of heavy metals contamination pressure of Beibu Bay.