Research On The Response Of Polymesoda Erosa To The Effects Of SCCPs

Short-chain chlorinated paraffins (SCCPs), a new form of persistent organic pollutants (POPs), are being produced and used extensively. Mangrove clams (Polymesoda erosa) are marine bivalves and can be used as potential indicators to monitor nearshore marine pollution. The study was conducted with multivariate morphometrics to explore the morphological difference between P. erosa and P. expansa for more accurate morphological discrimination of the two clams and by using semi-static test method to test the response of the clams in terms of multiple biomarkers to the effects of SCCPs. The results showed that:(1) Shell width, shell height, ligament length and ligament width of the clams are dominant factors in the discrimination functions established. The comprehensive discrimination rate of stepwise discriminant can be as high as 86.0% at accuracy.(2)NRRT/SOD/MDA/FRAP/AChE/GST/CAT of the clams varied significantly (p <0.05) after exposed to 0.5mg/L SCCPs for 3 days. In general, the biomarkers tended to vary more significantly with the increase of SCCPs concentration after exposed to SCCPs at the concentration between 0.5mg/L and 20mg/L, suggesting a dose effect relationship between them.(3)The biomarkers showed different variation patterns when stressed by SCCPs within 15 days. NRRT in the blood lymphoid tissue of P. erosa kept decreasing. In general, SOD/MDA/CAT/GST/FRAP tended to be varying in rise-decline-rise pattern. SOD/MDA/CAT/FRAP in the gill tissue of P. erosa varied in the trend of induction-inhibition and GST/AChE varied in the trend of up-down-up.(4) The blood lymphoid tissue biomarkers of P. erosa are more sensitive than the gill tissue biomarkers of P. erosa. The sensitivities of the biomarkers to SCCPs were ranked as SOD> MDA> GST> CAT> MDA> FRAP> AChE.(5) When the stresses of SCCPs were removed, the biomarkers of P. erosa could be restored partially but not to original position. The morphometric characteristics of the clam shells can be used to improve the accuracy of morphologically discriminating P. erosa and P. expansa. The responses of P. erosa to SCCPs in NRRT/SOD/MDA/FRAP/AChE/GST/CAT were significant and both dose-effected and time-effected. This study has laid a basis for further study of the ecological toxicology and pollution monitoring of SCCPs.