Seasonal variation of antioxidant and biotransformation enzymes in barnacle, Balanus balanoides, and their relation with polyaromatic hydrocarbons

Seasonal variations in the antioxidant enzymes (catalase, superoxide dismut ase [SOD], NADH-DT diaphorase), biotransformation enzyme, glutathione-S-tra nsferase (GST) and microsomal lipid peloxidation in digestive tissue of bar nacle, Balanus balanoides, from polluted and non-polluted populations have been evaluated. Relationships with accumulated polyaromatic hydrocarbon (PA H) concentration in barnacle tissues and environmental parameters (water te mperature, salinity, dissolved oxygen concentration, water pH) were determi ned. As a general trend, maximum antioxidant enzyme and GST activities were detected in the pre-monsoon period or summer (March-June) followed by a gr adual decrease during the monsoon (July-October) with a minimum in the post -monsoon period or winter (November-February). This pattern was similar to tissue concentrations of PAHs, resulting in a significant positive correlat ion with antioxidant enzymes, mainly catalase and SOD. Microsomal lipid per oxidation exhibited an almost reverse trend of seasonal variation to that o f antioxidant enzyme activities indicating an enhanced susceptibility of ba rnacle tissues to oxidative stress. Among the environmental parameters, onl y water temperature seemed to have a significant effect on observed variati ons of antioxidant enzymes and GST activities. The barnacles from polluted and non-polluted populations exhibited seasonal differences in the activiti es of ail the enzymes studied, particularly catalase, SOD and GST, suggesti ng the possibility of some biochemical adaptation in organisms from a chron ically polluted environment. The results indicated that antioxidant defense components, catalase and SOD, are sensitive parameters that could be usefu l biomarkers for the evaluation of contaminated aquatic ecosystems. The res ults also suggested the potentiality of barnacle, B. balanoides, as a bioin dicator organism against organic pollution. (C) 2001 Elsevier Science Ltd. All rights reserved.