Evaluation of biomarkers in oyster larvae in natural and polluted conditions

Crassostrea gigas D-shaped larvae were subjected to different conditions of temperature and salinity for 24 h and four biomarkers (acetylcholinesterase (AChE) activity, thiobarbituric acid reactive substances (TBARS) levels, glutathione S-transferase (GST) and catalase (CAT) activities) were measured. AChE activity decreased when salinity increased from 25 to 30 and 35 psu at 20 and 25 degreesC. Temperature did not seem to have an influence on AChE activity. TBARS levels increased as a function of salinity when the temperature was maintained at 20 degreesC, whereas at 25 degreesC no effect of salinity could be observed. Variations in GST and CAT activities were not significant with salinity and temperature except that catalase activity was higher at 25 degreesC than at 20 degreesC. Exposure experiments were conducted at 23 degreesC and 30 psu with carbofuran (100 and 1000 mug/l) and malathion (100 and 300 mug/l). There was an inhibition of AChE activity with carbofuran, and a toxic effect shown by an increase in TBARS levels counteracted by increases in GST and CAT activities which protected the larvae. When two pairs of adults producing larvae were taken into consideration, significant differences in biomarker levels were noted between the larval offspring of each pair. Malathion induced a decrease in AChE activity and an increase in CAT activity. (C) 2004 Elsevier Inc. All rights reserved.