Effects of salinity and temperature on the expression of enzymatic biomarkers in Eurytemora affinis (Calanoida, Copepoda)

In order to establish effective enzymatic biomarkers that could provide in situ early warning of contaminant exposure in estuarine ecosystems, the potential effects of the principal abiotic factors (temperature and salinity) were investigated on common biomarkers, the acetylcholinesterase (ACNE) and the glutathione S-transferase (GST) in Eurytemora affinis. Short term salinity stress effects simulated during an experimental tide indicated that enzymatic activities of this species are characterized by maximum expression related to an optimal salinity range (between 5 and 15 psu). Moreover, longer time exposure to various salinity tanks confirmed the effects of this factor on both ACNE and GST activities. Therefore, optimal ACNE activity was measured at 10 psu, while optimal GST activity was measured at 5 psu. Furthermore, significant effects of temperature were also recorded, particularly for ACNE expression (slight effects were measured on GST expression) with an optimal condition at 11 degrees C. These experiments indicated a more pronounced effect of salinity over temperature especially on the ACNE expression and confirmed the need to standardize sampling procedures in relation with environmental parameters for biomonitoring studies based on enzymatic analyses. (c) 2006 Elsevier Inc. All rights reserved.