Effects of an organic pollutant (tributyltin) on genetic structure in the pacific oyster Crassostrea gigas

Within the overall context of coastal ecosystem monitoring, the effects of an organic pollutant (i.e. tributyltin) on the genetic structure of the Pac ific oyster Crassostrea gigas along Brittany (France) coasts were studied i n order to identify specific genetic indicators. Contamination experiments were conducted using two concentrations of tributyltin (TBT). Electrophoret ic analyses focused on sis enzyme loci and the results were analysed to dis cern allozyme differences between samples. The survival curves obtained cle arly reveal the high toxicity of TBT on adult oysters. Electrophoretic data also highlighted the existence of allozymes which can be used as putative genetic indicators of TBT contamination. It would appear that the following enzyme systems, aspartate-amino-transferase (Aat-2), adenylate kinase (Ak) and phosphoglucomutase (Pgm) are involved in the main physiological proces ses affected by tributyltin; allozymes of these loci are characterized by f requencies which vary significantly between TBT-resistant and more TBT-sens itive adults. These data reflect the adaptive nature of certain allozymes a nd show that relatively simple methods associated with an appropriate biolo gical material may be a powerful tool to assess the effects of pollutants o n marine invertebrates. (C) 1999 Elsevier Science Ltd. All rights reserved.