Toxic effects and stress in oysters relation to pollution

Toxic effects of contaminants on oysters have been found to be a serious problem in earlier years with the most serious effects causing collapse of oyster farms in many countries in Europe. For example, during the 1980s, several oyster culture operations were adversely affected with high levels of the marine antifoulanttributyltin (TBT) reported in tissues. A relationship between cause and effect has been established between TBT contamination and reductions in meat weight and increased shell thickness and distortions in the Pacific oyster, Crassostrea gigas. Transplanted juvenile and adult oysters are currently being used to monitor the toxic effects of TBT and many other contaminants in coastal waters. As well as this, many environmental and physiological factors have been found to affect the uptake of contaminants in oysters. Some ecophysiological tests have been reported to demonstrate the relationship between reproductive status, scope for growth and effects of stress temperature on physiological functions of the animal. This chapter aims to complete a review of toxic effects and stress accounts in oysters and to discuss some important links between all causes of concern.