|
3D - Exposure and effects of environmental contaminants in marine organisms (TUP/179) Immunotoxicity of metals in starfishes: in situ experimental study in a Norwegian fjord. Coteur, Geoffroy1, Gillan, David1, Joly, Guillemette1, Pernet, Philippe1, Maage, Amund2, Dubois, Philippe1, 1 Universite Libre de Bruxelles, Brussels, (Brussels), Belgium2 Alex Stewart Environmental Services A/S, Odda, (Hordaland), Norway ABSTRACT- The accumulation of metals and their effects on the immune system were studied in starfishes (Asterias rubens) from a Norwegian fjord characterised by a steep gradient of metal pollution in the sediments. The concentrations of metals and some immune responses were measured in starfishes from natural populations along the gradient (long-term accumulation) and in starfishes that were transferred up the gradient (short-term accumulation) or down the gradient (depuration). At long-term, Cd and Pb accumulations by starfishes living at normal salinity (30‰) were related to the level of contamination of the environment while Cu and, to a lesser extent, Zn accumulations appeared strictly controlled. At short-term, Pb was accumulated steadily in both the pyloric caeca and the body wall, Cd and Zn were accumulated transiently in the pyloric caeca and Cu was not accumulated at all. It is concluded that Pb is chronically accumulated, without apparent control, Cd is subjected to a regulating mechanism in the pyloric caeca which is overwhelmed at long-term; Zn is tightly controlled in the pyloric caeca and Cu in both pyloric caeca and body wall. Two immune parameters, the concentration of immune cells and the production of reactive oxygen species by these cells, were measured. The immune responses were stimulated in contaminated starfishes from natural populations. However, the sensitivity of these responses towards metals appeared to be strongly modulated by the salinity stress. In starfishes transferred up the contamination gradient, the immune responses were inhibited and closely followed the short-term accumulation of metals in the animal organs. Starfishes transferred down the gradient did not recover normal immune responses in the short-term and appeared highly sensitive to caging stress. It is suggested that the impact of metals on the immune responses of A. rubens in field conditions occurs in three phases. Short-term inhibitory effects are exerted by a direct action of metals on the immune cells and are followed by a recovery due to the induction of protective mechanisms. Eventually, when these mechanisms are overwhelmed by a long-term contamination, indirect and durable stimulatory effects on the immune responses appear due to a global disruption of the animal physiology. Key words: immunotoxicity, metals, fjord, echinoderm |
