Otolith microchemistry interrogation of comparative contamination by Cd, Cu and PCBs of eel and flounder, in a large SW France catchment

Individual European flounder and European eel levels of contamination by cadmium, copper and 7PCBs were related to their retrospective pattern of habitat use, using a combined toxicology and otolith microchemistry approach. The results showed that both species used the freshwater, the upper and lower estuarine habitats. There was a strong difference in the level of contamination of eel compared to flounder, with higher levels of PCBs, copper (Cu) and cadmium (Cd) in eel. The differences of contamination between muscle and liver were also specific to the considered species. The choice of the river habitat at an early age seemed to increase the risk of exposure to PCBs. The results suggested that the use of the upper estuary was related to a higher level of copper for both species and of PCBs for the flounder. The higher level of liver cadmium was measured for fish spending the longer time in the lower estuary. ► We investigated the levels of PCBs, Cu and Cd in flounder and eel in the same estuary. ► We compared changes in the level of contamination related to retrospective habitat use. ► Both species use different estuarine habitats and have different contamination levels. ► Cu and PCBs seemed to be more accumulated in the upper estuary zone. ► Cd accumulation was related to the use of the lower estuary.