Cadmium, lead and mercury accumulation in European eel (Anguilla anguilla) from four Mediterranean wetlands:...

Multiple factors, including pollutants, have contributed to the decline of the European eel (Anguilla anguilla L.1758) in recent decades. Heavy metals are toxic to marine organisms, yet limited data are available on their occurrence in eels in the Mediterranean region. In this context, muscle, kidney, and liver tissues from 118 European eels collected in four wetlands in southeastern Spain were analysed for cadmium (Cd), lead (Pb), and mercury (Hg), and an Individual Mean Bioaccumulation Index (IMBI) was calculated. Mercury was detected in all samples and Pb in all liver samples. The presence of Pb in muscle and kidney, as well as the presence of Cd in all tissues, varied between wetlands. Metal concentrations differed both between wetlands and among tissues (e.g. higher Cd in kidneys and higher Pb in liver), whereas eel developmental stage and weight were not significant factors. Some eels showed muscle metal concentrations above the legal limit. The sampling site was the main factor influencing IMBI values, with renal IMBI being the most informative tissue-specific index, thus turning IMBI into a useful relative indicator of metal bioaccumulation patterns among wetlands. Wetland bioaccumulation profiles differed even within the same geographical region. No clear link was found between chemical pollution and the ecological quality of wetlands, but metal distribution and bioaccumulation patterns indicated chronic exposure. These findings highlight the urgent need to incorporate specific monitoring and pollution control strategies for each wetland into eel management plans.