Procambarus clarkii as a bioindicator of heavy metal pollution sources in the lower Ebro River and Delta

In the Ebro River basin, point and diffuse pollution of heavy metals stems mainly from industry and agriculture. Bioaccumulation patterns were examined under different pollution sources (point and diffuse) using levels of heavy metals (As, Cd, Cr, Cu, Hg, Pb and Zn) in abdominal muscle tissue of Procambarus clarkii. P. clarkii captured under point source effects presented the highest concentrations of Hg, Pb and As; and were related with distance to the source of industrial waste sediments. Mean Hg levels in crayfish exposed to point sources of metals significantly exceeded legal allowed values established by the European Union legislation. In the Ebro Delta, high levels of As, Cr, Cu and Zn were associated with traditional agriculture activity (diffuse pollution) as well. These results demonstrate the potential of P. clarkii to bioaccumulate heavy metals from both point and diffuse sources and hence potentially transfer these metals to higher trophic levels.This study was carried out with the financial support of Spanish Ministry of Environment and the Catalan Water Agency (ACA), Government of Catalonia (MOBITROF project) as well to Ministerio de Educación y Ciencia, research project CGL2006-01487, Plan National I+D+I). We thank Lluís Llornet, David Mateu, Mireia San Lorenzo and Melissa Faria for field and laboratory assistance. Dr. Katherine Sharpe helped to improve the English and provided useful comments on a previous version of the manuscript.Peer reviewe