The main purpose of this project is to estimate the river contribution to mercury pollution in the most important ecosystems of the Ebro Delta: rice paddies and coastal areas. We aim to determine i) the role of the rice paddies in mercury methylation, bioavailability and mercury transfer to land, and ii) disentangle both, the river contribution ('anthropogenic' mercury) and that of marine mercury ('natural' mercury) to the high levels observed in seabirds from this area. We expect that this research proposal allow to estimate the importance of flooded rice paddies sediments for mercury bioavailability, its transfer along the local food chains and, ultimately, the exportation to the surrounding terrestrial habitats. Mercury data gathered from rice analysis will allow to estimate associated risks to rice consumption and, if adequate, to estimate maximum daily intake. The joint studies on mercury contamination, trophic ecology and activity patterns of seabirds (terns and Audouin's gulls) will allow to elucidate the influence of diet and foraging area on observed mercury levels. Moreover, in the Audouin's gull we expect to establish the relationship between female mercury burden, and that in the eggs and chicks and to evaluate potential mercury effects on the reproductive success. We hope that the development of new methodologies, as such of mercury stable isotopes, will help to stablish the 'source apportionment' from different mercury origins (river /sea) to explain the high levels found in breeding seabirds from the Ebro Delta.
Project Leader: Sergi Díez (equipo investigación CSIC); Coordinador: C.Sanpera & L.Jover (UB)