Coastal systems often serve as sinks for toxic elements, and changes in salinity, pH and temperature, predicted to occur in the next decades due to global climate change, are expected to influence elements geochemistry in aquatic systems. The effects of these changes may also alter biota sensitivity and elements uptake rates. These fluctuations can lead to important changes in estuarine communities, mainly on those organisms living in direct contact with sediments, such as polychaetes. In line with IPCC warnings, Horizon2020 and National strategies (INEI, RIS3-Centro), the present proposal will provide information on how expected variations in pH, salinity and temperature will influence trace elements biogeochemistry and impact economically and ecologically important polychaete species, alone and in combination with elements concentration and availability. This information will help predicting changes that marine systems undergo in the projected climatic scenarios.