Modeling Salinity Drop In Estuarine Areas Under Extreme Precipitation Events Within A Context Of Climate Change: Effect On Bivalve Mortality In Galician Rias Baixas

The mortality of infaunal bivalves (Venerupis corrugata, Cerastoderma edule, Ruditapes decussatus and Ruditapes philippinarum) due to a drop in salinity caused by extreme precipitation events in estuarine areas has been ana-lyzed within a context of climate change. The Rias Baixas (NW Iberian Peninsula) were selected as a representa-tive area of the estuarine environments where bivalve gathering is performed. Bivalve mortality under extreme precipitation events was analyzed both for historical (1990-2019) and future (2070-2099) periods. Precipitation data were retrieved from the Coordinated Regional Climate Downscaling Experiment (CORDEX) project under the Representative Concentration Pathway (RCP) 8.5 scenario and were converted into river discharges using the HEC-HMS hydrological model. The calculated river discharges were introduced into the Delft3D hydrody-namic model and simulations were performed in order to calculate transport conditions in the Rias Baixas. Salinity data were analyzed to estimate the mortality of the species due to salinity drops. In general, future con-ditions of moderate and severe mortality may be worse than historically observed, being more intense and cov-ering larger areas. This is mainly observed under neap tides due to less dilution of freshwater plumes when compared with spring tides. Although all the Rias Baixas may be potentially affected, the impact will differ for each ria, being Arousa, where the highest discharges occur, the most affected. The differences among rias, espe-cially those with a similar discharge pattern as Pontevedra and Vigo, suggest that bathymetric features also play a key role in the extent of the area affected by mortality. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).