Modeling salinity drop in estuarine areas under extreme precipitation events within a context of climate change: Effect on bivalve mortality in Galician Rías Baixas

• Published in: The Science of the total environment Vol. 790; p. 148147
• Main Authors: Des, M., Fernández-Nóvoa, D., deCastro, M., Gómez-Gesteira, J.L., Sousa, M.C., Gómez-Gesteira, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.10.2021
• Subjects: Bivalve mortality; Climate change; Ecological modeling; Extreme precipitation events; Hydrodynamic modeling; Hydrologic modeling; Climate change; Ecological modeling; Hydrologic modeling; Extreme precipitation events; Hydrodynamic modeling; Bivalve mortality
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.148147

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 analyzed within a context of climate change. The Rías Baixas (NW Iberian Peninsula) were selected as a representative 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 hydrodynamic model and simulations were performed in order to calculate transport conditions in the Rías Baixas. Salinity data were analyzed to estimate the mortality of the species due to salinity drops. In general, future conditions of moderate and severe mortality may be worse than historically observed, being more intense and covering larger areas. This is mainly observed under neap tides due to less dilution of freshwater plumes when compared with spring tides. Although all the Rías 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, especially 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. [Display omitted] •Climate change impacts on extreme precipitations and river runoff.•Increase of extreme river discharges may lead to higher salinity drops in estuarine areas.•Effect of salinity drops on the mortality of bivalves near river mouths.•Bivalves' mortality increases when extreme river runoff and neap tides match.•The physiography of the estuary is crucial to determine the death rate.