The Effect of Climate Variability on the Abundance of the Sandy Beach Clam (Mesodesma mactroides) in the Southwestern Atlantic

The yellow clam Mesodesma mactroides is a fast-growing, short-lived species that inhabits sandy beaches of the southwestern Atlantic Ocean (SAO). The purpose of this study was to relate interannual fluctuations of the yellow clam population in Uruguay to climate circulation anomalies in the SAO. Twenty-three years of clam abundance, as well as sea-surface temperature anomalies (SSTA), salinity, and wind stress anomalies (WSA) from oceanic reanalyses were used. Composites and linear regressions showed that the best scenario for high abundance of M. mactroides is characterized by cold and salty waters and onshore WSA on the Uruguayan Atlantic coast. These local WSA are part of a cyclonic configuration of WSA in the SAO that forces negative SSTA in the region. High and low M. mactroides abundance tended to occur along with La Nina and El Nifio events in the equatorial Pacific Ocean, respectively. These results suggest that interannual fluctuations in M. mactroides abundance are not only locally but also remotely controlled by regional-and global-scale climate variability modes.