CoAuthors

Laura A. Ruiz Etcheverry (Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias de la Atmósfera y los Océanos (DCAO). Buenos Aires, Argentina. CONICET – Universidad de Buenos Aires. Centro de Investigaciones del Mar y la Atmósfera (CIMA). , Argentina); Martin Saraceno (Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias de la Atmósfera y los Océanos (DCAO). Buenos Aires, Argentina. CONICET – Universidad de Buenos Aires. Centro de Investigaciones del Mar y la Atmósfera (CIMA). , Argentina); Baptiste Picard (Centre d’Etudes Biologiques de Chizé, UMR 7372, CNRS-La Rochelle Université, 79360 Villiers en Bois, France); Christophe Guinet (Centre d’Etudes Biologiques de Chizé, UMR 7372, CNRS-La Rochelle Université, 79360 Villiers en Bois, France)

In situ data obtained from CTD (Conductivity, Temperature, and Depth) sensors attached on 5 elephant seals (Mirounga Leonina) that crossed the Argentine Continental Shelf (ACS) between the 17th and 31st of October 2019 are analyzed. The analysis of the temperature and salinity along the trajectories allowed us to identify two different regions: north and south of 42°S. In the north-ern region, the temperature is 1°C warmer and 0.5 saltier than in the southern region. Sub-surface (15 m depth) in situ data collected correlates very well (r=0.9) with satellite sea surface tempera-ture (SST) data. The SST pattern observed suggests that north of 42°S warm waters are coming from the San Matias Gulf (SMG). Temperature-Salinity (TS) diagrams allowed to clearly identify Malvinas Water, Low Salinity Coastal Water, Mid-Shelf Water, and Water with High Salinity Coastal Water from SMG. The latter water mass was observed only in the northern region and the other three were present in both regions. The high spatio-temporal resolution of the in-situ da-ta shows regions with intense gradients along the Temperature (T) and Salinity (S) sections that were associated with a seasonal front that develops north of Peninsula Valdes in winter due to the entrance of cold and fresh water to the SMG. The speed of the elephant seals is correlated with tidal currents in the northern region, in good agreement with a region where a macro tidal regime is observed. Finally, we show that the maximum depth reached by the elephant seals can be used to detect errors in the bathymetry charts.