Suitable habitat for marine mammals during austral summer in San Jorge Gulf, Argentina

Abstract

espanolEl Golfo San Jorge (GSJ) es una region oceanografica importante debido a la influencia de dos frentes de marea, siendo uno de los sectores mas productivos y con alta biodiversidad marina del Mar Argentino. El objetivo de este estudio fue identificar cuales variables oceanograficas explican la presencia de mamiferos marinos y explorar el solapamiento de la riqueza predicha con las areas frontales del GSJ durante el verano austral. La distribucion potencial de las 9 especies (Balaenoptera sp., Cephalorhynchus commersonii, Globicephala melas, Grampus griseus, Lagenorhynchus australis, L. obscurus, Mirounga leonina, Orcinus orca, Otaria flavescens) fue modelada con Maxent utilizando 6 variables ambientales (batimetria, pendiente del fondo marino, distancia a la costa, distancia al frente de marea, temperatura superficial y concentracion de clorofila). Los mamiferos marinos se encontraron mas cerca de las areas frontales que al azar (9,48 km y 13,34 km, respectivamente). La profundidad, la distancia a la costa y la pendiente fueron las variables mas importantes en la distribucion de todas las especies. Balaenoptera sp., G. melas, G. griseus, L. australis y O. orca mostraron una distribucion costera ( EnglishThe San Jorge Gulf (SJG) is an important oceanographic region due to the influence of two tidal fronts, being one of the most productive sectors and with greater marine biodiversity in the Argentine Sea. The aim of this study was to identify which oceanographic variables best explained the presence of marine mammals and to explore the overlap of the predicted richness with the frontal areas of the SJG during the austral summer. The potential distribution of 9 species (Balaenoptera sp., Cephalorhynchus commersonii, Globicephala melas, Grampus griseus, Lagenorhynchus australis, L. obscurus, Mirounga leonina, Orcinus orca, Otaria flavescens) was modeled with Maxent using 6 environmental variables (bathymetry, seafloor slope, distance to the coast, distance to the frontal area, sea surface temperature and chlorophyll a concentration). Marine mammals were found closer to the frontal area than expected by chance (9.48 km and 13.34 km, respectively). Bathymetry, distance to the coast and seafloor slope were the most important variables in the distribution of all the species. Balaenoptera sp., G. melas, G. griseus, L. australis and O. orca showed a coastal distribution (