Calcareous microorganisms as indicators of oceanographic conditions in South West Atlantic Ocean

The results of multivariate analysis applied to the associations of benthic foraminifers and ostracods from surface sediments of the north Argentine continental shelf are presented in this study. We evaluated the distribution patterns and ecological preferences of species found in modern sediments from the north Argentine continental shelf, at depths between 15 and 130 m. We identified 61 species of foraminifers corresponding to the orders Rotaliida, Miliolida, Lagenida, Buliminida, Lituolida and Trochamminida, in addition to 18 species of ostracods that belong to the suborder Podocopina. The distribution of the ostracods Bradleya kaeslery Ramos, Coimbra and Whatley was extended to higher latitudes. It was determined that water depth and temperature were the factors that most affected the distribution of both types of microorganisms. Based on these data, we established three physiographical zones, which could be linked to the different water masses. In addition, the western limit of the Malvinas current at 80 m of water depth was corroborated. Our study highlights the potential use of benthic foraminifers and ostracods individuals as bioindicators for identifying oceanographic conditions in the Argentine continental shelf.