Recent Ostracod Fauna of the Western Ross Sea (Antarctica): A Poorly Known Ingredient of Polar Carbonate Factories

Ostracoda are a minor but recurrent component of Southern Ocean marine carbonate factories, and their low-Mg calcitic skeletal mineralogy helps in ensuring a noteworthy post-mortem resilience. Our study, based upon surface sediment occurrences, contributes to the better definition of their distribution vs. potential controlling factors in Antarctic waters. The ostracod fauna from the Western Ross Sea Shelf appears dominated by Australicythere polylyca, Australicythere devexa, Xestoleberis rigusa, Loxoreticulatum fallax, Cativella bensoni, Austrotrachyleberis antarctica and Patagonacythere longiducta, colonizing a variety of shelf environments along a wide bathymetric range. The abundance and richness values correlate well to nutrient distribution and sediment supply, primarily related to the circulation of different oceanographic regimes affecting the floor of the Ross Sea Shelf. Circumpolar Deep Water could represent the main factor controlling the distribution of ostracods. Similar results (high abundance and richness in ostracod values) were also recorded in the Terra Nova Bay and in a nearby area characterized by warm water rich in nutrients and composed of water of circumpolar origin flowing from the open ocean southwards onto the continental shelf. Particulate Fe (pFe), in suspended particulate matter (SPM), and other particulate trace metals in TNB could support the hypothesis that biogenic iron may significantly contribute to the bioavailable iron pool, sustaining both primary production and ostracod fauna richness in this area.