Biometric and biomass analysis of Quaternary Uvigerinidae (Foraminifera) from the Southern Brazilian continental slope

The relative abundance, test size, elongation index, volume, and biomass variations of the Uvigerinidae species were analyzed in 1921 tests from 42 samples of two cores obtained from the continental slope of the Western South Atlantic. Variations in uvigerinid distribution and their test metrics are discussed based on the main climatic and oceanographic changes through the last glacial cycle. The higher dominance of Trifarina angulosa during the interglacial stages suggests that this species is favored by a stronger influence of the warm, nutrient-poor and oxygen-rich North Atlantic Deep Water (NADW), and near-bottom currents. Uvigerinid richness, the number of larger and less elongated tests and the accumulated biomass increased during the glacial stages, when the lower continental slope was more influenced by the Circumpolar Deep Water (CDW) close to the bottom and nutrient-enriched surface waters. In this sense, these biotic descriptors have the potential to be applied as proxies in studies on the paleocirculation and carbon flows to the seafloor through the late Quaternary in the South Atlantic. A regression model was also formulated to convert the test length to the total test volume for Uvigerinidae, which can facilitate data acquisition in future studies, expanding their use as paleoceanographical proxies.

Automated summary

This study analyzed the characteristics of Uvigerinidae species on the continental slope of the Western South Atlantic and discussed their distribution and variations during the late glacial cycle. The dominance of Trifarina angulosa during interglacial stages suggests its preference for warmer, nutrient-poor, and oxygen-rich North Atlantic Deep Water. The study also highlights the potential use of biotic descriptors as proxies in studies on paleocirculation and carbon flows in the South Atlantic.