Living (Rose Bengal stained) benthic foraminifera were examined in multicore samples collected at depths ranging from 580 to 1,270 m from the Tasman Sea and southern margin of Australia. This study presents an initial overview of the deep-sea foraminifera living on these margins. Based on widely separated cores, there appears to be no correlation between foraminiferal abundance and species with ocean depth, seafloor grain size, oxygen availability, temperature, or particulate organic carbon. Although more work is needed, this study suggests environmental factors affect foraminiferal populations in a complex manner in the study area. The presence of species typical of shelf and shallow water environments in cores collected below 200 m water depth suggests a possible redistribution from shallower areas. In the ten samples from the 0-1 cm interval for the >150 mu m size fraction, 37 unique species were found. No more than four species overlapped across sites. Surprisingly, no significant correlations were observed egans, Uvigerina asperula, and Melonis affinis) and environmental parameters. Considerable environmental heterogeneity between sample sites, such as oxygen availability, grain size, and other factors associated with ocean circulation, is clearly evident. Based on observed assemblages, foraminiferal populations in the region appear influenced by dynamic and heterogeneous seafloor environments. This study serves as one of the few investigations of its kind to examine the ecology and diversity of contemporary deep-sea benthic foraminiferal communities along the southern and southeastern Australian margin, and highlights the potential ecological impacts of the heterogeneity and complexity of seafloor environments in the region. Additional work is necessary to further test and evaluate these hypotheses, and this research provides a foundation for future observations of living benthic foraminifera in the region.

The negative consequences of fossil fuel burning for the oceans will likely include warming, acidification and deoxygenation, yet predicting future deoxygenation is difficult. Sensitive proxies for oxygen concentrations in ancient deep-ocean bottom-waters are needed to learn from patterns of marine deoxygenation during global warming conditions in the geological past. Understanding of past oxygenation effects related to climate change will better inform us about future patterns of deoxygenation. Here we describe a new, quantitative biological proxy for determining ocean paleo-oxygen concentrations: the surface area of pores (used for gas exchange) in the tests of deep-sea benthic foraminifera collected alive from 22 locations (water depths: 400 to 4100 m) at oxygen levels ranging from ~ 2 to ~ 277 μmol/l. This new proxy is based on species that are widely distributed geographically, bathymetrically and chronologically, and therefore should have broad applications. Our calibration demonstrates a strong, negative logarithmic correlation between bottom-water oxygen concentrations and pore surface area, indicating that pore surface area of fossil epifaunal benthic foraminifera can be used to reconstruct past changes in deep ocean oxygen and redox levels.