The distribution of benthic Foraminifera with respect to oxygen concentration and organic carbon levels in shallow‐water Antarctic sediments

Abstract

The vertical distribution of living benthic Foraminifera from 12 sediment cores (12.2–18.3‐m water depth) collected in Explorers Cove and Winter Quarter’s Bay, McMurdo Sound, Antarctica, was determined and compared with pore‐water oxygen, sedimentary organic carbon, and grain size. Oxygen measurements were made with microelectrodes to depths greater than the anoxic‐oxic interface (0.1 ml O 2 liter −1 ; 4.4 µ M O 2 kg −1 ). Sedimentary organic carbon contents were low (0.1–0.5% dry wt). Maximal standing stocks, as determined by adenosine triphosphate (ATP) assay, occurred in the top 0.5 cm of all cores. No distinct segregation in species occurrence with respect to depth in the sediment was observed. Individuals of both calcareous and arenaceous species ( Cassidulinoides porrectus, Cribrostomoides jeffreysii, Globocassidulina cf. G. biora, Portatrochammina antarctica, Psammosphaera parva ) were found living in anoxic sediment layers. Relative to ATP, Rose Bengal staining grossly overestimated and Sudan Black B underestimated living standing stocks.