Effect of organic carbon flux and dissolved oxygen on the benthic foraminiferal oxygen index (BFOI)

Variations in oceanic primary productivity, flux of organic carbon to the sediments, and dissolved oxygen levels in the water column are thought to be important in the control of benthic foraminiferal test size, wall thickness, morphology, and species composition of assemblages by many foraminiferal paleontologists. Aspects of these processes should be reflected by the benthic foraminiferal oxygen index (BFOI) based on these foraminiferal characteristics. However, analyses indicate that the BFOI correlates most strongly with dissolved-oxygen levels in overlying water (R² = 0.81), weakly with oceanic primary productivity (R² = 0.55), and weakly with organic carbon flux to the sediments (R² = 0.51). Although both dissolved oxygen and organic carbon flux are main controlling factors for benthic foraminiferal assemblages, the BFOI is a useful indicator extracted from benthic foraminiferal assemblages for estimating the condition of dissolved oxygen in Cretaceous and Cenozoic oceans.