Dissolved oxygen affinities of hundreds of benthic foraminiferal species

Abstract

Over the past decades, fossil assemblages of benthic foraminifera have been used to reconstruct the variability of oxygen-depleted areas, including oxygen minimum zones. These areas currently represent almost a tenth of the global oceans' surface area, and further expansion is expected due to global warming; with major impacts on marine ecosystems, biodiversity, and fisheries. To predict their future evolution, accurate estimates and quantification of past oceanic oxygenation are needed, and thus consistent calibration of the $\left(O_2\right)$ estimation transfer functions is required.

Here, we combine the BENFEP database that compiles all the benthic foraminiferal census data published for the East Pacific Ocean, with dissolved oxygen data interpolated from the WOA18 and GLODAPV2.2022 databases, to describe the oxygen affinities of the 1526 benthic foraminiferal taxa from the BENFEP database among 1691 samples. The affinities of the most common 202 species of the database are detailed here. For each of these taxa, the range of oxygen concentration, average $\left(O_2\right)$ value where the species is usually found, and $\left(O_2\right)$ value associated with its peak in relative abundance are listed and used to assign each taxon to the oxygen categories anoxic, dysoxic, suboxic, low oxic, and high oxic.

Finally, using the relative abundance of each of these five oxygen assemblages and their associated taxa, transfer function indices of dissolved oxygen estimation were refined. The new ${\mathrm{BFA}}_{\mathrm{ex}}$ extends the range of applicability of the formerly published BFA index, here updated using all the available samples $\left({\mathrm{BFA}}_{\mathrm{up}}\right)$ and extended from 0.04 to 2.58 mL L⁻¹ to 0.02–6.62 mL L⁻¹.