Unlocking Globorotaloides hexagonus as a Proxy for Past and Future Ocean Deoxygenation

The planktonic foraminifer Globorotaloides hexagonus thrives in low-oxygen waters and may serve as a quantitative proxy for reconstructing oxygen minimum zone (OMZ) intensity through time. This project will determine whether G. Hexagonus represents a single species or a complex of cryptic genotypes and assess how shell porosity reflects oxygen availability. Building on existing specimens from the Southeast Pacific (SEP) OMZ and new samples collected during the R/V Sonne SO315 cruise to the region, we aim to integrate genetic, morphological, and environmental data to distinguish genotypic from environmentally driven variation. We will use DNA sequencing, scanning electron microscopy, and morphometric analyses to link genotype and shell traits to measured oxygen conditions. Producing a genotyped dataset for G. hexagonus from the SEP OMZ will enable us to build and refine a framework for using shell porosity as an oxygen proxy, advancing reconstructions of past ocean deoxygenation and improving predictions of future OMZ expansion.