ASSESSING DENITRIFICATION AND OTHER STRATEGIES FOR PLANKTIC FORAMINIFERAL SURVIVAL UNDER DYSOXIC CONDITIONS

As the oxygen levels in the world’s oceans are decreasing, coastal zones that support few large animals (‘dead zones’) and open-ocean oxygen minimum zones (OMZs) are increasing. The expansion of deoxygenation has significant ecological consequences, impacting global climate through biologically-mediated carbon and nitrogen cycling changes. Understanding the survival strategies and biogeochemical contributions of organisms that tolerate very low-oxygen is, thus, critical. This project investigates the strategies that free-floating foraminifera, an important group of eukaryotic single-celled organisms, use to survive within the OMZ. A particular focus is whether these foraminifera can respire nitrogen, like certain foraminifera species living on/in the ocean floor, contributing significantly to global nitrogen cycling. Methods being employed include population surveys (species counts), molecular approaches (transcriptomics), geochemical analyses to ascertain N cycling, and cellular ultrastructure analyses to survey for putative symbionts or other cellular adaptations as noted previously in benthic foraminifera from low-oxygen habitats. This project supports two early-career female scientists, including one from an underrepresented group in geosciences, and at-sea and laboratory training for (under)graduate students from four universities. Our main outreach activity is discussed below.