Environmental Science and Engineering Seminar

The dynamics of oxygen minimum zones along continental margins, and their potential for future expansion, are important because of their intersection with global biogeochemical cycles and because of their far-reaching impacts on ocean ecosystems. However, the impacts of transient deoxygenation on biogeochemical cycles of carbon, nitrogen, sulfur, and iron at the sea floor are not well established and are the focus of the presented study. The oxygen-deficient Santa Barbara Basin is home to the so far largest mapped mat of giant sulfur-oxidizing bacteria. Our study tests the overarching hypothesis that deoxygenation triggers a positive feedback loop between sulfur-oxidizing mats at the sea floor that consume hydrogen sulfide, a sulfur species that can be toxic to higher organisms, and an underlying community of bacteria that produce hydrogen sulfide via organoclastic sulfate reduction. This seminar will present data from our NSF-funded seagoing expedition to the Santa Barbara Basin with R/V Atlantis, ROV Jason, and AUV Sentry in Fall 2019. I will introduce some of the in-situ methods we use to study biogeochemical processes and provide an overview of geochemical gradients, solute fluxes, and microbial processes we acquired so far. Come an enjoy the wonderful live of microbes in the muds of the ocean.