SCRIPPS INSTITUTION OF OCEANOGRAPHY FACULTY CANDIDATE SEMINAR: Human Health and the Oceans
DATE: April 17th, Tuesday, 1:00 p.m.
LOCATION: Eckart Lecture Hall
SPEAKER: Frank Stewart, Ph.D.
Georgia Institute of Technology
TITLE: From genes to ecosystems: microbial consequences of ocean oxygen loss
Marine oxygen minimum zones (OMZs) are expanding with human alterations of ocean ecosystems. OMZs support complex microbial assemblages with major roles in ocean biogeochemistry. The integration of genomic analyses with coupled biogeochemical measurements is enhancing our understanding of OMZ microorganisms, revealing a richness of metabolic processes structured along the vertical redox gradient and previously unrecognized linkages between elemental cycles. Recent work by our lab has identified novel clades of OMZ bacteria mediating anaerobic methane and sulfide oxidation coupled to denitrification, as well as previously unrecognized adaptations to anaerobic metabolism by the world's most abundant bacterium and a ubiquitous bacterium mediating anaerobic ammonium oxidation. This talk highlights these and other OMZ processes in relationship to key environmental drivers, including water column chemistry and the microscale partitioning of communities between particle-associated and free-living microniches. Collectively, work by our lab, and that of others, is helping transform our understanding of microbial niche space in OMZs. By studying how oxygen constrains microbial diversity, activity, and microbe-chemical interactions, we hope to understand how de-oxygenation will affect chemical cycles, ecosystem structure, and the human-ocean interface in a changing ocean.