Award: OCE-1521564

In the surface ocean, microscopic algae called phytoplankton form the base of the ocean?s food chain. Through photosynthesis, phytoplankton are able to use energy from sunlight to transform carbon dioxide into hundreds of thousands of different organic molecules. Bacteria and other microorganisms that inhabit seawater consume these different phytoplankton-derived molecules as food and energy sources, an exchange that represents one the most rapid and crucial steps in the ocean carbon cycle. This National Science Foundation fellowship focused on characterization of a special class of sulfur-containing molecules called sulfonates (defined by their R-SO3- functional group) that represents a missing link in carbon and sulfur transformations in the ocean. Sulfur compounds released from the ocean have direct impacts on the chemistry of the atmosphere. Although the oceans are a major source of sulfur compounds, the role of sulfonates had not been well described. Because sulfonates had not been routinely measured by oceanographers, a method for sulfonate quantification was successfully developed. Using this new method, sulfonates were quantified in ~30 different phytoplankton and bacterial species. These observations indicate that sulfonates can be some of the most abundant molecules produced in eukaryotic phytoplankton cells, accounting for ~10% of the cellular organic sulfur. Sulfonate measurements were also made in natural ocean communities during three cruises in the North Pacific Ocean. Both spatial and temporal patterns were observed in sulfonate abundances. Spatially, sulfonate abundance appears to correlate with the abundance of their primary biological source, eukaryotic phytoplankton. Temporally, some sulfonates show strong diel patterns, likely a reflection of changes in cell size and photosynthetic activity of phytoplankton cells over the day-night cycle. Rate measurements of sulfonate consumption were performed while at sea and indicate rapid turnover times, with estimates of the entire pool being recycled in ~1 day. By pairing these chemical measurements with additional gene expression measurements, further insight has been gleaned into the specific organisms that produce and degrade sulfonates in the sea. Through this project, there is now a greater appreciation for the prevalence and role of sulfonates in the marine microbial food web. This work has provided the first intensive characterization of sulfonates in the marine environment in terms of their contribution to the ocean carbon cycle and marine ecosystem. This project supported interdisciplinary training in microbial ecology and marine chemistry for the fellow at the University of Washington. The fellow trained and mentored three undergraduate students, leveraging available programs at the University of Washington that aim to increase the number of first-generation, low-income, and/or minority students in STEM fields. These programs include the Genomics Outreach for Minorities Alliances for Learning and Vision for Underrepresented Americans (GenOM ALVA) Program and the McNair Program. In order to disseminate research topics and concepts in ocean sciences to a diverse demographic of high-school students in the Seattle area, the fellow provided research training to two local high-school science teachers. Under the direction of the fellow, the two teachers designed hands-on, active-learning classroom modules on marine microbiology and bioinformatics for their General Biology, Special Education Biology, and International Baccalaureate Biology courses. Dissemination of research findings to the broader scientific community was achieved through presentation of results by both the fellow and undergraduate mentees at national and international science meetings. Last Modified: 11/09/2017 Submitted by: Bryndan P Durham