Award: OCE-1760704

The project team completed 3 research cruises on the TX-LA shelf in the northern Gulf of Mexico in the 6 months following Hurricane Harvey in 2017-2018. The collaborative team collected samples on those cruises to characterize the plankton communities ranging from the smallest (pico- and nanoplankton) through larval fish that comprise the ichthyoplankton. The team also completed 5 grazing experiments on each cruise to quantify how plankton food webs were changing in the aftermath of the storm and the freshwater plume it introduced to the coastal ocean. The team was successful in documenting how plankton communities and food webs changed in the coastal ocean off Texas following Hurricane Harvey. At the base of the food web, biomass of the planktonic primary producers (phytoplankton) first increased and then decreased in the 3 weeks and 6 weeks following Harvey, respectively. These trends were relative to samples collected in the region in late July 2017, a month before Harvey made landfall. The decrease that occurred 6 weeks following the storm was much lower than the biomass typically seen in this region during Sept/Fall, based on samples analyzed from a long-term dataset (NOAA/GSMFC SEAMAP). These changes were most prevalent with the smallest phytoplankton, which also showed the highest rates of mortality by small, single-celled consumers (microzooplankton). These results suggest that the changes in phytoplankton biomass and community that we observed were likely due to a combination of both bottom-up and top-down (i.e. grazing) control on those organisms. The numerical abundance and diversity of mesozooplankton communities (organisms typically 0.02 ? 20 cm in size which consume both larger phytoplankton and microzooplankton), varied across the Texas shelf and over time following the hurricane. Post-storm, densities were highest in September and then decreased 10-fold in three weeks when sampled again in October. Mesozooplankton were consistently more abundant at stations closest to Galveston Bay and lowest in offshore waters. Diversity peaked at the mid-point along the shelf. Temporal patterns suggest mesozooplankton may be highly resilient to hurricanes, with community structure only altered for a few weeks after a storm. Ongoing analysis of historical SEAMAP mesozooplankton samples will elucidate if observed temporal patterns indicate seasonality or deviations from the norm in community structure following Hurricane Harvey. This project supported the research of two early-career faculty members (Robinson & Stauffer), two Ph.D. students at UL Lafayette who are basing at least part of their dissertations on this research, and three other graduate students and 10 undergraduate students who took part in research cruises, sample processing, and data analyses. We also engaged with K-12 classes in five states before, during, and after the research cruises through a Styrofoam cup activity and are rescheduling a science communication event on the project that was postponed in Spring 2020. The project has resulted in 10 presentations at scientific conferences, 1 manuscript submitted, and 2 more manuscripts in the revision process. Through this project, the PI and CoPI began working with a collaborative group that is working to advance a more general framework for understanding impacts of tropical cyclones on ecosystems from the ocean to land. Last Modified: 04/14/2020 Submitted by: Kelly Robinson