Award: OCE-1810616

In September 2017, two major hurricanes - Hurricane Irma and Maria – hit the island of St. Thomas (U.S. Virgin Islands) within two weeks of each other. The double-whammy of these devastating storms caused unprecedented impacts on shallow reefs dominated by some of the most diverse sponge communities in the Caribbean. With the decline in corals over the last several decades, sponges now represent significant biodiversity on Caribbean reefs and provide critical ecosystem services, including habitat and food, reef consolidation, water filtration and biogeochemical cycling. Whereas many studies have evaluated the impacts of hurricanes on coral communities, to date, virtually nothing is known about resilience, recovery, recruitment and early successional stages of Caribbean sponge communities in response to natural disasters. This project took advantage of the rare opportunity to evaluate short- and long-term resilience of sponges to extreme storm events on Caribbean reefs. Repeated surveys, experimental manipulation and genetic sampling were used to address questions related to sponge resilience. Results indicated an overall decline in total sponge cover following the back-to-back hurricanes, but that there were also winners and losers in the sponge communities. Upright sponges showed significant declines white encrusting sponges increased in relative abundance post-hurricanes. Surprisingly, although coral cover appeared to decline slightly, results did not detect significant changes in coral cover at our sites. A coral disease outbreak affected two of the sites at the time of the final cruise and has since spread throughout the U.S. Virgin Islands. This unprecedented disease outbreak ultimately resulted in a more dramatic decline in coral cover than did the hurricanes. Results also indicated that sponge recruitment and regrowth start rapidly after the hurricanes. Sponge communities at some sites showed large changes due to the hurricanes and after 2.5 years have not recovered to pre-hurricane states. This project brought together graduate students, an early-career post-doc, as well as established research faculty on four research cruises which resulted in many opportunities for multi-level mentoring and cross-training. Over the course of the project, one post-doctoral research associate from an under-represented minority (URM) background, 17 graduate students (12 female, 5 male; 4 from URM backgrounds), 1 female undergraduate, 3 female technicians, and a St. Thomas-based female resource manager were trained in field and laboratory methods focused on sponge community analysis. Outcomes included the post-doctoral associate going on to become a tenure track Assistant Professor at Harbor Branch Oceanographic Institute. Other project outcomes have so far included one peer-reviewed journal article as well as presentations at local, regional, and international conferences. Last Modified: 05/23/2022 Submitted by: Marilyn Brandt