NSF Award
2347307
It's been hot, record hot in the Western Atlantic. In the shallow seas surrounding the Florida Keys, a region that harbors the world’s third longest coral barrier reef and the only one in the continental USA, water temperatures peaked in late July 2023 at 101F. Even at 30ft deep on the coral reef temperatures reached an unprecedented 90F, unleashing a wave of fish kills, corals bleaching, and dying octocorals and sponges. Marine scientists are concerned about the effects of this unprecedented climatic event on coral reefs in the Caribbean and Florida, and there has been a flood of media press as well. Yet, the focus has been almost exclusively on corals. Although corals provide the structural foundation for coral reefs, the functioning of coral reef ecosystems also depends on the health of other reef organisms. Of particular importance are sponges, which are key to capturing and recycling nutrients and carbon from the surrounding seas – a process referred to as “pelagic-to-benthic coupling”. This project (a) assesses the damage of the summer 2023 heatwave on shallow water and reef dwelling sponges in the Florida Keys, (b) tests the effects of high seawater temperatures and associated low oxygen levels on sponges, and (c) using those data, develops a model to help predict the effect of future heatwaves on sponges and the ecological services they provide to the ecosystem. The project includes training for undergraduate and graduate students at a minority-serving institution and public outreach and engagement with K-12 students through a partner NGO. Project results inform resource managers with the Florida Keys National Marine Sanctuary.<br/><br/>Seawater temperatures in the Caribbean rapidly rose to unprecedented levels in summer 2023, unleashing a cascade of disturbance to coral reef ecosystems. The event galvanized scientists, resource managers, and the media into action but nearly all of that attention focused on corals. Corals provide the structural foundation for coral reefs, but the functioning of coral reef ecosystems as nutrient sinks and recyclers in otherwise oligotrophic seas is highly dependent on another taxon: sponges. Sponges are key to pelagic-to-benthic coupling and nutrient recycling on coral reefs and coastal backreef habitats, yet almost nothing is known of the effect of extreme environmental stress on sponge survival and function on coral reef ecosystems. The team is (a) using field surveys and leveraging pre-event baseline data to assess changes in sponge community structure across an inshore to offshore gradient in the Florida Keys; (b) using mesocosm experiments to examine the effects of elevated seawater temperatures and low dissolved oxygen on filtering of microbes, consumption of dissolved organic material, and fixation of nitrogen by sponges that differ in phylogeny, morphology, microbiome, or habitat; and (c) integrating these data to model projected changes in coastal and coral reef pelagic-to-benthic coupling. The results of this project advance understanding of the functional role of sponges in coral reef ecosystems in a changing climate.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
