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A team from the St. Petersburg Coastal and Marine Science Center and the National Park Service conducted emergency fieldwork to protect corals during the ongoing Florida coral-bleaching event.

Bleached white Elkhorn coral shown under a shade cover installed to protect it in Dry Tortugas National Park, Pulaski Shoal
Shown here is a colony of the threatened Elkhorn coral, Acropora palmata, that has become "bleached," that is, lost all its algal symbionts (also called zooxanthellae) because of the summer 2023 ocean-heat wave. Pictured here is one of calcification stations located in Dry Tortugas National Park. When photographed on August 15, 2023, this coral was showing areas that were completely bleached but still alive, areas where the coral tissue still contained some symbionts, and areas that were already dead . The shade structure could help to reduce light stress that is problematic when corals are in a bleached state. For more information, view the image in the USGS Multimedia Gallery by clicking on it.

Coral reef ecosystems provide ecological and economic services by providing habitat for fish and other reef-dwelling species and by protecting shorelines from storms. As corals continue to perish from stressors such as coral diseases and rising ocean temperatures, those services are in jeopardy.

Ilsa Kuffner, Anastasios Stathakopoulos, and Joseph Terrano (USGS SPCMSC) joined a team from the National Park Service (NPS) led by Karli Hollister and Jordan Holder to safeguard threatened corals within Dry Tortugas National Park. Following that effort, the USGS team visited Biscayne National Park to conduct similar interventions, adding Ben Galbraith and Alex Modys from SPCMSC to the team for extra help. The corals are in peril because of a phenomenon known as “coral bleaching.” Corals become "bleached," that is, lose their algal symbionts (also called zooxanthellae) that provide corals with color, and more importantly, food, when ocean temperatures reach and remain above 87 degrees Fahrenheit. The current, ongoing bleaching event is being caused by unprecedented above average ocean temperatures being driven by both El Niño effects and global climate change. The longer that corals experience these elevated temperatures, the higher the chance that the corals will starve and perish.

The USGS and NPS teams are attempting to mediate the impacts of this bleaching event using three approaches: shading select corals that were already in nursery or experimental settings, temporarily enhancing feeding opportunities using dim lights at night to attract prey, and evacuating representatives of unique genetic lines of threatened species to land-based aquarium facilities. These actions are modest considering the spatially widespread populations of nearly all coral species that are being affected, but coral managers are optimistic they can help with coral recovery from this bleaching event.

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