Off the coast of Florida, researchers and trained volunteers are working to restore coral reefs and study their ability to withstand rising ocean temperatures caused by climate change. The efforts are part of the University of Miami’s long-running "Rescue a Reef" program, which combines conservation, scientific research, and public education to address the challenges facing Florida’s coral ecosystems.

During recent dives at Rainbow Reef, situated about three miles offshore from Key Biscayne, the team planted young coral colonies and monitored existing coral health. Program manager Devon Ledbetter noted that some species exhibit greater resilience to thermal stress, allowing them to survive and recover better than others amid warming waters. These adaptable species are a focus of ongoing investigations aimed at identifying corals that might endure the increasingly frequent heat-related events.

Coral reefs play a critical ecological role, providing habitat for a wide range of marine life and acting as natural barriers that protect coastlines from storm damage and erosion. However, the reefs in Florida face mounting threats, especially from marine heat waves. A record-breaking heat wave that began in 2023 led to the functional extinction of two key reef-building corals, elkhorn and staghorn, within Florida’s Coral Reef system. This loss underscores the severe impact of warming oceans.

The National Oceanic and Atmospheric Administration (NOAA) has indicated that the fourth global coral bleaching event—which includes widespread coral stress and mortality from heat—likely ended by mid-2025. Nevertheless, NOAA warned that an impending strong El Niño could trigger another spike in bleaching events, potentially affecting Florida waters once again.

Fieldwork involves several methods of coral propagation. Certain fast-growing corals are suspended on structures called "coral trees," while others are affixed to frames secured to the seafloor or mounted on plugs planted directly onto the reef. Protective “predation umbrellas” are used to shield young corals from fish grazing. Researchers also employ color reference charts to measure coral pigmentation, an indicator of coral health, allowing them to detect early signs of heat stress.

Coral animals, known as polyps, rely on symbiotic algae living within their tissues for energy. Elevated temperatures or pollution can cause these algae to leave, resulting in coral bleaching, which leaves the coral vulnerable to disease and mortality. Anecdotal evidence from the program suggests that species such as Mountainous Star Coral show comparatively high resilience to bleaching.

Since its inception in 2015, the Rescue a Reef program has planted hundreds of coral colonies each year—615 so far this summer, including 228 involved in thermal stress studies. Findings from the program are shared with state environmental and wildlife authorities to guide broader conservation efforts. Despite the end of the latest global bleaching event, NOAA research published in the journal Coral Reefs shows that sea surface temperatures remain significantly elevated compared to levels from 25 to 30 years ago, posing ongoing risks to coral survival.