The Cayman Islands are low-lying coral islands formed primarily from calcium carbonate deposits produced by marine organisms. Our coral reefs are the foundation of our islands, which are situated atop an ancient underwater mountain range known as the Cayman Ridge with steep underwater walls thousands of feet deep. Our reefs are essential components of large underwater reef systems that support a diverse array of marine life, providing habitat, breeding grounds, and food sources for numerous species, and contributing to the health and stability of our ocean environments. Protecting these ecosystems is crucial for maintaining our Caymanian way of life.
Cayman’s reefs are more than just tourist attractions—they form the backbone of the marine ecosystems which provide coastal protection and support fisheries that many Caymanians rely on. Yet in recent decades, Cayman’s coral ecosystems have been in crisis and the reefs that once teemed with vibrant life are dying. Unchecked human impacts like overfishing, coastal development, marine pollution and unmanaged waste water continue to degrade our oceans, while a rapidly changing climate forges ahead. Increasing temperatures and acidifying seas coupled with decreasing water quality and increasing pollution have left a coral reef ecosystem teetering on the brink of survival.
Despite looking like plants, corals are in fact tiny animals called polyps which live in colonies attached to hard surfaces on the sea floor. They are related to jellyfish and sea anemones but have a hard external skeleton that they slowly build by drawing calcium carbonate from the surrounding seawater. Coral reefs cover less than 0.1% of the ocean floor (a very small area, given the ocean’s vastness) but support an extraordinarily high level of biodiversity, providing habitat, food, and nursery grounds for about 25% of all marine species.
From algae grazing parrot fishes, and sea urchins, to waste processing shrimps, to sharks predating on the sick and dying, every species on the reef symbiotically contributes to the healthy functioning of the coral reef ecosystem. Uncontrolled overfishing has caused disparities in reef fish populations resulting in severely depleted reef health both locally and globally. Meanwhile, invasive species such as lionfish, along with indirect human activities have exacerbated this imbalance on reefs in Cayman and throughout the Caribbean.
Coral reef monitoring
It is estimated that global live coral coverage has approximately halved since the 1950s. Photographs of Cayman’s reefs from the 1970s show a much healthier reef with coral cover at around 80%. The Department of Environment (DoE) began conducting annual coral reef health assessments in each of the three islands in 1997. At that time, overall coral cover across the islands averaged around 25% but by 2023 that average declined to just 11% and has further declined in Grand Cayman to an average of around 6% in 2024.
Cayman was one of the first places in the Caribbean to use fixed camera photo-transects to take repeated pictures of the same sections of reef over time to track the change in coral cover. Today photogrammetry has become a powerful tool for DoE scientists to use overlapping photographs taken by divers to build accurate 3D models of landscapes, reefs, and structures. The resulting models allow scientists to more accurately measure coral cover, growth, and structural complexity while tracking changes after bleaching events, disease outbreaks, ship groundings, anchor damage and hurricanes.
Climate change & coral resiliency
The most significant driver of coral reef decline worldwide is climate change, and Cayman’s reefs are no exception. Coral animals live in a delicate partnership with tiny algae called zooxanthellae, which provide food to the coral through photosynthesis. When ocean waters become too warm however, this relationship breaks down as corals expel the algae, leaving their skeletons stark white—a phenomenon called coral bleaching.
The Caribbean has experienced several severe bleaching events in the past three decades, and Cayman’s reefs have been hit hard. The most devastating episodes occurred during the particularly hot summers of 1998, 2005, and 2017, when sea surface temperatures remained above the threshold for coral survival for extended periods. If the corals stay stressed and bleached for too long they will die. But if the temperature cools back to normal fast enough they can recover. This occurred after the 1998 bleaching event with many of Cayman’s corals seemed to survive and return to normal. However DoE photo-transects of the reef confirmed that, although corals could recover from bleaching, they were significantly weakened and susceptible to disease. If corals do not have enough time to recover between events their survival rates drop dramatically, leading to long-term reef degradation and greater vulnerability to coral diseases. The 2023 coral bleaching event was the most extreme and most prolonged on record when our reefs experienced 19-degree heating in a matter of weeks, exceeding thermal tolerances resulting in significant coral mortality. Cayman is currently at NOAA bleaching alert level 2 (Risk of Reef-Wide Bleaching with Mortality) for 2025.
Stony Coral Tissue Loss Disease (SCTLD)
Stony Coral Tissue Loss Disease (SCTLD) is an aggressive and lethal coral disease which first emerged in Florida in 2014. It quickly spread to coral reefs across the Caribbean region arriving in Grand Cayman in June 2020. Despite efforts to stop the spread by removing sick corals, closing dive sites, disinfecting dive gear, and even applying experimental antibiotic paste to sick corals, SCTLD spread completely around Grand Cayman within 18 months.
In August 2025, SCTLD was confirmed on the reefs along the western most tip of Little Cayman. Dedicated efforts from the public, stakeholders and sister islands dive operators to keep dive/snorkel gear and boat bilge water from contaminating sister island reefs likely led to the 5-year delay in SCTLD reaching Little Cayman. Lessons learned from the spread of SCTLD in Grand Cayman form the basis of disinfection response protocols.
Vigilant disinfection of dive and snorkel gear remains our best chance of slowing the spread and avoiding the transfer of the infection to Cayman Brac as all other interventions (including the antibiotic paste) have proven unable to stop the spread of the disease once it is established.
The Future of Cayman’s Corals
For the Cayman Islands, the loss of coral reefs would mean more than the disappearance of colorful dive sites. It would quite literally erode the very foundation of our islands, in addition to the marine ecosystem we depend on for coastal protection against storms, food security, tourism revenue and cultural identity. Protecting our reefs will require both a local, regional and global commitment to reducing greenhouse gas emissions, improving wastewater management, fisheries management, and fostering a culture of marine stewardship among residents and visitors alike.
Learn more at www.doe.ky/coral