CCMI RELEASES 2024 HEALTHY REEFS REPORT CARD – THE RESULTS ARE SEVERE, BUT FISH POPULATIONS AND RESILLIENT CORAL RESTORATION OFFER HOPE

Little Cayman, Cayman Islands; 4^th July 2025 – The Central Caribbean Marine Institute (CCMI) has just released the 2024 Healthy Reefs report card, which visualises the results of CCMI’s annual monitoring programme for 2024, the first year of monitoring after the 2023 marine heatwave and the most extensive coral bleaching event on record.

Through the Healthy Reefs campaign, CCMI has been monitoring the reefs of Little Cayman for 26 years. This long-term data set allows CCMI’s researchers to understand trends and changes over time and make informed decisions to protect coral reefs. The newly released report card shows the greatest reduction in coral cover and reef condition recorded through CCMI’s surveys through the 26-year monitoring period. 

The report card highlights that cover reduced from 26% in 2023 to 9.8% in 2024 following the mass coral bleaching event. This is the lowest coral cover recorded in CCMI’s surveys since 1999, with a previous all-time low in 2005 of 15%. The condition of the reefs also declined from 90% of reefs in at least ‘good’ condition in 2023 to only 18% in 2024. The results are shocking, but there is hope. Most of the coral decline can be attributed to ‘weedy’ corals that are more susceptible to increased temperatures and typically grow faster and contribute less to overall reef structure and integrity. The key reef-building boulder corals also bleached but showed much higher rates of recovery post-bleaching and lower mortality. 

The presence of macroalgae also increased in CCMI’s 2024 surveys from 30% to 37%, which is a common occurrence on reefs post disturbance. However, managing these levels of macroalgae on a reef is a crucial element of supporting reef recovery as when left unchecked, macroalgae can colonise bleached corals and out-compete them for space on the reef. One of the main ecological processes that controls macroalgal levels is grazing from herbivorous fish, such as parrotfish. 

Fortunately, years of marine management in Little Cayman have protected key species such as parrotfish. The 2024 report card also reveals an exponential increase in parrotfish density (the number of individuals in a specific area) from 2023 to 2024. This is likely to be in response to the increase in food availability in the form of macroalgae. This significant increase could be the key to controlling levels of algal overgrowth on Little Cayman’s reefs and buying time for corals to recover from the impact of 2023.

Overall, what does this mean for the reefs? The loss of some coral species means that the reefs will lose habitat complexity which can impact a reef’s ability to provide shelter for marine species and maintain the benefits that communities rely upon, such as coastal protection. However, the large increase in fish populations, largely due to the high level of protection in Little Cayman, provides hope. 

Similarly, CCMI researchers have been working to reverse the damage done to the CCMI coral nursery which was dramatically reduced in the 2023 marine heatwave. Over the past year, the nursery has been re-stocked from 17 fragments to nearly 220. Each fragment is a highly resilient genotype (or genetic variant) that was able to withstand and survive the 20+ weeks of elevated water temperatures in summer 2023. These resilient corals have also recently survived and recovered from an outbreak of coral disease and continue to grow at a rate of nearly 1cm per month. These corals continue to contribute to the marine biodiversity of Little Cayman through annual spawning, increasing the wild population of genetically resilient corals and contributing to overall reef recovery. 

The next few years will be critical for Little Cayman’s coral reefs, but the protections in place, remote location, and overall healthy supporting ecosystem may just give these historically resilient reefs an edge to recover and persist through the ever-pressing threats of climate change. 

Continued protection, alongside research and active conservation, is crucial in conserving this ecosystem at such a vulnerable stage in its history to ensure it can persist through the threats of climate change and adapt to a changing ocean.

CCMI continues to lead pioneering research into how we can support these reefs to acclimatise and adapt to the threats they face, partnered with conservation and immersive education to safeguard coral reefs for future generations. 

For CCMI to continue striving to conserve marine biodiversity in the face of increasing pressures, the support of corporate sponsors that commit to multi-year funding of these essential efforts is invaluable. CCMI would like to express deepest gratitude to this year’s Healthy Reefs sponsors, Wheaton Previous Metals International Ltd, Fosters Supermarket, Cayman Island Department of Tourism, Cayman Water, and Knighthead and CCMI’s coral restoration sponsors, The Ernest Kleinwort Charitable Trust, the UK Government’s Darwin Plus Programme and the AALL Foundation. 

Read the full 2024 Healthy Reefs Report Card here: 

https://reefresearch.org/wp-content/uploads/2025/05/Healthy-Reefs-Report-Card-2024-FINAL.pdf

Read more about CCMI’s Healthy Reefs Programme here: https://reefresearch.org/what-we-do/research/healthy-reefs/

Watch this mini documentary to find out more about CCMI’s coral restoration programme: https://www.youtube.com/watch?v=tdSwefBZvSw&t=3s

Read more about CCMI’s research here: https://reefresearch.org/what-we-do/research/resilience/