Fish return to Little Cayman but reefs still at risk

(CNS): The number of fish on the reefs off Little Cayman has nearly doubled since 1999, when the first marine protections were rolled out, according to the Annual Reef Report Card by the Central Caribbean Marine Institute. Research scientists at CCMI also found that the waters now contain roughly three times the total biomass of marine life as a result of the protections around the island and low human activity on the reefs.

Despite the good news that fish numbers and density are growing and coral cover has remained stable, there are numerous vulnerabilities that continue to put at risk some of the healthiest remaining reefs in the entire region. These vulnerabilities are compounded by increases in water temperature and other climate change-related factors.

In a presentation about the reef report, CCMI Director of Research Dr Gretchen Goodbody-Gringley also raised concerns about future threats.

“The major thing we need to worry about in Little Cayman is more coastal development and the sewage,” she said, warning that too much sewage will change the eco-system completely and put the relatively healthy reefs now at even greater risk. Keeping development to a minimum was one of the best ways of keeping the island’s reefs healthy and resilient so they could withstand the major climate change threats, she said.

After conducting the survey last year, the scientists have found that while coral cover remains consistent at around 22%, with only a 2% decline in the last 25 years, there are shifts in the species dominating the reef. There are now more small, weedy corals, while large, reef-building boulder corals are in decline, and overall, coral size is decreasing. Researchers say the change in the dominant species is due to a decline in baby corals, a problem throughout the Caribbean region.

“If there is a significant bleaching event, ever more likely in currently warming ocean conditions and in El Niño years like 2023, the coral populations are at great risk,” the scientists warned in a press release about the survey.

They are nevertheless encouraged by the relative overall health of Little Cayman’s reefs. The increasing fish biodiversity, or species richness, is particularly encouraging as this is crucial for the health and resilience of complex reef ecosystems, the CCMI researchers said.

“These increases appear to be an effect of strong protection by the Cayman Islands Government, namely significant protection aimed at the Nassau grouper population enacted in 2016 and expansion of Marine Protected Areas (MPAs) in 2021. Nearly 75% of Little Cayman’s surrounding reefs are now marine protected areas,” they added. “CCMI’s long-term survey data shows year after year that there is higher biomass inside protected areas than outside.”

Major increases in 2020 and 2021 may have been influenced by COVID-19 because of reduced overall activity on the reef, the scientists believe.

In this latest survey, 87% of the reefs surveyed were in ‘good’ or ‘very good’ health. The diverse, healthy marine life that populates Little Cayman’s unique underwater topography has elevated the island’s marine protected areas to be one among only seven sites in the UK and overseas territories to be advanced for UNESCO World Heritage status.

Dr Goodbody-Gringley also spoke about the decline in algae and the increase in parrot fish and other critical reef herbivore fish in the water around Little Cayman. Parrot fish density has increased by 47% since 1999.

While the reefs are in comparatively good health, they still face significant threats, and the scientists are urging for even more protection to help the corals remain resilient in the face of warming seas, as the evidence shows that protections are helping them survive.

“There is an urgent need for further research into coral resiliency so that we may understand how corals may survive in the changing climate and future threats,” the researchers stated. “Coral reefs are critically important ecosystems facing increasing threats, and our work to create a sustainable, hopeful future for coral reefs is even more urgent than ever.”

During her presentation, Dr Goodbody-Gringley noted that the decline in fish on all of the reefs around the Cayman Islands began with over-fishing, but climate change and development are now the most pressing challenges to the future of Little Cayman.

See the detailed presentation of the results below on CCMI’s YouTube channel
and on the CCMI website.