When scientists predicted that 2015 would be the third global bleaching event on record, researchers at the Central Caribbean Marine Institute (CCMI) in Little Cayman went on high alert. Corals were expected to bleach and perhaps experience mass mortality near the end of the summer as seawater temperatures exceeded the thermal tolerance levels for most coral species.
Thanks to funding from the Edmund F. and Virginia B. Ball Foundation,CCMI has been able to monitor Little Cayman reefs before, during, and after the extreme temperature event.
As corals bleach, they pale in colour and may turn white, which makes colour a good proxy for stress levels. CCMI adapted a rapid response protocol using coral health charts with colour scales similar to paint samples found in home improvement stores. Snorkelers and divers, including undergraduate students and citizen scientists, were able to assist in collecting data and photos.
Between June and September 2015, when seawater temperatures increased to 30-31°C, approximately 25 per cent of Little Cayman’s corals turned pale or bleached white. By October, when the ocean reached its maximum summer temperature, almost 60 per cent of the surveyed corals had changed colour. Fortunately, storms and high winds brought relief to the reef. Seawater temperatures dropped below critical levels and, by November, colour was returning to the reef.
The good news is that most of the Little Cayman corals appear to be recovering after the elevated temperatures they experienced in 2015. CCMI will continue its surveys to record whether the corals experience any long term impacts of the bleaching event.
Dr Carrie Manfrino, CEO of CCMI expressed gratitude to the Edmund F. and Virginia B. Ball Foundationfor their support.
“Worldwide, coral reefs are in danger from rising sea temperatures in a variety of ways – being able to closely monitor any sudden or gradual changes to coral’s natural environment allows us to identify how exactly they are affected and to take measures to protect and in the future regenerate the most resistant corals. Without funding from generous organisations such as the Ball Foundation, this type of work would not be taking place,” she said.
The Central Caribbean Marine Institute is a US, UK, and Cayman Islands non-profit organisation whose mission is to protect coral reefs for the future by strengthening understanding of what contributes to resilience and by reinforcing discoveries that offer hope to restore the balance of healthy coral reefs. The CCMI engages children and communities in active coral reef conservation as a part of its Science and Society initiative. Public and private contributions support its work.