Coral reefs build their structures by both producing and accumulating calcium¹ carbonate, and this is essential for the maintenance and continued vertical²（垂直的） growth capacity of reefs. An international research team has discovered that the amount of new carbonate being added by Caribbean coral reefs is now significantly below rates measured over recent geological timescales, and in some habitats is as much as 70% lower. Coral reefs form some of the planet's most biologically diverse ecosystems³, and provide valuable services to humans and wildlife. However, their ability to maintain their structures and continue to grow depends on the balance between the addition of new carbonate, which is mostly produced by corals themselves, set against the loss of carbonate through various erosional（侵蚀） processes. Scientists have long known that reef ecosystems are in decline and that the amount of live coral on reefs is dwindling⁴. But the paper, published on DATE TBC in Nature Communications, is the first evidence that these ecological⁵ changes are now also impacting on the growth potential of reefs themselves.

 

Professor Chris Perry of the University of Exeter, who led the research, said: "Our estimates of current rates of reef growth in the Caribbean are extremely alarming. Our study goes beyond only examining how much coral there is, to also look at the delicate balance of biological factors which determine whether coral reefs will continue to grow or will erode⁶. Our findings clearly show that recent ecological declines are now suppressing the growth potential of reefs in the region, and that this will have major implications for their ability to respond positively⁷ to future sea level rises.

 

"It is most concerning that many coral reefs across the Caribbean have seemingly lost their capacity to produce enough carbonate to continue growing vertically⁸, whilst others are already at a threshold where they may start to erode. At the moment there is limited evidence of large-scale erosion or loss of actual reef structure, but clearly if these trends continue, reef erosion looks far more likely. Urgent action to improve management of reef habitats and to limit global temperature increases is likely to be critical to reduce further deterioration⁹ of reef habitat."

 

The team was funded by the Leverhulme Trust (UK), through an International Network Grant. It included scientists from James Cook University and The University of Queensland in Australia, from The University of Auckland in New Zealand, Memorial University in Canada, and the University of Maine in the USA. They examined rates of carbonate production across 19 reefs in the four Caribbean countries of the Bahamas, Belize, Bonaire and Grand Cayman.

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