Coral reefs build their structures by both producing and accumulating calcium carbonate, and this is essential for the maintenance and continued vertical 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 ecosystems, 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 processes. Scientists have long known that reef ecosystems are in decline and that the amount of live coral on reefs is dwindling. But the paper, published in Nature Communications, is the first evidence that these ecological 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 erode. 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 positively 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 vertically, 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 deterioration 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.
They discovered that declines in rates of carbonate production were especially evident in shallow water habitats, where many fast growing branching coral species have been lost. The study compared modern day rates with those measured in the region over approximately the last 7,000 years. In key habitats around the Caribbean, the findings suggested that in waters of around five metres in depth, reef growth rates are now reduced by 60-70% compared to the regional averages taken from historical records. In waters of around 10 metres in depth, the rates are reduced by 25%.
The study also suggests that these key habitats must have a minimum of around 10% living coral cover to maintain their current structures. The amount of cover varies between sites, but some are already below this threshold and are therefore at risk of starting to erode. Given that previous studies have shown that coral cover on reefs in the Caribbean has declined by an average of 80 per cent since the 1970s, this raises alarm bells for the future state of reefs in the region. These changes have been driven by human disturbance, disease and rising sea temperatures, and are only expected to intensify as a result of future climate change.
University of Exeter: http://www.exeter.ac.uk
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Results of largest ever genetics study of a single population could also help refine dates for major events during human evolution Humans are evolving more rapidly than previously thought, according to the largest ever genetics study of a single population.
Latest genetic tests reveal another break in the male line, potentially undermining the legitimacy of the entire House of Plantagenet When scientists revealed last year that an adulterous affair had apparently broken the male line in Richard III’s family tree, they vowed to investigate further.
By 2016, Icelandic genetics company deCODE will have data on half the country's population. Releasing the data will be controversial, but could save lives
A clinical trial has shown that the drug aducanumab slows cognitive decline in people with Alzheimer's and reduces the amount of amyloid plaque in their brain
A leading researcher issues a call for pills that deliver a full course of treatment in one swallow.One of the world’s preëminent biomedical researchers is calling for a concerted effort by scientists to develop pills that would stay in the stomach or gut for weeks or months once swallowed, delivering one or more drugs continuously or over set intervals.
Two genes responsible for building up drug-resistance can easily be shared between a family of bacteria
When malaria parasites infect blood, they manufacture odor molecules that smell sweet to mosquitoes, scientists report. So how do these odors get from the bloodstream to the insects?
Researchers are developing new method of wireless deep brain stimulation.
Zoos belonging to World Association of Zoos and Aquariums filmed allowing shocking mistreatment of elephants, dolphins, lions, bears, penguins and whales
Owners of Highland Wildlife Park hope Victoria, 18, will get chummy with male Arktos during her stay in the Cairngorms