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Caribbean coral reef inhabitants critical in determining future of reefs

University of Exeter

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IMAGE: Diadema are rare on Caribbean reefs now but used to be very important bioeroders. Their decline, due to disease, has been one major reason why erosion rates are now much... view more

Credit: University of Exeter

New research led by the University of Exeter has found that species that live in and erode coral reefs will play a major role in determining the future of reefs.

The research, which is published in the journal Proceedings of the Royal Society B, highlights the delicate balance that exists between bioerosion and carbonate production on coral reefs.

Coral eroders, termed bioeroders, include species of sea urchins, sponges, parrotfish and microorganisms, known as microendoliths. Erosion occurs as a result of feeding and during the creation of living spaces and is a natural process on all coral reefs.

Professor Chris Perry from Geography at the University of Exeter said: "Our study shows that the future health and growth potential of coral reefs is of course in part dependent on rates of coral carbonate production, but that it is equally dependent, on the species that live in and on them, and which act to erode carbonate.

"If bioeroding species increase in number, and erosion rates increase relative to carbonate production, then this could spell trouble for many Caribbean coral reefs."

On 'healthy' coral reefs, bioerosion rates can be high, but more carbonate is typically produced than is lost to biological erosion. However, rates of carbonate production have slowed on many Caribbean coral reefs and coral cover has declined dramatically since the early 1980s. Despite this, marked shifts to states of net coral reef erosion have not widely occurred.

This new research shows that this is because bioerosion rates have also been reduced in recent years due to disease and overfishing and that this has acted to partially offset the lower rates of coral carbonate production. Were historical levels of bioerosion to be applied to today's reefs there would be widespread destruction, threatening many of the benefits that reefs provide to society.

Major management efforts are directed at protecting at least one major group of bioeroders, the parrotfish. This will benefit reefs because although parrotfish erode reef substrate, the advantages they offer through the removal of fleshy macroalgal cover and promoting coral recruitment outweigh the negative effects of substrate erosion.

"In essence, we need to work towards restoring the natural balance of ecological and geomorphic processes on coral reefs. From a bioerosion perspective this may seem counter-intuitive, but these species also play a critical role in maintaining reef health." said Professor Perry.

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This work was carried out in collaboration with The University of Auckland, New Zealand; Memorial University, Canada; James Cook University, Australia; the University of Maine, USA and the University of Queensland, Australia.

It was funded by a Leverhulme Trust (UK) International Research Network Grant.

About the University of Exeter

The University of Exeter is a Russell Group university and in the top one percent of institutions globally. It combines world-class research with very high levels of student satisfaction. Exeter has over 19,000 students and is ranked 7th in The Times and The Sunday Times Good University Guide league table, 10th in The Complete University Guide and 12th in the Guardian University Guide 2014. In the 2008 Research Assessment Exercise (RAE) 90% of the University's research was rated as being at internationally recognised levels and 16 of its 31 subjects are ranked in the top 10, with 27 subjects ranked in the top 20. Exeter was The Sunday Times University of the Year 2012-13.

The University has invested strategically to deliver more than £350 million worth of new facilities across its campuses in the last few years; including landmark new student services centres - the Forum in Exeter and The Exchange on the Penryn Campus in Cornwall, together with world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute. There are plans for another £330 million of investment between now and 2016.

http://www.exeter.ac.uk

For further information:

Jo Bowler, Science Press Officer
j.bowler@exeter.ac.uk
Office: +44(0)1392 722 062
Mobile: +44(0)7827 309 332
Twitter: @UoE_ScienceNews
For urgent enquiries outside nomal office hours please ring +44(0)7789 942 505 or email pressoffice@exeter.ac.uk

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