Maldives' reef rescue

Getting rid of predators such as crown-of-thorns starfish helps corals overcome bleaching.

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A crown-of-thorns starfish in the Maldives

A crown-of-thorns starfish in the Maldives © Daniela Dirschel / Getty

 

Community efforts to remove predatory starfish are helping two coral reefs in the Maldives offset the worst impacts of bleaching, scientists say.

Steve Newman, head of conservation at ecotourism operator Banyan Tree, says that volunteers have removed more than 6,000 crown-of-thorns starfish and just over 1,000 pin cushion seastars since 2008.

“Removal efforts conducted by staff and guests were critical in maintaining high coral cover on both [the islands of] Ihuru and Vabbinfaru,” Newman says.

Though both species are natural inhabitants of reefs in the Maldives, when coral is weakened by bleaching caused by higher sea temperatures, they exploit its fragile state and can eliminate it from an area.

The ‘reef rescue’ initiative began back in 2001 following a serious bleaching episode in 1998, and it continues today as regular, fortnightly trips to Ihuru and Vabbinfaru.

Banyan Tree says these act as an early warning system, helping conservationists to spot the onset of outbreaks before they overwhelm the coral.

Elsewhere in the Maldives the picture is much gloomier. On some sites where there has been no starfish removal, coral cover has been reduced by as much as 95 per cent following outbreaks. Other operators need to follow Banyan Tree’s approach, Newman says.

A survey carried out in 2016 found that higher-than-usual sea temperatures, exacerbated by the phenomenon of El Niño, had led to more than 60 per cent of reefs in the Maldives being hit by bleaching.

When temperatures rise, corals expel the algae with which they have a unique relationship, leading to bleaching and in many cases, the death of the coral polyps. 

 

Find out more on the Marine Research Centre website

 

Read more wildlife news stories in BBC Wildlife Magazine

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