The Third Coral Bleaching Event; how our corals have fared

By Annie Vidot and Georgina Beresford

IMG_3827Coral reefs are the rainforests of the sea with a rich biodiversity providing homes for thousands of fish and other marine organisms. It also plays an important role in our country’s economy as it relies on its diverse resources; the economic value of coral reefs has been estimated at $29 billion a year. Thus the future health of coral reefs will have a large effect on the future economic resources and biodiversity of the planet.

Here in Seychelles at Petite Anse, Mahé, our coral reef and coral nursery is under threat from coral bleaching. These warm water conditions makes it hard for our coral fragments to grow properly therefore, in the face of extensive coral bleaching we decided to make a plan and think about different methods that could be applied in the water to reduce stress and increase our coral fragments’ chances of survival.

Recovering fragment

Recovering fragment

Bleaching Acropora fragment

Bleaching Acropora fragment

Lots of ideas popped-up in our minds. Our first plan of action was to stop all additions to our coral nursery during the high temperatures, so as not to cause any more unnecessary stress to the corals. The second was to help protect them from the intense UV by providing shade for the corals; so we covered two patches in the nursery, by suspending a fine net over them with the idea of reducing the light intensity reaching the corals. This worked well to begin with and the fragments under the shade showed less signs of bleaching than those exposed. Sadly, the weather was against us. The storms that hit Mahé in May and June meant we had to remove the netting for long periods of time– so nature kicked us a little!

Photo 09-04-2016, 05 49 51

The deep nursery

Another important factor we considered was how to reduce the light intensity and water temperature around our coral fragments. We decided to move a portion of our corals into a deeper nursery. Planning how to create a deep nursery was an exciting task. We thought about a different strategy, learning from our trials, our shallow nursery netting and how to make it more effective, especially during storms. We decided to hang our corals on lines of wire secured between boulders in the deeper reef, giving these fragments a new home which should offer more resilience to any surge caused by storms and potentially giving the corals the ability to withstand the bleaching event in cooler, deeper water. Luckily, a couple of months later the strategy turned out to be relatively successful; some of our corals were bleached, but they have a higher chance of recovering in the deeper water, they have experienced stormy conditions and are still hanging attracting small fish to their surroundings!
IMG_4448Our shallow reef and nursery have been badly affected during the coral bleaching like other reefs across Seychelles and the tropics, but now that the temperature has cooled down we can see some corals recovering on both on the reef and in the nursery, we’ve also spotted a few new coral colonies that have settles in the shallow reef– that’s exciting news which gives us hope!