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April 9, 2009

Réunion’s Bleached Reefs

Oceana Wavemaker Rachel Allen is currently living la vie en rose on the French Island of Réunion in the middle of the Indian Ocean, east of Madagascar. (You jealous yet?) She wrote to us about her experience monitoring the area’s coral reefs, many of which are bleached. Coral bleaching, which is happening around the world, is often caused by higher than normal sea temperatures. (See our Q&A with coral reef scientist J.E.N. Veron for more on the state of the world’s reefs.) Anyway, here’s Rachel:

It’s absolutely incredible to live on a tropical volcanic island, but all is not as idyllic as it seems at a glance. The coral reefs here are slowly submitting to the developments of human inhabitants.Luckily, I’ve come across a local association, La Vie Oceane, that is working to monitor and protect the marine environment and the coral reefs. They are helping ARVAM (Agence pour la Recherche et la Valorisation Marine), a marine research and protection organization on La Réunion, with a local chapter of Reef Check, an international standard procedure for educating the public about reefs and monitoring their health.About a month ago, I joined them for their first outing on the west coast of La Reunion, at Trou d’Eau. All of us volunteers put on our masks and snorkels, and flippered out to the buoys. With a handy fish guide and underwater marking sheet, my team of three divided up our 8 families of fish, and counted all the ones we could find along four 20-meter segments. I had the surgeonfishes and the groupers. The other volunteers worked alongside us on invertebrates and benthos.The site we looked at is mostly made up of acropora corals, which are algae-covered near their bases, and white or recently dead, due to coral bleaching, on the top parts. In their healthy state, these corals serve as the breeding ground for the calyxs of green algae. Altogether, about 80 percent of the upper parts of the acroporas have recently died due to the bleaching phenomenon that has been touching the island’s reef since the beginning of the year. The next study on this site, which will come in the winter months (June to October) or next year, will enable the group to determine the longer term affects of this phenomenon, and how the marine life is coping. If you read French, you can check out the report at http://reefcheck.fr/spip.php?article52.Thanks to la Vie Oceane and ARVAM for getting me and other volunteers involved, and turning a Saturday morning at the beach into scientifically rigorous montitoring project!