Holding onto hope: long-term coral reef monitoring in southern Seychelles

To continue the long-term surveys of the coral reefs of four remote coral islands in the southern Seychelles and to discover how quickly reefs can recover from stressful events such as coral bleaching and cyclone damage.

Coral reefs face worldwide existential threats from human activity. Aldabra, the largest raised atoll in the Indian Ocean, is fully protected from direct human influence. It is one of the last remaining pristine coral reef ecosystems in the world. Neighbouring reefs at Assomption, Astove and St Pierre islands also help to maintain the high biodiversity supporting the reefs of the southern Seychelles. This project will continue to provide the long-term data needed to help in their conservation.

‘Once on shore, Wright and I ran around like lunatics, mapping and collecting. It was immediately apparent that Aldabra was one of the most remarkable islands on earth.’ These words were written by the late Dr David Stoddart, whose love affair with Aldabra began in 1966. He even named his daughter Aldabra! Stoddart was instrumental in helping save Aldabra from becoming a military base. Instead the Royal Society set up a research station on the atoll and it became one of the most protected areas in the Indian Ocean. Most of the ecological and geological work there focused on the terrestrial environment. Marine science and coral reef activities followed, but they were specific projects that were short-term and limited to the atoll. When I and my co-workers established the Aldabra Marine Programme (AMP) in 1999 after a severe coral bleaching event in the region, we realised that understanding the recovery of the coral reefs in the southern Seychelles from this significant coral kill required a long-term study that included other locations in the region. Over the following 10 years AMP returned to the southern Seychelles region seven times, conducting surveys in the Aldabra Group at Aldabra Atoll, Assomption and Astove islands and in the Farquhar Group at St Pierre Island. These AMP regional surveys came to an abrupt halt after December 2008 due to piracy in the region. We now plan to resume our surveys at the original locations we set up in 1999. Much has happened in the intervening years, including several new bleaching episodes, and this gives us a unique opportunity to continue working as the same team and to build on the substantial database that we began at the turn of the century.

The general aim is to provide long-term data on the changes to the coral reefs and reef fish community at Aldabra Atoll, Assomption, Astove and St Pierre islands using the same research team and same methodologies established in 1999. The first objective will be to relocate each of the permanent underwater survey sites on the outer reef of each island. They are marked by lead core survey lines, which by now will be well encrusted with coral and are likely to need replacing. Secondly, we will resurvey the sites using the exact same methods as before. Employing the same team of scientists will give us a very high level of consistency. Finally, we will locate and replace the underwater temperature probes (thermometers) that we left in 2008. Their batteries will have expired after several years, but we expect to be able to retrieve the data. We will then deploy new sets of temperature probes, setting them to record temperatures continuously every hour.