News from Eden Island

SEYCHELLIAN REEF RELOCATION THE BIGGEST AND MOST SUCCESSFUL TO DATE

The 56ha Eden Island residential marina and mixed use development in the Seychelles is beginning to achieve widespread recognition among marine biologists and ecologists for a variety of groundbreaking achievements – but foremost among these will probably always be the largest and most successful reef relocation yet attempted in the Seychelles.

The reef relocation preceded and was an essential part of the project – and it has, say the consulting ecologists, set a new benchmark in development for areas with coral reefs.

Craig Heeger, CEO of the Eden Island development company, explained that in 2002 the Seychelles government decided to make more land available for development – with the aim of reducing development pressures on Mahe itself and of raising the low living standards of the majority of the Seychellian people.

The creation of Eden Island has been an important part of the macro-plan. The island, which was bought by the current development consortium in 2004, is based on a coral reef just 300 metres north of Mahe to which it is now linked by a bridge. The island was protected by an armoured revetment of quarried granite rock rising 2,5 metres above sea level.

The reclamation, using dredged coral materials, has resulted in the original island being extended 8ha to a size of 56ha. The design includes a series of small bays which will enable residents to have water on two sides of their homes and to moor their boats close to their homes.

In 2006 a marine ecology study was carried out by the Eden Island developers in conjunction with the Seychelles government. This revealed that the coral reef in the areas likely to be affected was in a relatively healthy condition with more coral cover then is found in many of Seychelles inner islands. (These have often been severely damaged by the so-called bleaching which was caused by excessive exposure to ultraviolet rays in 1998.) The Eden Island reefs also, it was found, had a greater biodiversity, i.e. host a greater range of marine life than most local reefs.

The ecologists, therefore, recommended that at least 60% of the large reef should be relocated to other reef sites, i.e. from the south east to just north of Eden Island.

It was realised early on that the relocation could enable the developers to establish a snorkel trail with underwater information boards at the north east reef – and this will be done.

The ecologists have stressed that the success of the exercise is due in part to previously published studies by other scientists, commissioned in recent years to find ways of rehabilitating reefs damaged by ship grounding, sewage, warm effluent and pollutants, red tides, Crown Thorn invasion, dynamite fishing, coral quarrying, tourist invasion – and land reclamation.

These studies, now confirmed by the Eden Island team, showed that, provided the conditions in the new habitat (e.g. depth and movement of water, temperatures, light penetration and sedimentation levels) are similar to those of the original site, coral translocations can be completely successful.

In this case the ecologists’ confidence was boosted not just by the similarity of conditions at the donor and recipient sites but also by the presence in both areas of the same coral species.

The actual physical relocation was carried out by a team of eight divers with two boats, each usually making three trips and each moving 50 to 150 coral colonies per day so that eventually 2 500 to 3 000 colonies were moved altogether.

The reefs were gently crowbarred off their host sites and then quickly placed in buckets of sea water, care being taken to ensure that no coral was out of the water for more than five seconds. Once in the buckets the coral was covered with tarpaulins to reduce exposure to sunlight and the risk of bleaching. Corals already stressed by bleaching were not used as these, it was found, had less chance of surviving the move.

Epoxy glue was used to secure the corals to the sea floor. This hardened within three hours. The divers used plastic ties and existing holes and crevices to prevent translocated reefs toppling.

The survey now in process has already indicated that the north east reef is recruiting new coral life (especially Aurora Fungia and Porites) very successfully and has achieved a satisfactory level of diversity with 13 genera from eight families represented.

Craig Heeger has said that the professionalism with which this exercise has been backed will be complemented by similar conservation measures on the island which, he said, is destined to be an Indian Ocean resort “second to none”.

Article by: www.edenisland.sc