Terrestrial and Marine Ecology of Poivre, Amirantes, Seychelles


Terrestrial and Marine Ecology of Poivre, Amirantes, Seychelles

The Amirantes group, Seychelles, comprises 24 islands and islets lying between 5o and 6o south of the equator on the Amirantes Bank, western Indian Ocean. The islands were discovered by the Portuguese navigator Vasco de Gama on his second voyage to India in 1502, soon after acceding to the rank of Admiral, and the islands were subsequently named Ilhas do Almirante or Admiral’s Islands (Lionnet, 1970). The group extends over a distance of 138 km, from African Banks in the north to Desnoeufs in the south. Poivre was visited by the Chevalier du Roslan and named in 1771 by the Chevalier de la Biollière, after Pierre Poivre, former governor of Ile de France (now La Réunion), an agronomist who was instrumental in setting up the spice industry in the Seychelles in the late 1770s. Poivre Atoll lies close to the eastern margin of the Amirantes Bank, in the southern half of the main bank, 15 km southeast of Sand Cay (which is in the centre of the Bank) and 40 km west southwest of the submerged atoll of Desroches. The platform reef consist of two main islands, Poivre island in the north and Ile du Sud in the south, with a large, elongate, shallow lagoon between them and an encircling reef. A third island, Florentin, lies within the western margin of Ile du Sud.

The Percy Sladen Trust Expedition visited Poivre on 9th October 1905. Having crossed the sand-flat from Poivre island to Ile du Sud, expedition members became trapped by the tide and thus had time to fully explore the southern island (Gardiner, 1936). The morphology, soils, ecology and agriculture at Poivre island were documented in the 1960s (Baker, 1963; Piggott, 1969) and a plant list was compiled by S.A. Robertson and F.R. Fosberg following a two day visit to the island by the first author on 26th and 27th October 1976. Robertson found the island in much the same condition as when described by Piggott (1969) but with greater agricultural activity and with cattle and pigs being kept (Robertson and Fosberg, 1983). When Poivre island was visited in 2005, the only agriculture taking place on the island was for subsistence purposes, undertaken by a small number of workers from the Island Development Company (a government parastatal which took over ownership of the island in 1981). A small settlement exists on the eastern tip of Poivre island. In 2005, a hotel development was underway on the island, but progress has been slow. The centre of the island has been bisected by an 1,100 m long airstrip and the existing boat channel is being enlarged to facilitate the entry of larger vessels.

The Netherlands Indian Ocean Programme, onboard the R.V. Tyro, called at Poivre on 29th and 31st December 1992 and 1st January 1993. SCUBA and snorkel surveys were conducted on the north and west reef-slopes of Poivre (van der Land, 1994). A single seabed trawl at a depth of 57 m was conducted using a 3.5 m Agassiz trawl west of Poivre atoll and three baited fishtraps were deployed at a depth of 43 m northwest of Poivre island (van der Land, 1994).

A collaborative expedition between Khaled bin Sultan Living Oceans Foundation, Cambridge Coastal Research Unit and Seychelles Centre for Marine Research and Technology – Marine Parks Authority to the southern Seychelles was conducted onboard M.Y. Golden Shadow, from 10th – 28th January 2005. The primary aim of the expedition was to use a CASI (Compact Airborne Spectrographic Imager) sensor onboard a seaplane to conduct large-scale mapping of the southern Amirantes, Alphonse/St. Francois (Spencer et al., 2009) and Providence Bank. All surveys at Poivre were conducted on 26th and 27th January 2005.