 |
THE
FRENCH CORAL REEF SOCIETY
|
|
|
|
|
Area of Operation NEW CALEDONIA Major reef features New Caledonia extends over more than 400 km from North West to South East between 20° and 22°30' South of latitude and 164°30' and 167°30 East of longitude. The narrow and mountainous island is encircled by barrier reefs, the total surface area of which is 8000 km2. The coral reefs extend far away from the island to the North West and the South East, up to the Entrecasteaux Reefs and the Island of Pines, respectively. It is therefore a reef system of considerable importance, second only to the Great Barrier Reef, with an extensive lagoon development (total lagoon surface area is approximately 24,000 km2). Within the lagoon, which can be up to 30 km wide and 80 m deep, platform-type reefs are found, often with sand cays (the "lagoon islets") which may be vegetated with either grass, shrubs or trees.
It is only in the central part of the south-west coast that the reef loses its characteristic barrier appearance and becomes a fringing reef, with a very shallow lagoon or small boat channel. Narrower fringing reefs are also found within the lagoon along some parts of the coastline, including in very sheltered bays, such as the Baie de Prony. Lastly, in the south-east lagoon, elements of a double barrier reef, a particularly rare physiographic reef type, are observed.
Three types of soft bottom communities are found on the lagoon floor, as a function of the nature of the sediment : (1) a white sand community in sediments of reefal origin (high carbonate content) stretching along the backreef, in the outer part of the lagoon, (2) a grey sand community in sediments of mixed origin (terrigenous and organogenic) extending over a large median strip covering most of the lagoon floor, and (3) a muddy sediment community, colonizing terrigenous sandy mud or mud deposits present along the shoreline and in all embayments (where muddy deposits can be very thick). East of New Caledonia, the Loyalty Archipelago is composed of 3 main islands (Maré, Lifou and Ouvea) and includes the Beautemps-Beaupré and Astrolabe reefs, towards the North West. These islands (as well as Walpole, to the South East) are of reefal origin and are low and flat, with a maximum altitude decreasing from the South East (129 m at Maré) to the North West (Ouvea is a partly submerged atoll). On Maré and Lifou, only narrow and discontinuous fringing reefs are present. To the West of New Caledonia one finds first the submerged atolls of Fairway and Lansdowne and further West, the atolls - also largely submerged - of Chesterfield and Bellona. The coral reefs of New Caledonia and dependancies are characterized by a high species diversity, both for hard substrate and soft substrate communities. This high diversity results from the fact that New Caledonia is, from a biogeographic standpoint, close to the Indo-Pacific centre of maximum diversity, but also from a high diversity of types of environments and niches.
Principal institutions and activities of ACOR members IRD (ex ORSTOM) BP A 5 Nouméa. Université Française du Pacifique Basic references Fromaget M. & Richer de Forges B. 1992. Catalogue bibliographique indexé du milieu marin de Nouvelle Calédonie. (2eme édition). Nouméa, ORSTOM, 274 p. Kulbicki M. 1997. Bilan de 10 ans de recherche (1985-1995) par l'ORSTOM sur la diversité, la densité, la biomasse et la structure trophique des comunautés de poissons lagonaires et récifaux en Nouvelle-Calédonie. Cybium, 21 (1) suppl. 47-79. Kulbicki M. & Rivaton J. 1997. Inventaire et biogéographie des poissons lagonaires et récifaux de Nouvelle-Calédonie. Cybium, 21 (1) suppl. 81-98. Richer de Forges, B. 1991. Les fonds meubles de Nouvelle Calédonie : généralités et échantillonnages par dragages. Le benthos des fonds meubles des lagons de Nouvelle-Calédonie : Vol 1. ORSTOM, Etudes et Thèses, 7-148.
|
