Extensive mangrove forests occur on most islands in Seychelles. 4 Sites of international significance (Port Launay, Mare Aux Cochons, La Plain Hollandaise and Aldabra Atoll) have been declared under the RAMSAR Convention. Aldabra Atoll has extensive systems of mangroves that provide feeding and nesting habitats for many seabirds and waders. In Seychelles, all mangroves species are indigenous, having been brought to the islands by the sea. Some species of mangroves are able to act as pioneer species, colonizing new areas of sand and mud which are still unstable, for example Rhizophora (mangliye rouz) and Avicennia (mangliye blan). Other species are found in sheltered areas or along river edges. Other grows towards the landward side of mangroves where sea water only penetrates at very high tides, for example Lumnitzera (mangliye pti fey) and Xylocarpus (mangliye ponm). At the edges of mangroves, on slightly higher land, it is possible for other plant species to grow, but these are usually adapted to wet or marshy conditions or are tolerant of salt, for example fouzer lanmar and patatran. Algae of various types frequently grow as ephiphytes on the aerial roots of mangrove trees, for example on Sonneratia (mangliye fler).
The mangrove is an intertidal habitat. It is often found where a river meets the sea and where the land is sheltered from strong waves, such as in bays or inside a fringing coral reef. The river brings fresh water to the mangrove but at high tide the trees are surrounded by seawater or brackish water (mixture of salt and fresh water). The trees are adapted to the varying salt content of the water and also to the fluctuating tide.
Although mangroves come from several different plant families, they have all developed similar adaptations to life in this intertidal habitat. Mangrove trees are evergreen. Their leaves are thick, leathery and covered with either a waxy cuticle or minute hairs, which reduces water loss from the leaves.
Special aerial roots called pneumatophores develop on most mangrove trees. These can absorb oxygen from the air when the roots are exposed at low tides. This is necessary because the water-logged soil in which the roots grow does not contain much oxygen.