Mangroves in Mauritius

The word mangrove dates as far back as 1613 and is considered to consist of the Portuguese word “mangue” meaning fen and the English word “grove”. They are trees that grow in the region between the land and the sea and thus have characteristics of both environments. These trees are found mostly in the tropical and subtropical areas. Over time, they have developed special adaptations to survive in this harsh ecosystem such as extensive and prominent root systems to maximize gaseous exchange.

Among the 54-70 mangrove species that occur worldwide, only two species are found in Mauritius namely Bruguiera gymnorrhiza and Rhizophora mucronata both being in the Rhizophoraceae Family (common name: Red Mangrove). Distributed mostly on the eastern coast of the island (especially at Trou d’Eau Douce, Pointe d’Esny, Poste Lafayette, Poste de Flacq and other islets such as Illot Brocus and Ile aux cerfs), mangrove coverage has been estimated to be around 20 km2 in 2003. R.mucronata is the dominant species while B. Gymnorhiza is less common and has been observed in the brackish water regions at Pointe Lafayette, Ferney, Trou d’eau Douce and Mahebourg.

In certain areas such as Maconde, the mangrove forests are quite thick with the roots protruding at strange places making the journey from the landward region to the seaward side or vice versa a difficult one; in other areas, the mangrove tree coverage is quite sparse. Contrary to mangroves in other areas of the world, the mangrove forests in Mauritius do not harbour dangerous animals like alligators and tigers. The worst you can come across are stray cats and dogs, birds, numerous insects like huge spiders and mosquitoes and marine organisms especially crabs. Mangrove trees are very important elements of the coastal environment. They protect the coast against wave action which otherwise would lead to erosion. The mangrove roots trap sediment thus acting as barriers for marine life upstream such as coral reefs which require clear water to grow. The forest floor provides food to marine organisms in the form of detritus; the mangrove sediment itself is primordial in trapping pollutants. Very important is the fact that mangrove forests act as nurseries for organisms in the juvenile state; in the past, removal of mangroves led to a considerable decline in the fish yield because juveniles were easily eaten by other preys.

Large expanses of mangroves have been cleared on the island in the name of development. About 70% of commercial fishes depend on mangrove sites during their juvenile stages, so healthy mangroves are vital as many people in Mauritius depend on fisheries (fishing, crab catching) to earn a living. In this respect, the Ministry of Fisheries started a mangrove propagation program in 1995 so as to protect and restore the denuded areas. Much of the swamps have thus been saved and today mangrove propagation programs are encouraged throughout the island.