Madagascar’s extremely rich marine biodiversity is higher than that of any other Western Indian Ocean country. It hosts around 15,000 plant species, of which more than 12,000 are endemic, meaning they can be found nowhere else on earth.
The 2012 Agulhas and Somali Current Large Marine Ecosystems (ASCLME) Project states that there are 123 species of sharks and rays present in Madagascar, 31 of which are classified by IUCN as threatened, 1 is endangered (the skate Rostroraja alba), 17 are vulnerable (the whale shark and endemic skate Dipturus crosnieri) and 10 are near-threatened. All three species of sawfishes are classified as “critically endangered” on the IUCN Red List and in Appendix I of CITES.
14 species of marine teleost fish present in Madagascar are listed on the IUCN Red List.
Approximately 40 species of seabirds are found around the coasts of Madagascar, including albatrosses, petrels, phaetons, frigates, boobies and terns.
The island’s key coastal ecosystems include estuaries, mangrove, seagrass beds, coral reefs and offshore ecosystems beyond the continental shelf. The mangrove forests occupy about 327,000 ha and the seagrass beds and coral reefs are found along 1 400 km of the coastline. Madagascar harbours seven seagrass species. Most seagrass beds are dominated by T. ciliatum and Thalassia hemprichii however, information on the seagrasses of Madagascar is limited.
 (UN Environment Programme and WIOMSA, 2015)