Madagascar Freshwater - A Global Ecoregion
One of the world's most distinctive freshwater ecosystems
Snapshot: Ecoregion 162
Size:
590,000 sq. km (230,000 sq. miles)
Habitat type:
Small Rivers
Geographic Location:
Madagascar, an island off the southeast coast of Africa
Conservation Status:
Critical/Endangered
Did You Know!
Volcanoes may die, but they are slow to disappear. When ancient volcanoes on Madagascar exploded or collapsed, they left behind many craters.
These then filled with water to create lakes, some of which still provide habitat for birds and fish. One crater lake named "Tsimanampetsotsa" lies so close to the coast that it contains saltwater.
These then filled with water to create lakes, some of which still provide habitat for birds and fish. One crater lake named "Tsimanampetsotsa" lies so close to the coast that it contains saltwater.
About the Area
Madagascar has one of the most distinctive freshwater ecosystems in the world with many endemic species. The island has an elevated plateau from which short, swift rivers flow over a narrow strip of land as they descend to the Indian Ocean to the east.
To the west, long rivers flow down from the central plateaus across sedimentary beds into the Mozambique Channel. Due to climatic variability throughout the island, the freshwater systems of the east side of the island contrast greatly with those of the west, although they all experience seasonal flooding and high discharges.Local Species
Madagascar has large numbers of endemic fish, aquatic mammals, reptiles, amphibians, gastropods, crustaceans, and although poorly studied - aquatic insects.
The majority of the endemic freshwater fishes of Madagascar are from the Herring (Clupeidae), Sea catfish (Ariidae), Bedotiid (Bedotiidae), Sleeper (Eleotridae), Rivuline (Aplocheilidae), Goby (Gobiidae), and Cichlid (Cichlidae) families. Examples of these fishes are Chonophorus macrorhynchus, Teramulus kienerie, and Rheocles alaotrensis.
Other important endemic species include the aquatic tenrec (Limnogale mergulus) - from a family of insectivorous mammals, the rare turtle - Eretmochelys madagascariensis, a large aquatic lizard (Scelotes astrolabi), a rich community of endemic decapod crustaceans, including six species of Parastacid crayfishes (Astacoides spp.), and many endemic frogs.
In addition, at least twenty species of Atyid shrimps (Caridina spp.), three species of Palaemonid shrimps (Machrobrachiumspp.), and nine species of Patamonid crabs, inhabit the island's rivers and streams.
Threats
The freshwater fishes of Madagascar are considered the island's most endangered vertebrates. Habitat degradation, siltation, temperature increases due to deforestation, agriculture, overfishing, and exotic species are considered the main causes of species decline. Introduced fish species have already replaced many native species in inland lakes and streams.
Resources
• NationalGeographic.com
