Lake Alaotra ( mg, farihin' Alaotra, ; french: Lac Alaotra) is the largest

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

, located in

Alaotra-Mangoro Region Alaotra-Mangoro is a region in eastern Madagascar. It borders Sofia Region in north, Analanjirofo in northeast, Atsinanana in east, Vakinankaratra in southwest, Analamanga in west and Betsiboka in northwest. The capital of the region is Ambatondra ...

and on the island's northern central plateau. Its basin is composed of shallow freshwater lakes and marshes surrounded by areas of dense vegetation. It forms the center of the island's most important rice-growing region. It is a rich habitat for wildlife, including some rare and endangered species, as well as an important fishing ground. Lake Alaotra and its surrounding

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s cover , and include a range of habitats, including open water, reedbeds, marshes, and

rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...

paddies. The lake itself covers . Lake Alaotra was declared a wetland of international importance under the international

Ramsar Convention The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of Ramsar sites (wetlands). It is also known as the Convention on Wetlands. It i ...

on February 2, 2003. The

longfin tilapia ''Oreochromis macrochir'' (longfin tilapia, greenhead tilapia, or greenhead bream) is a species of cichlid native to the Zambezi Basin, Lake Mweru, and Lake Bangweulu. It has been used extensively for stocking ponds and dams in other parts of s ...

(''Oreochromis macrochir'') was introduced into Lake Alaotra from the mainland in 1954 and proliferated quickly. By 1957, it provided 46% of the catch, perhaps because it was moving into an empty ecological niche as a

phytophagous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

species. The fertile plain surrounding Lake Alaotra is Madagascar's most important rice-producing region. The hills surrounding the lake were formerly forested but have mostly been cleared for farmland in past decades. Severe

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

on these vulnerable hill slopes has caused considerable

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the ...

of the lake, which is fast disappearing; the lake is now only deep during the dry season. Pressure to create more rice fields has also led locals to burn the reedbeds surrounding the lake. These reedbeds provide the sole habitat of the

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Alaotra gentle lemur (''Hapalemur griseus alaotrensis''). The Alaotra gentle lemur is now limited to only of remaining reedbeds, and in recent years, its population rapidly declined by 60%, from about 7,500 individuals in 1994 to 3,000 in 2001, mostly from habitat loss, but also from hunting by local villagers. The lake is the type locality of the butterfly '' Artitropa alaotrana'' and an important but increasingly threatened habitat for

waterbird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...

s, including the endangered

Meller's duck Meller's duck (''Anas melleri'') is a species of the dabbling duck genus ''Anas''. It is endemic to eastern Madagascar. Although a population was established on Mauritius in the mid-18th century, this is on the verge of extinction due to habitat ...

(''Anas melleri''). Two waterbird species were endemic to northern Madagascar, the

Madagascar pochard The Madagascar pochard or Madagascan pochard (''Aythya innotata''; mg, Fotsy maso, Onjo) is an extremely rare diving duck of the genus ''Aythya''. Thought to be extinct in the late 1990s, specimens of the species were rediscovered at Lake Matsa ...

(''Aythya innotata'') and the

Alaotra grebe The Alaotra grebe (''Tachybaptus rufolavatus''), also known as Delacour's little grebe or rusty grebe, is an extinct grebe that was endemic to Lake Alaotra and its surrounding lakes in Madagascar. Description The grebe was about long. Its abili ...

(''Tachybaptus rufolavatus''). The Madagascar pochard is now critically endangered and no longer found on the lake, although very small numbers exist elsewhere. The Alaotra grebe was declared extinct in 2010. The area of the lake may have been its only habitat.Lake Alaotra
at ''

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

'' The Ambato River provides the lake with water and also drains it. After 381 km, the river flows into the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

References

External links

The GRAP-Lake Alaotra project

* ttp://www.mwc-info.net Project Alaotra by Madagascar Wildlife Conservation {{DEFAULTSORT:Alaotra, Lake Lakes of Madagascar Ramsar sites in Madagascar Toamasina Province Rift lakes Important Bird Areas of Madagascar