Lake Itasy also known as Itasianaka is a lake in central Madagascar. It is located in Itasy Region. It is situated in the municipalities of Ampefy, Soavinandriana, Manazary and Analavory. Lake Itasy has an area of 3,500 hectares. It is the fourth largest lake on Madagascar, after lakes Alaotra, Kinkony, and Ihotry.Battistini, R., Richard-Vindard, G. (eds) (1972) ''Biogeography and Ecology in Madagascar''. Monographiae Biologicae, vol 21. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-7159-3_5 The lake has an average depth of 4 meters, and reaches up to 10 meters deep. The water level varies seasonally. There are marshy areas in the southern and eastern parts of the lake.BirdLife International (2023
Bird Areas factsheet: Lake Itasy
Accessed 16 January 2023. Lake Itasy lies east of the Itasy volcanic field. The volcanic activity in the region is relatively recent, and the lake was formed when lava flows blocked a river, forming a lake behind it. The landscape around the lake is covered with Strombolian

scoria cone A cinder cone or scoria cone is a steep, conical landform of loose pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or l ...

s and

trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanite, aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrus ...

domes. The volcanic landscape around the lake has many smaller lakes (

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s) and peat bogs. The Andranomena and Mariandrano rivers empty into the lake from the east. The Lily River is the lake's outflow, draining westwards from the northwestern corner of the lake. The Lily is a tributary of the Sakay River, which is a tributary of the

Tsiribihina River The Tsiribihina is a river of western Madagascar. The main tributaries are the Mahajilo, Manandaza, Mania, and Sakeny rivers. Its basin has an area of 49,800 km2. 7,025 km2 is in the basin of the Sakeny River, 14,500 km2 in that of the Mahaj ...

. The Tsiribihina flows westwards to empty into the

Mozambique Channel The Mozambique Channel (, , ) is an arm of the Indian Ocean located between the Southeast African countries of Madagascar and Mozambique. The channel is about long and across at its narrowest point, and reaches a depth of about off the coa ...

Flora and fauna

There are reedbeds along the edges of the lake, composed mostly of species of the reed ''

Phragmites ''Phragmites'' () is a genus of four species of large perennial plant, perennial reed (plant), reed Poaceae, grasses found in wetlands throughout temperate and tropical regions of the world. Taxonomy The World Checklist of Selected Plant Famili ...

'' and the sedge ''

Cyperus ''Cyperus'' is a large genus of about 700 species of sedges, distributed throughout all continents in both tropical and temperate regions. Description They are annual or perennial plants, mostly aquatic and growing in still or slow-moving ...

'', which grow up to two meters high. There are also floating mats of the non-native water-hyacinth ''

Eichhornia ''Eichhornia'', commonly called water hyacinths, was a polyphyletic genus of the aquatic flowering plants family Pontederiaceae. Since it was consistently recovered in three independent lineages, it has been sunk into '' Pontederia'', together ...

''. 44 species of birds have been observed at the lake, including ten Madagascar endemic species. Native birds include

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''), Madagascar grebe (''Tachybaptus pelzelnii''), Madagascar flufftail (''Sarothrura insularis''), Madagascar pond heron (''Ardeola idae''), Madagascar snipe (''Gallinago macrodactyla''), and Madagascar marsh harrier (''Circus macrosceles''). The lake is designated an

Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Int ...

. The environment of the lake and its tributary rivers have been altered by pollution, erosion and siltation, habitat destruction, and the introduction of

exotic species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

. The native fish '' Ptychochromoides itasy'', last observed in the lake in the 1970s, was thought extinct until a population was discovered in the Sakay River.Ravelomanana, T. & Sparks, J.S. 2020. ''Ptychochromoides itasy'' (amended version of 2016 assessment). The

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

2020: e.T44513A177066939. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T44513A177066939.en. Accessed 17 January 2023.

References

{{Authority control Itasy Itasy Region Tsiribihina River Important Bird Areas of Madagascar Itasy