Lake Tsimanampetsotsa () (also called Lake Tsimanampesotse) is a moderately

alkaline lake A soda lake or alkaline lake is a lake on the strongly basic side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (and related salt complexe ...

in the

Toliara Province The Toliara Province (formerly Toliary or Tuléar) is a former province of Madagascar with an area of . It had a population of 2,229,550 (July, 2001). Its capital was Toliara. Near Toliara was the " spiny forest". Toliara Province bordered the foll ...

, in the southwestern part of

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. It is located at around . The

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

is protected within

Tsimanampetsotsa National Park Tsimanampetsotsa National Park also spelt Tsimanampetsotse, and known as Tsimanampetsotsa Nature Reserve is a 432 km2 national park on the south-west coast of Madagascar in the region Atsimo-Andrefana. The park is south of Toliara and south ...

and it is also within a Ramsar site. The

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

Malagasy means "lake without

dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...

s". It is a sacred place for worship, ceremonies and rituals. Local taboos prevent water pollution. Swimming and the utilisation of pirogues is prohibited. Water, mud and some plants from the lake are used in traditional medicine (Tahirindraza and Marikandia 2015).Rasoloariniaina, JR. 2017. Physico-chemical water characteristics and aquatic macroinvertebrates of Lake Tsimanampesotse, south-western Madagascar. African Journal of Aquatic Science. 42. 191-199. 10.2989/16085914.2017.1357532. The lake is about 20 km long, about 2 km wide and is quite shallow (maximum depth about 2 m). It is situated in a collapse area of the Mahfaly Plateau, in a closed evaporite basin with cliffs of Eocene marine limestone to the east and a wide strip of alluvium, capping low outcrops of limestone to the west.Loewen, M. A., Samonds, K. E., and Ramarolahy, M. F. 2001. Lake Tsimanampetsotsa, A Modern Alkaline Playa Lake In Madagascar.

The Geological Society of America The Geological Society of America (GSA) is a nonprofit organization dedicated to the advancement of the geosciences. History The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitch ...

(GSA), Annual Meeting, November 5–8, 2001. The area is covered by sand deposits of recent and Quaternary origin. In pre-history, there was a paleolake here complete with overland drainage (deltaic sediments laid down by a paleodrainage system have been found). The paleolake was much greater in size and depth, as evidenced by strand lines that ring the outer edges of the basin. The water is “sodic”, highly mineralised and moderately alkaline (pH ~ 8.0) with relatively high concentrations of ammonia and phosphate. Salt concentrations approach that found in seawater, becoming somewhat diluted during the rainy season. The lake may be directly connected to the sea, but this is a matter of conjecture that has not been verified. The eastern part of the lake receives some freshwater flow and so has consistently lower salt concentrations than the western part. The basin is shallow resulting in dramatic variation in the surface area of the lake with even small changes in water level. Water levels can drop significantly during the dry season, resulting in a broad exposed area of seasonal hypersaline flats around a shrunken lake.

Climate and Hydrology

Lake Tsimanampetsotsa is in an area with a semi-arid climate; daytime temperatures are high and precipitation low. It is in the lowest precipitation region in Madagascar, receiving only 300 mm of rain per year. In addition, rainfall amount and location is highly unpredictable; rain often falls only locally. There are no surface rivers here and the lake has no inlet or outlet. Lake levels are tied to rainfall, along with some underground flow from aquifers located further inland. There is a network of groundwater that surfaces at the foot of the Mahfaly Plateau, with three permanent springs (Mande, Andranonaomby and Manava) and numerous seeps and intermittent springs. Lake levels rise with sufficient rainfall, and drop when water evaporates faster than it is being replenished. Dry forest on sandy soils

Vegetation

Emergent plant species able to grow in the sodic water include southern cattail (''

Typha domingensis ''Typha domingensis'', known commonly as southern cattail or cumbungi, is a perennial herbaceous plant of the genus ''Typha''. Distribution and habitat It is found throughout temperate and tropical regions worldwide. It is sometimes found as a ...

'') and flat-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 ...

'' spp.). Glasswort ('' Salicornia pachystachya'') is one of the few species that can tolerate extreme salinity, so it is usually found alone on highly saline sites. Other salt-tolerant species move onto the flats as the water levels recede including ''

Salsola ''Salsola'' is a genus of the subfamily Salsoloideae in the family Amaranthaceae. The genus ''sensu stricto'' is distributed in Australia, central and southwestern Asia, North Africa, and the Mediterranean. Common names of various members of this ...

littoralis, Atripex perrieri'', as well as some grasses (''

Sporobolus virginicus ''Sporobolus virginicus'', known by numerous common names including seashore dropseed, marine couch, sand couch, salt couch grass, saltwater couch, coastal rat-tail grass, and nioaka, is a species of Poaceae, grass with a wide distribution. Desc ...

Paspalum vaginatum ''Paspalum vaginatum'' is a species of grass known by many names, including seashore paspalum, biscuit grass, saltwater couch, silt grass, and swamp couch.Acrostichum aureum ''Acrostichum'' is a fern genus in the Parkerioideae subfamily of the Pteridaceae. It was one of the original pteridophyte genera delineated by Linnaeus. It was originally drawn very broadly, including all ferns that had sori apparently "acro ...

''). The introduced species beach sheoak (''

Casuarina equisetifolia ''Casuarina equisetifolia'', commonly known as coastal she-oak, horsetail she-oak, ironwood, beach sheoak, beach casuarina, whistling tree or Australian pine is a species of flowering plant in the family Casuarinaceae and is native to Australia, ...

'') can be found in small stands along the east shore.

Aquatic Fauna

High phosphate concentrations, originating from erosion, are thought to be the main factor limiting the diversity of aquatic fauna. There are no fish. Invertebrates belonging to four taxonomic groups (Annelida, Gastropoda, Crustacea and Insecta) have been documented. Taxonomic richness was at its highest (15 taxa) in April (rainy season) and decreased to 11 taxa in August (dry season). The eastern part of the lake had consistently more species then the western part, probably because of the consistently lower salt concentrations. The crustaceans were the most widespread species. The aquatic fauna documented in Lake Tsimanampetsotsa is as follows: * Annelida (ringed or segmented worms), family

Glossiphoniidae Glossiphoniidae are a family of freshwater proboscis-bearing leeches. These leeches are generally flattened, and have a poorly defined anterior sucker. Most suck the blood of freshwater vertebrates like amphibians, crocodilians and aquatic tur ...

(freshwater jawless leeches). * Gastropoda species (snails and slugs): '' Planorbis planorbis'' (Planorbidae) (ram's horn snails), '' Georissa petiti'' (Hydrocanidae) and ''

Potamopyrgus ''Potamopyrgus'' is a genus of minute freshwater snails with an operculum, aquatic gastropod molluscs or micromolluscs in the family Tateidae.Bouchet, P.; Rosenberg, G. (2014); Criscione and Ponder 2013. ''Potamopyrgus'' Stimpson, 1865. Accessed ...

'' sp. (Hydrobiidae) (mud snails). * Crustacea species (crustaceans): '' Grandidierella mahafalensis'' (Aoridae) and '' Halmyrapseudes thaumastocheles'' (Apseudidae). Insects found included: flies (Diptera); beetles, including nymph of the

Dytiscidae The Dytiscidae, from the Ancient Greek word δυτικός (''dystikos''), meaning "able to dive", are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species l ...

(diving beetles) and adults of the

Hydroptilidae The Hydroptilidae are a large family of caddisflies (Trichoptera) with a worldwide distribution. They are commonly known as microcaddisflies or purse-case caddisflies, in reference to two characteristic traits of this family: Hydroptilidae are ...

and

Elmidae Elmidae, commonly known as riffle beetles, is a family of beetles in the superfamily Byrrhoidea described by John Curtis in 1830. Both adults and larvae are usually aquatic, living under rocks in fast-flowing shallow areas of streams, such as ...

families; mayflies ( Ephemeroptera); bugs (Hemiptera) from 3 families (

Naucoridae Naucoridae is a small family of insects commonly known as the creeping water bugs and saucer bugs. They are similar in appearance and behavior to Belostomatidae (giant water bugs), but considerably smaller, at long. Naucoridae are found around th ...

Veliidae Veliidae is a family (biology), family of gregarious predatory insects in the suborder Heteroptera. They are commonly known as riffle bugs, small water striders, or broad-shouldered water striders because the segment immediately behind the head ...

and

Notonectidae Notonectidae is a Cosmopolitan distribution, cosmopolitan family of aquatic insects in the order Hemiptera, commonly called backswimmers because they swim "upside down" (inverted). They are all predators and typically range from in length. They ...

); dragonflies of the

Libellulidae The chasers, darters, skimmers, and perchers and their relatives form the Libellulidae, the largest family of dragonflies. It is sometimes considered to contain the Corduliidae as the subfamily Corduliinae and the Macromiidae as the subfamily M ...

family and damselflies of the

Coenagrionidae Coenagrionidae is a family of damselflies, also known as pond damselflies, in the order Odonata and the suborder Zygoptera. The Zygoptera are the damselflies, which although less known than the dragonflies, are no less common. More than 1,300 spec ...

family.

Birds

More than 34 bird species are recorded from the lake area. Greater flamingos (''

Phoenicopterus roseus The greater flamingo (''Phoenicopterus roseus'') is the most widespread and largest species of the flamingo family. Common in the Old World, they are found in Northern (coastal) and Sub-Saharan Africa, the Indian Subcontinent (south of the Hima ...

'') are at times present in large numbers and nest on the lake. Lesser flamingos ('' Phoenicopterus minor'') have also been seen here. The lake and saline flats constitute an important habitat for many threatened water bird species, such as Madagascan plover ('' Charadrius thoracicus'') (VU) and supports a breeding colony of Madagascan grebe ('' Tachybaptus pelzelnii'') (EN).

Towns and villages

* Antanandranto

References

{{Authority control

Tsimanampetsotsa Lake Tsimanampetsotsa () (also called Lake Tsimanampesotse) is a moderately Soda lake, alkaline lake in the Toliara Province, in the southwestern part of Madagascar. It is located at around . The lake is protected within Tsimanampetsotsa Nationa ...

Ramsar sites in Madagascar

Atsimo-Andrefana