Lake Alaotra NPA (6567)
Madagascar, Africa
Site overview
KBA status: confirmed
Global KBA criteria: A1b, A1e
Year of last assessment: 2018
National site name: NAP Lac Alaotra
Central coordinates: Latitude: -17.5667, Longitude: 48.4333
System: freshwater, terrestrial
Elevation (m): 750 to 790
Area of KBA (km2): 508.78578
Protected area coverage (%): 100.00
KBA classification: Global
Legacy site: Yes
Site details
Site description: This is the largest lake in Madagascar, situated 170 km north-east of Antananarivo and 7 km north of Ambatondrazaka. It lies in a tectonic basin 40 km long and 9.5 km wide, located between the Grand Angavo escarpment in the west and the Mangoro–Alaotra escarpment in the east. Its depth is 1.0–2.5 m during the low-water season and 4 m during the high-water season. The water is fresh, and turbid with suspended silt due to intense erosion of the deforested hills that surround the lake. The lake is fed by the Sasomanga and Sahabe rivers in the south, and by the Sahamaloto and Anony rivers in the north-west. The only drainage river, the Maningory, flows out of the north-eastern part of the lake. The lake-bottom sediments consist of thick layers of sand, black mud and grey clay. Natural, permanent marshes occur along the lake margin, especially in the southern part of the site. The largest are located to the south and east of the Antanamalaza peninsula and in the part drained by the Maningory. There are also wet grasslands. The lake vegetation was formerly dominated by water-lilies Nymphaea, but these have decreased in extent due to competition with non-native water-hyacinth Eichhornia and water-fern Salvinia. In the marshes, sedges Cyperus and reeds Phragmites dominate. Secondary savanna covers the surrounding hills.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs. Alliance for Zero Extinction (2018): site confirmed as an AZE site during the AZE project (2015-2018). Taxonomy, nomenclature and Red List category follow the IUCN 2016 Red List.
Additional biodiversity: See Box and Tables 2 and 3 for key species. Eighty species are known from the site, of which 13 are endemic to Madagascar. Lake Alaotra is an exceptional site for waterbirds. It formerly held two highly threatened endemic species, which were probably confined to the lake, but which may now be extinct: Tachybaptus rufolavatus and Aythya innotata. The former was last recorded in 1985 and the latter in 1991. Furthermore, the flocks of Anas melleri that occur on the lake constitute the largest congregations known for this species, and Ardea humbloti also occurs regularly (in its only eastern site), though it is not proven to have bred. Non-bird biodiversity: Lemur: Hapalemur griseus alaotrensis (CR). Carnivore: Salanoia concolor (VU).
Habitats
Land use: agriculture | fisheries/aquaculture
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Wetlands(Inland) | 100 |
Threats
Summary of threats to biodiversity at KBA: Human activities that pose a threat include the burning of marsh vegetation, poaching, intensive gill-netting, and conversion of marshes to rice-fields. The invasion of the lake by non-native vegetation, and the introduction of non-native fishes such as Tilapia and Ophiocephalus, have resulted in the loss of several native species of fish, waterbird and aquatic plant.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Agriculture & aquaculture | Annual & perennial non-timber crops | Shifting agriculture | Ongoing |
| Agriculture & aquaculture | Livestock farming & ranching | Nomadic grazing | Ongoing |
| Biological resource use | Hunting & collecting terrestrial animals | Motivation Unknown/Unrecorded | Ongoing |
| Biological resource use | Fishing & harvesting aquatic resources | Persecution/control | Ongoing |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |
| Pollution | Agricultural & forestry effluents | Soil erosion, sedimentation | Ongoing |
Additional information
References: Delacour (1930), Hawkins et al. (2000), Nicoll and Langrand (1989), Payne (1960), Pidgeon (1996), Rand (1936), Voous and Payne (1965), Wilmé (1993), World Wide Fund for Nature–Madagascar (1997), Young and Smith (1989).