See Box for key species. In addition, there are occasional records of Falco naumanni, Gallinago media, Glareola nordmanni and Acrocephalus paludicola from this site. All are thought to refer to birds on passage, although the status of A. paludicola is hard to establish. More than 116,000 waterbirds were recorded here in September 1987. Merops bulocki, a species of the Sudan–Guinea Savanna biome (A04), has been recorded at this site.

Lake Aleg is of great importance as a passage and wintering area for migratory birds, especially Palaearctic birds.
Non-bird biodiversity: None known to BirdLife International.

In 2023, the annual count gave a total of 44881 individuals.

In 2022, the total number of birds counted was 179038.

In 2021, the total number of birds counted was 41600.

the 2020 annual count gave a total of 73999 individuals divided into 51 species (Natmau count, 2020)

the dominant species are : Anas querquedula 15400 individuals and Cascaded Duck: 23400 individuals

in January 2017,41600 individuals were counted with 24 different species(den Natmau, 2017).

the dominant species are: Anas querquedula( 12500individuals),Plectropterus gambensis(6500 ind), Dendrocygna viduata(6580) and Himantopus himantopus(7550)

20,8734 individuals divided into 28 species were counted in 2011 by the Direction des Aires Protégées et du Littoral(DAPL).

The dominant species are: Plectropterus gambensis(17500 individuals), Dendrocygne viduata(32700 ind), Himantopus himantopus(13600),Anas querquedula(23800 ind), Porphyrio porphyrio(12000), Bubulcus ibis(9800ind) and Dendrocygne bicolor(9300ind).

The soil and vegetation around the lake are heavily affected by traditional flood recession agriculture, mainly sorghum farming, which covers an area of 2,250 ha of the lake's exposed shores. This includes the construction of makeshift fences around the fields, which create obstacles to the wind, causing sand to accumulate. The construction of small dams, notably on the Oued Ketchi, also reduces the volume of water reaching the lake. The Acacia nilotica woodland that once covered much of the uplands around the lake has now been largely cleared. The fringed herbaceous vegetation is heavily overgrazed by large numbers of domestic animals. Unregulated hunting of waterfowl, particularly by an urban elite from Nouakchott, a three-hour drive (240 km) away, is a growing problem.

The Lac d'Aleg project has been operating in the region for several years. It focused on maximizing the potential of the region's natural resources through small-scale village initiatives: wells, dams and dykes, setting up butane gas sales points, agricultural extension services and so on. This program has been replaced by the PARP project. D'aménagement rural en zone pluviale), financed by the European Union. Its activities will focus on supporting micro-projects, small businesses and local cooperatives, equipping and digging wells, building dams and improving roads/access. The impacts of agricultural development and dam construction must be taken into account.
Decreasing water availability

Lack of integrated ecosystem management

With regard to threats, in the vicinity of Lac d'Aleg, reduced rainfall has led to overgrazing and overexploitation of grazing areas and wetlands. This over-exploitation is particularly evident in the near-total exploitation of the Acacia nilotica forest.
The same applies to ground vegetation: the continuous pressure of grazing animals in the area has caused it to disappear completely.

 

-The only strong measure in this area is the annual counting and monitoring of waterbirds carried out by Nature Mauritanie. The aim is to identify trends in waterbird numbers, detect and act on threats at the right time, and monitor the status of key species and their habitats.