Current view: Text account
Site description (2001 baseline):
Site location and context
Rkîz is situated approximately 90 km north-east of the town of Rosso. It is a depression 34 km long and 4–6 km wide aligned north-east–south-west. It is filled by water from the Senegal river and, to a lesser extent, from run-off due to rainfall. Two swamps, the Nasio and the Laouwaya, join Rkîz to the river system. The eastern part of the lake is 3 m below sea-level and the western 2 m below. The lake has dried out completely in drought years. The construction of a dam in the Laouwaya, as well as a dyke at Nasio, has limited the natural filling of the lake and reduced the area of the lake to 6,100 ha. The whole area is now managed by a system of dams and dykes for the cultivation of rice.
The transformation of the lake into an agricultural zone has led to the loss of most of the original vegetation. The northern part of the lake remains the most species-rich. It is dominated by
Cassia tora, with
Nymphaea sp
.,
Mimosa pigra,
Indigofera oblongifolia,
Echinochloa pyramidalis and
Aeschynomene sp. The banks are typically covered with grasses such as
Cynodon dactylon,
Dactyloctenium and
Eragrostis spp. Elsewhere, remaining trees include
Acacia raddiana and
A. senegal as well as
Leptadenia pyrotechnica. Following clearance for agriculture
Calotropis procera has colonized much of the area and is now the dominant ligneous species. In the south-west there are some saline soils with
Tamarix senegalensis. In the south-east, where the oueds lead to Nasio and Laouwaya, some stands of
Acacia nilotica still persist, due to seasonal flooding via the rice-fields.
The number of birds present at this site is largely dependent on rainfall and on the quantity of river water allowed in through the dykes. Other counts have included 1,800
Limosa limosa and 410
Plectropterus gambensis in 1987, while in November 1999 an aerial survey recorded 43,600 waterbirds.
Non-bird biodiversity: Crocodylus niloticus and Hippopotamus amphibius are reported to be present in the area; both are nationally threatened.
Pressure/threats to key biodiversity
The traditional multi-use management systems, which included flood-recession cultivation of sorghum and livestock-rearing, have been replaced by more intensive agricultural systems. Although levels of rice production at Rkîz are higher than along the Senegal river (1.9 versus 1.5 tonnes/ha/year), this does not compensate for the loss of pastureland and livestock production. In fact, the expansion and intensification of agriculture has been to the detriment of the animal herding in the area. Conflicts between farmers and herders have increased, fishing is seriously affected as water-levels are too low, the water is increasingly polluted by fertilizers and pesticides, while felling of the
Acacia nilotica woodland for fuel- and construction-wood and to clear land for agriculture has significantly reduced habitat suitable for tree-roosting species such as
Nycticorax nycticorax. Only a few roosting sites remain today.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Rkîz (Mauritania). Downloaded from
https://datazone.birdlife.org/site/factsheet/rkîz-iba-mauritania on 23/11/2024.
