Merja Zerga is a tidal lagoon located 70 km north of Kenitra on the Atlantic coast. The outlet to the ocean lies at the seaside resort and fishing village of Moulay Bou Selham: hence the site’s alternative name of Lagune de Moulay Bou Selham. In addition to its tidal inflow, the lagoon receives fresh water from the Oued Drader and the underlying water-table, which is very close to the surface here. The lagoon itself covers 4,500 ha, of which 30% is open water, and has an average depth of 1.5 m. Large mudbanks are exposed at low tide, providing extensive feeding areas for waders and waterfowl. Around the lagoon and included within the limits of the IBA are areas of rough pasture and marshland, and the Dayet Roureg, a freshwater pond. Vegetation consists mainly of salt-tolerant plants and shrubs such as Spartina sp., Sarcocornia perennis and Juncus rigidus. The annual rainfall of 600–700 mm, coupled with the low-lying nature of most of the site, result in the inundation in winter of large areas of land surrounding the lagoon proper.
See Box for key species. Merja Zerga is internationally renowned as a passage and wintering site for Palearctic migrants, and is without doubt the most important wetland site in Morocco. In total, over 100 species of bird regularly use Merja Zerga. An average of 15,000–30,000 ducks of 11 different species overwinter, as do approximately the same number of mixed Fulica atra and F. cristata. The lagoon also regularly holds 50,000–100,000 waders (19 regular species) and 1,000–2,000 Phoenicopterus ruber. Numenius tenuirostris was last recorded in 1995. There are also many resident breeding species including Asio capensis.
Non-bird biodiversity: Three endemic Moroccan lizards occur: Acanthodactylus lineomaculatus, Chalcides mionecton and C. pseudostriatus.
Pressure/threats to key biodiversity
The lagoon of Merja Zerga was classified as a Permanent Biological Reserve in 1978, and nominated as a Ramsar Site in 1980. It is a priority 1 SIBE (No. L16). Publicly owned, the site is managed by several government agencies: Ministères de l’Agriculture, des Pêches Maritimes, des Habous and de l’Intérieur. A hunting concession is located on the boundaries of the IBA at Merja Kahla. Human activities include fishing, harvesting of shellfish, livestock-rearing, hunting and tourism (including birdwatching). Threats include illegal poaching and egg-collecting, over-fishing and overgrazing, excessive exploitation of groundwater for use in irrigated cultivation projects around the lagoon’s shores, pollution from pesticide and fertilizer run-off from surrounding agricultural land, increasing levels of tourism, and disturbance from the newly constructed motorway on the eastern bank of the lagoon. The area urgently requires the implementation of a coordinated management plan.