Flora in North Africa is known by its richness (approximately 8,000 species), taxonomic diversity and high number of endemic species. Due to its geographical location, North Africa contains in fact floristic elements of both Euro-Siberian and tropical regions. Although poor in water resources, the region shows in fact a good representation of aquatic and wetlands habitat, very diverse in water quality, biological and hydrological aspects; this is why a relatively high diversity degree can be found here. A total of 645 species and sub-species of aquatic plants have been reviewed in the region. Among these, 521 aquatic plants belonging to 67 families have been assessed: of these 72% are perennial and 28% annual, with the most highly represented families being Cyperaceae (84 species), Poaceae (59 species) and Asteraceae (33). Out of these 521 species, only 509 have been classified according to the IUCN Red List of Threatened Species (being 12 species non-indigenous and classified as Not Applicable for these purposes).
North Africa Freshwater Aquatic Plants
Freshwater habitats and biodiversity are recognized to be under serious threat at global level. Although poor in water resources, the North Africa region shows a good representation of aquatic and wetlands habitat and species richness is particularly high in the mountains and littoral areas on the Mediterranean side where wetland habitats concentrate. Monitoring freshwater basins is therefore important to prevent the loss of these ecosystems and freshwater aquatic plants have been identified as one of the priority taxa indicators for the overall conservation status of wetland ecosystems.
Of the 509 species assessed, one is today Regionally Extinct; Laurembergia tetrandra, previously found in Algeria and now extinct due to water abstraction from the Black Lake (1990-1991). At regional level, a total of 122 species (24%) are threatened: 68 species (13.4%) are Vulnerable, 27 (5.3%) are Endangered and 27 (5.3%) Critically Endangered. Over half are not threatened, with 52.3% classified as Least Concern and 13.4% as Near Threatened. Finally, 52 species (10%) have been assigned to the Data Deficient category as insufficient information was available to properly assess them. Among the 75 species of aquatic plants endemic to the region, 33 (44%) have been assessed as threatened, with 16 classified as Vulnerable (21%), 7 as Endangered (9%), and 10 as Critically Endangered (13%). Among these endemics, 9 are today Data Deficient. Morocco is the country where most threatened endemic species occur (21 species; 29.3%).
The highest number of species is found in Morocco (388 species) and Algeria (331 species), with lower numbers in Tunisia (239), Egypt (226) and Libyan Arab Jamahiriya (133). Species richness is particularly high in the mountains and littoral areas on the Mediterranean side (northern of the Maghreb and Lower Nile Valley) where wetland habitats concentrate, strongly decreasing towards the southern and more arid regions.
Endemic species follow the same pattern as above and are found mainly in the Mediterranean part of the Maghreb, mostly confined to the high mountains of Morocco and Algeria. They have also been found, to a lesser extent, in the littoral plains characterized by higher rainfall and in the Nile Delta.
Most threatened aquatic species are found in the Mediterranean and Atlantic coastal zones, with higher levels of richness in temporary ponds, marshes, streams and lakes in Morocco and the east of the Maghreb. In these areas, main threats are directly linked to land use and water exploitation.
Aquatic plants in North Africa are threatened mainly by habitat loss and degradation (95% of the species) primarily due to underground water extraction, the intensification of agriculture and infrastructure development. Agricultural activities use over 80% of the total water resources available for wetlands and fluvial ecosystems, also polluting waters and soils and affecting 52% of threatened species. As a result, approximately 28% of the wetlands in Tunisia have disappeared during the last 100 years. Drought is affecting 12 of the species assessed and, though some species show some resilience, the impact of more acute droughts due to climate change is not known yet. Leisure activities (such as picking plants) and tourism equally have an impact, affecting 39% of the threatened species. Invasive exotic plants are also a threat to many aquatic plants, especially in Egypt, where many invasive species from African tropical countries enter via the Nile. Moreover, intrinsic factors such as endemism, range limitation, low dispersal rate, and large population fluctuation can increase the risk of extinction, actually posing a threat to 48% of the species assessed as threatened in North Africa.
Regional biodiversity hotspots for aquatic plants
Based on total aquatic plants richness (>104) and endemic species richness (>10), three aquatic biodiversity hotspots have been identified in North Africa:
- the Betico-Rifan arc, stretching across northern Morocco and western Algeria;
- the Middle and High Atlas mountains;
- the Kablylias-Noumidia-Kroumiria complex, stretching from Algeria to Tunisia.
Another small area of endemic species richness is in the Atlantic plains of Morocco. Here the richness may be due to the abundance and diversity of wetlands, as well as to populations spreading from the two neighboring hotspots.
Conclusions and recommendations for conservation
- An integrated management of habitats and natural resources should be achieved by each country in order to reduce habitat loss and strengthen existing protection measures.
- Information is lacking for 10% of the aquatic flora, which highlights the need for more field investigations, in particular in Egypt and Libyan Arab Jamahiriya, where there are no studies for any of the nine endemics recorded.
- Wetland conservation is crucial to the long-term conservation of aquatic plants in North Africa and all wetlands, not only hotspots, need better conservation. However, a deeper comprehension of the links between ecosystem functions and species demography is necessary for a sustainable management of habitats and species.