|
Résumé :
|
This article is dedicated to natural reservoirs, widely distributed ecosystems in North Africa but poorly studied. Their hydrological and ecological characteristics are insufficiently highlighted in existing wetland typologies; that’s why we recommend to assign them to new wetlands’ types. Generally named gueltas, these reservoirs have a common genesis model, based on natural dams that block river beds. Four types of gueltas are identified: (1) landslide lakes, mountainous reservoirs created upstream of voluminous landslides that block deep valleys; (2) river gueltas, river beds blocked by small deposit thresholds, generally installed by tributaries; (3) dune gueltas, generated upstream to active Saharan dunes; (4) estuarine gueltas, due to fluviomarine dikes transforming estuaries into large ‘saltwater ponds’. These standing waters are built in river beds, and their characteristics and communities are highly fashioned by floods, both in their composition and functioning. The river gueltas are widely distributed in North Africa, while other reservoirs are poorly represented, some of them being threatened. Permanent reservoirs, in both mountains and desert, host endemic fishes, while river gueltas are conservatories of fish during dry seasons. Considering these originalities and values, several Moroccan gueltas have been classified in Ramsar sites, hoping they would benefit from future studies.
|