Freshwater quality is a major ecological factor in maintaining trophic levels and the survival of aquatic ecosystems. This preliminary study was carried out in 2008 and 2009 at the level of four wetland stations in Niamey, Niger. We characterized the physicochemical properties of the waters of lentic and lotic environments as well as the diversity of their populations of algae of the genus Micrasterias. Our analyses indicated that mineral and nutrient levels were higher in sites near the Niger River bank and in adjacent floodplains than in the middle of the river. This could be explained by the discharge of wastewater as well as by the use of organic fertilizers by coastal crops. Likewise, the richest community of Micrasterias species has also been identified along the river and in flood zones.
Our results therefore suggest that the water used for irrigation is of good quality. A total of 27 species of Micrasterias were recorded in the waters of the sites analyzed. However, these species were more numerous in
the Niamey 2 sites than in those of Niamey 1 which are along the river and in flood zones. The abundance of Micrasterias sp. suggests that the waters at the sites studied are of good quality. Physicochemical analyses also confirmed the good quality of the waters surveyed.