Intérêt des Characeae comme bioindicateurs de la qualité des eaux : le cas des zones humides de Numidie (Nord-Est algérien)

Characeae surveys and water physico-chemical studies have been performed during four years (2007-2011) on 41 wetlands of Numidia (NE Algeria). Among the 12 species inventoried in the region, four are rare in North Africa and one, Nitella batrachosperma, is new for Algeria. Comparison between Characeae communities and phosphate contents shows that (1) Characeae have nearly disappeared from habitats that contain high levels of orthophosphates (> 780 μg.l-1), (2) three species of Chara (C. globularis, C. gymnophylla and C. vulgaris) characterize medium-polluted habitats (213-780 μg.l-1), where they are often present as discontinuous populations, and (3) the Nitella (N. opaca and N. translucens) are good indicators of low water pollution (< 70 μg.l-1). In addition to the sole presence of a given species, the physiological appearance of the plants has to be taken into consideration as a sign of a healthy population.