Diversité taxonomique et structure de la macrofaune benthique des eaux superficielles de l'oued khoumane. Moulay idriss Zerhoun,Maroc (Taxonomic diversity and structure of benthic macrofauna of surface water of Khoumane River. Moulay idriss Zerhoun,Morocco)

Macroinvertebrates of the khoumane river were studied from samples collected monthly from august 2010 to july 2011. the fauna recorded in this work is composed of 17 124 individuals corresponding to 40 families and 60 taxa belonging to three faunistic groups (annelids,molluscs,arthropods). the number of benthic population showed that oligochaeta,diptera,heteroptera,trichoptera and ephemeroptera are dominant. coleoptera,odonata,plecoptera and the crustaceans are only a small fraction of the total fauna. taxa tubifex tubifex,hydropsyche,physa acuta,chironominus sp. and micronecta sp. are numerically more inventoried. the values of the normalized global biological index ranked the upstream water of the river in the category of good quality water and its downstream water into the category of mediocre quality water. analysis of the structure biotypologique by correspondence factor analysis the khoumane river shows that the more we advance downstream,the more we are seeing a decrease or disappearance of taxa polluo-sensitive such as plecoptera and ephemeroptera. the opposite,settled for polluo-tolerant taxa such as chironomidae and oligochaeta. the results obtained in this study show an alarming situation of water quality of the khoumane river and especially in its downstream segment. to address this problem,we recommend the development of the thermal spring ain hamma moulay idriss and purifying of wastewater before to discharge into the river.