Effect of the Nature of the Substrate and the Environmental Parameters on the Biodiversity of the Benthic Macrofauna of the Upper Cheliff Hydrographic Network (W. Medea and Ain Defla. Algeria)

The sampling carried out at the level of the upper Chéliff hydrographic network made it possible to collect 11,035 individuals. The taxonomic group of insects dominates the population with 94.35% followed by molluscs with 5.61% and crustaceans with 0.04%. The group of insects is the most diverse and abundant. It is represented by 6 orders of which the order Diptera is the most represented with 64.6% (6726 individuals), followed by Ephemeroptera with 24.1% (2509 individuals), Heteroptera with 5.11% (532 individuals), Coleoptera with 3.59% (374 individuals), Trichoptera with 1.9% (198 individuals) and Odonata with 0.66% (73 individuals) of the total number of insects. We note a total absence of Plecoptera at all study stations. The results of canonical correspondence analysis (CCA) show 3 groups: group 1 formed by stations which are characterized by a much muddier substrate. Groups 2 and 3 are formed by stations which are characterized by a heterogeneous substrate but with a different degree of pollution. The results show that the stations which are characterized by a muddy substrate harbor less diversified and less rich benthic macrofauna compared to the other stations which have a heterogeneous substrate. And the polluted stations harbor less diversified and less rich benthic macrofauna compared to the other stations.