ASSESSMENT OF THE PHYSICO-CHEMICAL AND BIOLOGICAL QUALITY OF SURFACE WATERS IN ARID AND SEMI-ARID REGIONS OF ALGERIA (NORTH-AFRICA)

Abstract

An assessment of the physico-chemical and the biological quality of surface waters through the use of macroinvertebrates as bioindicators was conducted in two rivers in Algeria, located in semi-arid and arid regions. These are Wadi M’zi (Laghouat region) and Wadi Djedir (Djelfa region). The sampling strategy developed in this work is based on the analysis of the upstream and downstream waters of each watercourse. Eleven physico-chemical parameters (T°C, pH, CE, OD, Cl- , SO4 2-, NO3 - , Salinity, Ca2+, Mg2+ and HCO3 - ) were measured to establish a diagnosis of the state of health of these aquatic ecosystems. Macroinvertebrates were studied using kick-net sampling at eight study sites. The faunistic inventory of benthic macroinvertebrates identified 37 families, mostly represented by insect larvae (96%). Among these, Diptera and Ephemeroptera were the most dominant orders, with other groups being relatively poorly represented. The results obtained show that the physico-chemical quality of the water is slightly deteriorated, but the quality is still evaluated as ‘good’ according to the biotic indices