POLLUTION MONITORING FOR AQUATIC ECOSYSTEM INTEGRITY USING BIOTIC INDICES BASED ON MACROINVERTEBRATES: CASE STUDY, TONGA LAKE, NORTH-EAST ALGERIA

The aim of this study was to estimate the diversity of aquatic macroinvertebrates and evaluate the water quality of Tonga Lake (Algeria). Tonga is about 2,700 ha with an average depth of 1.20 m. It is communicating with the Mediterranean Sea through an artificial channel called Messida. The collection of aquatic macroinvertebrates from the seven stations was carried out in the coastal area from March 2017 to February 2018. For this purpose, we used both physicochemical variables and three biotic indices: 1) the FBI (Family Biotic Index); 2) the BMWP (Biological Monitoring Working Party); and 3) the ASPT (Average Score Per Taxon). The indices were calculated using fauna collected from seven stations along the littoral of Tonga Lake. The fauna recorded in this work is composed of seven orders; the most dominant orders were Heteroptera (24.87%), Diptera (21.41%), followed by Coleoptera (19.39%), Ephemeroptera (17.20%), Basommatophora (13.56%), Odonata (3.46%), and Acari (0.12%). The results also revealed that the BMWP index value classified Tonga Lake as having medium biological quality, while the FBI and ASPT indices classified it as having poor biological water quality.