Monitoring and assessment of spatial and seasonal variability in water quality at Lake of Birds (Algeria) using physicochemical parameters and bacterial quality indicators

Water quality assessment is becoming an increasingly important aspect of environmental management. Regular assessment of water quality is essential to ensure the safety of aquatic ecosystems as well as human health. This study aimed at assessing water physicochemical and microbiological proprieties of Lake of Birds (northeastern Algeria). Water samples were monitored monthly (December 2021–November 2022) from three different sites. Quantification of bacterial groups (total heterotrophic bacteria, total coliforms, faecal coliforms, and faecal Streptococci) was coupled with physicochemical characterization of the water (temperature, pH, turbidity, dissolved oxygen (DO), electrical conductivity, total suspended solids, nitrates, nitrites, ammonium, phosphates, biological oxygen demand (BOD5), calcium, magnesium, chloride, potassium, sulfates and hardness). The results of this study were compared with Algerian standards and World Health Organization guidelines. The results show that the water in Lake of Birds has an alkaline pH (9.24), poor oxygenation (DO = 0.55 mg/L), turbidity > 5 NTU, BOD5 > 5 mg/L, potassium > 20 mg/L, and with a very high levels of eutrophic substances (NO₂^–, NH₄⁺ and PO₄^3–). Moreover, the results of the bacteriological analysis indicated the existence of faecal contamination that exceeds the standards, with health risks for humans. Further studies are needed including emerging contaminants and other factors that may impact aquatic ecosystems and to determine how best to maintain their cleanliness and sustainability.