Assessment of the coastal and estuarine environment quality of western Algeria using the bioindicator Polychaeta; the genus Nereis

This study was carried out in the Cheliff estuary and adjacent coastal areas to determine in particular the impact of environmental stress on the biodiversity of the Western-Algerian littoral Polychaeta, with the motive to analyze the health status of the marine ecosystem as bio-indicator species of pollution. Monitoring took place in five stations (Sokhra, Hadjaj, Salamandre, and Sonactere) during the wet and dry seasons in 2014 respectively, including Cheliff estuary as a reference site and the other four coastal sites. We detected in total, four taxa comprising 392 individuals. The taxa having the highest frequency rate were Nereis virens (62%), Nereis diversicolor (58%), Nereis falsa (43%), and Nereis pelagica (51%). We noted low Polychaeta abundances in Sokhra and Hadjaj stations, in the Eastern area of Cheliff Estuary with a high pH, OS, DO, and Chlorophyll “a”. Cheliff Estuary has high nutrients, N. diversicolor, and N. virens values. The sites Salamandre and Sonactere in the Western part of the Cheliff Estuary have high BOD, COD, PO4, suspended solids, turbidity, N. pelagica, and N. falsa. The data monitoring and analysis of the stations based on similarities of Annelida communities show the link between the components of the environment and the biodiversity abundance.