EVALUATION OF THE PHYSICO-CHEMICAL AND BIOLOGICAL QUALITY OF THE EASTERN ALGERIAN COASTAL WATERS (SOUTHWESTERN MEDITERRANEAN)

This study aimed to investigate the water quality of the eastern Algerian coastal area as well as the responses of the major phytoplankton groups to the variability of the physico-chemical parameters. The analysed parameters (dissolved oxygen, pH, sea surface temperature, and salinity) are found to be within the tolerated ranges. Whereas the nutrients surpassed the standards, especially on the western and central sides of Annaba Gulf, where anthropic pressures are constantly increasing. Those concentrations were less important on El Kala’s coast, which is considered a reference zone, with the exception of certain elevated levels of silicate, nitrate, and ammonium detected in August, but which do not exceed the tolerated standards. Nevertheless, adjacent to El Mellah Lagoon, double the phosphate permissible level was recorded. When it comes to the phytoplankton, the highest densities were detected on the onshore of Annaba, associated with the strong concentrations of nutrients coming from the terrigenous supply of Seybouse and Boudjemma wadis, as well as from Mafragh Estuary. Referring to previous studies conducted at the level of Annaba Gulf, we noticed that the enrichment of the coast in nutrients of various origins is intensifying, which disrupts the aquatic balance, starting with its basis, which is the phytoplankton.