Historical Baseline Assessment of Coastal Pollution in Bou Ismaïl Bay (Algeria) Using a Multi- Compartment Biomonitoring Approach
Year: 2026
Type: preprint
Abstract: Coastal anthropization poses a severe threat to Mediterranean littoral ecosystems. This study provides a historical baseline for assessing long-term environmental changes in Bou Ismaïl Bay (central Algerian coast) across three sectors exhibiting varying anthropogenic pressures: Tipaza (Corne d’Or, reference), Bou Ismaïl (highly industrialized), and Sidi Fredj (urban/touristic), where comprehensive multi-compartment datasets remain scarce. Surface seawater, Posidonia oceanica sheaths/rhizomes, superficial matte sediments, and the sea urchin Paracentrotus lividus were concurrently sampled to assess physicochemical parameters, dissolved nutrients, fecal indicator bacteria, and trace element (Al, Cu, Fe, Hg, Mn, Zn) bioaccumulation. The results revealed marked spatial gradients associated with varying levels of anthropogenic pressure. Bou Ismaïl Bay exhibited elevated nutrient concentrations consistent with eutrophic conditions and fecal contamination, driven by massive ammonium (10.30±8.70 μ"M" ) and reactive phosphate (2.40±5.10 μ"M" ) enrichment alongside high mean total coliform counts (5,000±6,925" CFUs/100 mL" ), violating international bathing security margins. This multi-source pollution caused a substantial decline of P. oceanica meadows; shoot densities dropped into the "unsatisfactory" quality status in Bou Ismaïl and Sidi Fredj compared to the reference site. Concurrently, the meadow Conservation Index crashed from 0.80 to 0.40, signaling a pronounced ecological shift toward dead matte. Ecotoxicological analyses identified the organic-rich sedimentary matte as a major long-term geochemical sink, with iron (73,03±39,900" mg/kg" dw) and zinc (500±8.0" mg/kg" dw) skyrocketing in the heavily impacted bay. Furthermore, a sharp localized mercury anomaly was detected in P. oceanica rhizomes at Sidi Fredj (0.700±0.015" mg/kg" ), may reflect localized contamination associated with historical marina activities. Overall, these findings indicate a marked degradation of key biological indicators under increasing anthropogenic pressure and highlight the urgent need for local wastewater purification systems to safeguard southern Mediterranean coastal ecosystems.
Source: Research Square
Authors: Rachida GHALMI, Fateh TARMOUL, Juba CHABANE
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204904394