Algal bloom-mediated microplastic dispersion in coastal areas of West Africa: Integrated insights and risk projections from molecular models and remote-sensed evaluations

Algal blooms along the West African coast threaten ecosystems and human health due to nutrient enrichment and rising temperatures. This remote-sensing study examined the relationships between chlorophyll-a concentrations, environmental variables, and the potential for microplastic retention in blooms using molecular docking models for predictive insights. Correlation analyses revealed region-specific associations, with moderate positive correlations between chlorophyll and temperature along the southwest Nigeria-Togo coastline and near Liberia and Sierra Leone (r = 0.2-0.4) and strong correlations with particulate carbon across most regions (r = 0.6-0.8). Chlorophyll fluorescence correlations were generally low (r = 0.2), except for higher correlations in the Senegal-Gabon and Côte d'Ivoire-Ghana stretches, indicating that localized factors influence bloom dynamics. Molecular docking results predict that polycarbonate microplastics have the strongest binding affinities with algal proteins, particularly flagellin (-11.3 kcal/mol), suggesting significant retention potential within bloom matrices. In contrast, ethylene plastics displayed weaker interactions (up to -2.2 kcal/mol) and a high dissociation constant (Kd = 0.079 M), indicating minimal retention potential. The low Kd values for polycarbonateprotein interactions (e.g., 5.15e09 M for flagellin) predict a concerning scenario where microplastics become increasingly integrated into algal biomass, increasing exposure risks for marine life. Warm, nutrient-rich conditions along the West African coast, especially from southwest Nigeria to Togo and Côte d'Ivoire to Sierra Leone, are expected to increase the frequency and severity of algal blooms. This proliferation disrupts biodiversity and water quality while straining local fisheries by altering marine food webs. To mitigate microplastic entrapment from algal blooms and protect vulnerable marine ecosystems, targeted monitoring and intervention strategies are essential.