Assessment of microplastic pollution: distribution, composition, and sources in the El-Mellah (Algeria) and Bizerte (Tunisia) Mediterranean lagoons

Microplastic (MP) pollution poses a growing threat to coastal ecosystems worldwide. This study evaluates the abundance, spatial distribution, shapes, and polymer composition of MPs in two Mediterranean lagoons: El-Mellah (Algeria) and Bizerte (Tunisia). Quantitative analysis revealed high MP concentrations in both lagoons, with mean values of ∼75.7 particles kg-1 in El-Mellah and ∼73.4 particles kg-1 in Bizerte. El-Mellah exhibited a more homogeneous spatial distribution, whereas Bizerte showed marked site-to-site variability. Fragments were the dominant shape category in both systems (up to 55% in Bizerte and 51% in El-Mellah), while fibers were relatively more abundant in El-Mellah (up to 38%). Polyethylene was the most prevalent polymer (33-44%), followed by polyethylene terephthalate (22-31%) and polypropylene (17-22%), reflecting common plastic usage patterns and discharge sources. These findings highlight distinct pollution dynamics linked to local anthropogenic activities and hydrodynamic conditions. The study underscores the urgent need for targeted management and monitoring strategies to mitigate MP contamination and protect these ecologically important lagoon environments.