Co-exposure of mercury and microplastics in aquatic food webs: A review of sources, bioaccumulation, and ecotoxicological risks.

The intensification of anthropogenic activities has led to the widespread release of micropollutants, including mercury (Hg), into aquatic environments. Mercury is a persistent and hazardous contaminant with severe ecological and human health implications. Previous reviews have primarily examined mercury or microplastics (MPs) in isolation, but the novelty of this study lies in its focus on their co-exposure and combined impacts within aquatic food webs. Specifically, this review addresses the central research question: how do mercury and microplastics jointly influence bioaccumulation and ecotoxicological risks? To answer this, 92 peer-reviewed articles published since 2010 were systematically analyzed, with 58 % focusing on marine environments. A bibliometric analysis revealed a growing research emphasis on mercury-MP interactions, highlighting their emerging importance. Case data indicated extremely high mercury concentrations in the Agadir coastline, Morocco (up to 440 μg/L), while among fish species, Thunnus obesus (Bigeye tuna) and Rhaphiodon vulpinus exhibited the highest reported burdens (>6000 ng/g dry weight). Moreover, several studies documented a strong positive correlation (R2 = 0.68) between mercury levels in water and fish tissues. Collectively, these findings demonstrate the ecological risks posed by combined contaminant pathways and underscore the urgent need for comprehensive monitoring, regulatory measures, and policies to protect aquatic ecosystems and public health.