Potentially pathogenic bacteria in the plastisphere from water, sediments, and commercial fish in a tropical coastal lagoon: An assessment and management proposal

Microplastics in aquatic ecosystems harbor numerous microorganisms, including pathogenic species. The ingestion of these microplastics by commercial fish poses a threat to the ecosystem and human livelihood. Coastal lagoons are highly vulnerable to microplastic and microbiological pollution, yet limited understanding of the risks complicates management. Here, we present the main bacterial groups, including potentially pathogenic species, identified on microplastics in waters, sediments, and commercial fish from Ciénaga Grande de Santa Marta (CGSM), the largest coastal lagoon in Colombia. DNA metabarcoding allowed identifying 1760 bacterial genera on microplastics, with Aeromonas and Acinetobacter as the most frequent and present in all three matrices. The greatest bacterial richness and diversity were recorded on microplastics from sediments, followed by waters and fish. Biochemical analyses yielded 19 species of potentially pathogenic culturable bacteria on microplastics. Aeromonas caviae was the most frequent and, along with Pantoea sp., was found on microplastics in all three matrices. Enterobacter roggenkampii and Pseudomonas fluorescens were also found on microplastics from waters and fish. We propose management strategies for an Early Warning System against microbiological and microplastic pollution risks in coastal lagoons, illustrated by CGSM. This includes forming inter-institutional alliances for research and monitoring, accompanied by strengthening governance and health infrastructures.