Diversity and characteristics of microplastics in bivalves from Tam Giang Lagoon

This study examines the diversity and characteristics of microplastic (MP) contamination in bivalve mollusks collected from the Tam Giang Lagoon, Vietnam-one of Southeast Asia's largest lagoon systems. A total of 52 specimens representing three species-mussels (Sinanodonta woodiana), green mussels (Perna viridis), and clams (Corbicula subsulcata)-were analyzed, yielding 457 MP particles. Clams contributed the highest proportion (50.55%), followed by green mussels (33.48%) and mussels (15.97%). The average MP density was 3.17 MP particles/g in green mussels, 3.04 MP particles/g in clams, and 0.42 MP particles/g in mussels. Conversely, when normalized per individual, mussels exhibited the highest accumulation (12.17 MP particles/individual), followed by green mussels (10.20 MP particles/individual) and clams (7.45 MP particles/individual), showing a positive correlation between MP density and organism size. Fibers dominated all samples (64.07-84.31%), while fragments were less frequent and pellets were absent. Most MPs were smaller than 0.5 mm, and black was the predominant color in all species. These findings highlight distinct species-specific accumulation patterns likely driven by habitat characteristics, filtration capacity, and feeding behavior. Overall, this research provides essential baseline data on microplastic pollution in the Tam Giang Lagoon and underscores the ecological significance of bivalves as bioindicators of sediment-associated MP contamination in coastal ecosystems.