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Do Newly Settled, Field-Collected Oysters and Other Common Sessile Marine Invertebrates Contain Microplastics?

Microplastics 2026
Luciana Banquero, Paul Sacks, Fnu Joshua, Lei Zhai, Joshua S. Sacks, Linda J. Walters

Summary

Scientists checked young oysters and other baby shellfish in a Florida lagoon known for high microplastic pollution to see if these tiny creatures were already loaded with plastic bits. Surprisingly, less than 1% contained microplastics—far fewer than adult oysters from the same area—suggesting these animals may pick up most of their plastic contamination later in life as they grow and filter more water. This matters because it helps clarify when and how the seafood we eat accumulates microplastics, which is an important piece of the puzzle for understanding our own exposure to these pollutants.

Study Type Environmental

Many filter-feeding invertebrates consume microplastics (MP) under laboratory conditions, but little is known about newly settled, field-collected juveniles. To address this information gap, we collected 3439 juvenile invertebrates in the Indian River Lagoon (IRL), FL, USA. Previous studies suggest that the IRL is a MP hotspot. A total of 70% of IRL adult oysters (Crassostrea virginica) contained MP (mean: 2.3 MP/individual), and MP number and MP length were positively correlated with animal size. We predicted that juvenile C. virginica and other sessile invertebrates would contain MP with a positive correlation to animal size. Five species were examined; 51% were C. virginica (mean shell length ± SD: 6.3 ± 4.7 mm). Overall, 117 (3.4%) animals contained potential MP (fibers: 90.7%). Of these particles that matched FTIR databases with a score of 70% or greater, 51% were plastic and 49% were anthropogenically modified particles. No correlations to animal size were found for particle presence (logistic regressions: p ≥ 0.20 for all species) or particle length (linear regressions: p ≥ 0.23 for all species). Thus, even though found in a MP hotspot, our extrapolated results suggest few juveniles (<1%) contained MP. This information is important for understanding the relationship between MP and the life histories of filter-feeding animals, especially for species considered biological indicators of MP.

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