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Microplastics absent from reef fish in the Marshall Islands: Multistage screening methods reduced false positives



Katherine Shaw, Jonathan Whitney, Eileen Nalley, Madeline Schmidbauer, Megan Donahue, Jesse Black, Raquel Corniuk, Kellie Teague, Catherine Pirkle, Rachel Dacks, Max Sudnovsky, Jennifer Lynch


Island communities, like the Republic of the Marshall Islands (RMI), depend on marine resources for food and economics, so plastic ingestion by those resources is a concern. The gastrointestinal tracts of nine species of reef fish across five trophic groups (97 fish) were examined for plastics >1 mm. Over 2100 putative plastic particles from 72 fish were identified under light microscopy. Only 115 of these from 47 fish passed a plastic screening method using Fourier-transform infrared microspectroscopy (μFTIR) in reflectance mode. All of these were identified as natural materials in a final confirmatory analysis, attenuated total reflectance FTIR. The high false-positive rate of visual and μFTIR methods highlight the importance of using multiple polymer identification methods. Limited studies on ingested plastic in reef fish present challenging comparisons because of different methods used. No plastic >1 mm were found in the RMI reef fish, reassuring human consumers.
Marine Pollution Bulletin


microplastic, FTIR, Marshall Islands, reef fish, ingestion


Shaw, K. , Whitney, J. , Nalley, E. , Schmidbauer, M. , Donahue, M. , Black, J. , Corniuk, R. , Teague, K. , Pirkle, C. , Dacks, R. , Sudnovsky, M. and Lynch, J. (2023), Microplastics absent from reef fish in the Marshall Islands: Multistage screening methods reduced false positives, Marine Pollution Bulletin, [online],, (Accessed July 15, 2024)


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Created November 29, 2023, Updated November 30, 2023