Beyond the tip of the iceberg: widespread plastic and cellulosic contamination in fish consumed by island populations of French Polynesia

Marine organisms across Pacific Islands are increasingly exposed to a complex mixture of anthropogenic particles, yet regional patterns of contamination and the relative contribution of plastic particles versus cellulosic fibers remain poorly understood. Here, by examining 180 fish from two reef species across six islands and 12 tuna specimens from the open ocean, we provide the first multi-species, multi-island assessment of debris (> 100 µm) ingested by fish in French Polynesia. Visual inspection and Nile Red screening of all samples were combined with µ-FTIR confirmation on a subset of particles to determine their composition, while maintaining broad analytical coverage. Our results show widespread contamination, with plastic particles detected in 85 fish (44%) whereas cellulosic microfibers of anthropogenic origin were present in 128 fish (67%), highlighting microfibers as a prominent contaminant. Contamination levels per fish averaged 0.7 ± 0.1 plastic particle and 2.0 ± 0.2 colored fibers. Abundant plastics were polyamide and polypropylene, followed by acrylonitrile, polyethylene and polyvinylstearate in smaller proportions. Although contamination profiles displayed intra- and inter-specific variabilities, we hypothesized that they were likely influenced by both human presence and hydrodynamic processes. Our findings underline the need for further research on the ecological and toxicological implication of anthropogenic fibers in remote tropical ecosystems like French Polynesia.