Elucidating the biological reactivity of (aged) micro- and nanoplastic particles in marine invertebrates: From cellular to organismal responses
Hara, J. (2026). Elucidating the biological reactivity of (aged) micro- and nanoplastic particles in marine invertebrates: From cellular to organismal responses. PhD Thesis. University of Antwerp/Ghent University: Antwerp. ISBN 978-94-6357-999-5 . https://dx.doi.org/10.63028/10067/2218560151162165141
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Document type: Dissertation
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| Abstract |
Micro- and nanoplastics (MNPs) are pervasive in marine environments, posing significant ecological risks due to their persistence and physicochemical heterogeneity. Environmental aging alters particle properties, influencing interactions with marine organisms. However, mechanistic understanding of their biological effects under environmentally realistic conditions remains limited. This thesis addresses these gaps by elucidating the biological reactivity of aged MNPs, focusing on cellular, tissue, and organismal responses under environmentally relevant exposure scenarios. A systematic assessment of MNP toxicity in marine invertebrates was conducted using chronic exposure data from the Toxicity of Microplastic Explorer (ToMEx) for Aquatic Organisms database (version v2.0). Species sensitivity distributions were constructed based on fitness-related endpoints, accounting for two distinct toxicity mechanisms. Derived HC₅ values were used to propose provisional thresholds for protecting marine invertebrate communities. Complementary in vivo and in vitro experiments provided integrative evidence that aged polyethylene terephthalate (PET) MPs (~1.9 µm) and NPs (~0.68 µm) elicit cellular- and tissue-level effects in mussels (Mytilus edulis) under environmentally relevant exposure conditions. Results revealed both immediate cellular perturbations and recovery potential. Histopathological analyses demonstrated structural alterations in key organs, particularly the gills, indicating potential impairment of essential physiological functions. Although no mortality or growth effects were observed, exposure induced systemic sublethal responses that may compromise organismal fitness under chronic or combined stress conditions. Through label-free 3D live-cell imaging by holotomography, unlabeled aged PET NPs were successfully resolved within living hemocytes, revealing particle internalization and localization patterns, as well as associated morphological changes. Overall, this thesis advances mechanistic understanding, spanning from community-specific hazard thresholds to the intricate cellular mechanisms underlying particle-induced toxicity. |
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