By 2040, tire particles (TP) are expected to dominate marine plastic contamination, raising concerns about their effects on marine animals. This study employed a multidisciplinary and multigenerational approach on the Pacific oyster Magallana gigas to investigate the effects of TP and their leachates (LEA). Effects were analysed at the individual scale, from cellular, molecular, and microbiota changes to reproductive outputs and offspring performance. Microbiota characterization revealed potential dysbiosis in oysters treated with high concentration of both TP and LEA. RNA-seq analyses highlighted the activation of energy metabolism and stress responses in the LEA treatment. Additionally, transcriptional changes in oocytes and the reduction of motile spermatozoa suggested potential effects on gamete quality. Notably, possible oyster resilience was pointed out by the lack of significant ecophysiological modifications in adults and impacts on the growth and reproductive outputs of the offspring. Overall, the implications of the observed oyster resilience under our experimental setting are discussed in relation to available toxicity data and within a comprehensive view of coastal ecosystems, where a higher diversity of plastic/rubber materials and harsher environmental conditions occur.

Environmental Implications

Tire particles and associated chemicals led to the disruption of oysters’ energy metabolism and the activation of molecular mechanisms involved in stress response. Possible impacts on gamete quality and the spread of opportunistic pathogens have also been observed. Fortunately, the lack of significant long-term consequences regarding fertilization success, growth and reproductive outputs of the offspring suggests possible oyster resilience. However, the increase of tire particles concentrations and the harsher environmental conditions compared to our laboratory experimental setting expected in the coming years are of particular concern for the conservation of species chronically exposed to tire particles and associated chemicals.