Thesis defence by Andry Rabezanahary

Title: Environmental microplastics toxicity in focus: riverine spatio-temporal distribution and hazard assessment in freshwater fish based on in situ and in vivo approaches

Summary:

The widespread production and use of plastics have led to their continuous release into the environment. Microplastics (MPs) are now ubiquitous in aquatic ecosystems, where their bioavailability to organisms and potential entry into the food web raise serious environmental and public health concerns. Substantial progress has been made in understanding MP toxicity, and their hazardous potential is now widely acknowledged. However, MP toxicity studies remain complex, as multiple particle characteristics, such as size, shape, polymer type, and sorbed contaminants might influence both bioavailability

To bridge this gap, the present thesis adopted a dual, complementary approach: (i) characterizing the environmental occurrence and bioavailability of MPs, and (ii) assessing the ecological relevance of using environmentally derived MPs in in vivo toxicity experiments.

Overall, this thesis provides insights into the reproductive and transgenerational effects of environmentally relevant MPs while underscoring the importance of considering particle–pollutant interactions. By combining in situ field data with in vivo laboratory experiments, it demonstrates that the use of environmentally derived MPs represents a more realistic and ecologically meaningful approach to hazard characterization. Further studies should be carried out in this same perspective to generate robust, exploitable data and contribute to establishing a comprehensive MP risk characterization.

Andry will present the results of his PhD thesis, conducted in the Biology Department (URBE), under the supervision of Patrick Kestemont, with Omayma Missawi & Valerie Cornet.