Ecotoxicological Effects of Polystyrene Micro- and Nanoplastics in Aquatic Ecosystems Under the Influence of Temperature

Understanding the toxicity of micro- and nanoplastics (MNPs) in aquatic systems, combined with temperature, is essential in order to assess ecological hazard in a multi-stressor environment. This study investigated the biological responses of marine and freshwater organisms of different trophic levels (including primary producers, decomposers, and consumers) exposed to polystyrene (PS) MNPs, tested at varying concentrations and particle sizes under two temperature conditions (control and +2 °C). Overall, differences were observed between trophic levels: Paracentrotus lividus larvae were more sensitive to higher temperatures, Daphnia magna exhibited a non-linear pattern, and microalgae have generally shown low sensitivity to both MNPs and high temperatures. However, the MNPs’ responses were not generally concentration-dependent, with the exception of Dunaliella tertiolecta. The effects recorded at increased temperature generally varied among species, indicating that even a moderate increase in temperature can modulate responses in different organisms. In the marine system, hazard levels increased with temperature, whereas in freshwater, they were higher but temperature-independent. These results highlight the importance of integrated assessment approaches to accurately evaluate the ecological hazard associated with MNPs pollution in the context of climate change.