Hormesis-like growth and photosynthetic physiology of marine diatom Phaeodactylum tricornutum Bohlin exposed to polystyrene microplastics

The effects of pristine polystyrene microplastics (pMPs) without any pretreatment at different concentrations (0, 10, 20, 50, and 100 mg/L) on Phaeodactylum tricornutum Bohlin two initial algae densities (105 106 cells mL) were assessed in this study. Hormesis-like found when microalgae grew with pMPs. results showed that pMPs inhibited growth under a high concentration tolerated by individual algal cell (low density) (up to −80.18±9.71%) but promoted the situation was opposite 15.27±3.66%). contents photosynthetic pigments including chlorophyll a, c carotenoids resistance stress low density increased time, true density. Compared group, Qp received less inhibition, NPQ (heat dissipation) also decreased Under density, OJIP parameters such as Sm, N, Area, Pi Abs, Ψo, φEo, TRo/RC ETo/RC more perturbed initially returned levels control group (without pMPs) over they remained stable throughout experiment These show marine environment may have toxic P. stages, which is great significance for understanding impact aquatic ecosystems.