Phytoplankton are characterized by a great phenotypic plasticity and amazing morphological variability, both playing a primary role in the acclimation to changing environments. However, there is a knowledge gap concerning the role of algal morphological plasticity in stress responses and acclimation to micropollutants. The present study aims at examining palmelloid colony formation of the green alga Chlamydomonas reinhardtii upon micropollutants exposure. Cells were exposed to four micropollutants (MPs, copper, cadmium, PFOS and paraquat) with different modes of action for a duration of 72 h. Effects of MPs on palmelloid formation, growth and physiological traits (chlorophyll fluorescence, membrane integrity and oxidative stress) were monitored by flow cytometry and fluorescence microscopy. Palmelloid formation was observed upon treatment with the four micropollutants. Number of palmelloid colonies and their size were dependent on MP concentration and exposure duration. Cells reverted to their unicellular lifestyle when colonies were harvested and inoculated in fresh medium indicating that palmelloid formation is a plastic response to micropollutants. No physiological effects of these compounds were observed in cells forming palmelloids. Palmelloid colonies accumulated lower Cd concentration than unicellular C. reinhardtii suggesting that colony formation protects the cells from MPs stress. The results show that colony formation in Chlamydomonas reinhardtii is a stress response strategy activated to face sub-lethal micropollutant concentrations.

浮游植物的特点是具有出色的表型可塑性和惊人的形态变异性，两者在适应不断变化的环境中均起着主要作用。但是，关于藻类形态可塑性在应激反应和适应微污染物中的作用方面存在知识差距。本研究旨在检查绿藻衣藻衣藻的棕榈状菌落的形成。暴露于微量污染物时。将细胞暴露于四种具有不同作用方式的微污染物（MP，铜，镉，PFOS和百草枯）72小时。通过流式细胞术和荧光显微镜监测MPs对棕榈果形成，生长和生理特性（叶绿素荧光，膜完整性和氧化应激）的影响。在用四种微量污染物处理后观察到棕榈果形成。棕榈状菌落的数量及其大小取决于MP浓度和暴露时间。当收集菌落并将其接种在新鲜培养基中时，细胞恢复了其单细胞生活方式，这表明棕榈果胶的形成是对微污染物的塑性反应。在形成棕榈果胶的细胞中未观察到这些化合物的生理作用。C. reinhardtii暗示集落形成可保护细胞免受MPs压力。结果表明，莱茵衣藻中的菌落形成是一种激活的应激反应策略，可应对亚致死性的微污染物浓度。