Nowadays, pesticides and microplastics (MPs) are commonly found in coastal waters worldwide. Due to their widespread use, their persistence and toxicity, they may induce adverse effects on physiology and behaviour of marine organisms such as the Pacific oyster (Crassostrea gigas). This study explored the growth and valve activity of juvenile oysters exposed for 24 days to two frequently detected pollutants in the Pertuis Charentais (South West, France): a herbicide (chlortoluron, 85 µg.L⁻¹) and high-density polyethylene microparticles (HDPE 20-25 µm, 112 MP.mL⁻¹) alone or in combination (cocktail condition; 97 µg.L⁻¹ of chlortoluron + 108 MP. mL⁻¹). The valve activity of juvenile oysters recorded by using a High Frequency and Non-Invasive valvometer (HFNI) was characterized by three parameters: the number of valve micro-closures (VMC), the Valve Opening Amplitude (VOA), and the Valve Opening Duration (VOD). Additionally, daily shell growth and the oyster daily rhythm were assessed. The exposure to MPs of oysters led to a significant increase of VMC and a decrease of VOD and shell growth. The exposure to chlortoluron showed a significant increase of VOA and a decrease of VMC. In combination with MPs, chlortoluron still increased VOA and decreased VMC but also reduced the shell growth. Chronobiological analysis did not reveal any effects on the daily rhythm of both contaminants. This work highlighted significant effects of high environmental concentrations of MPs and Chlortoluron on the behaviour and growth of the Pacific oyster.

如今，杀虫剂和微塑料 (MPs) 普遍存在于全球沿海水域。由于它们的广泛使用、它们的持久性和毒性，它们可能对太平洋牡蛎（Crassostrea gigas）等海洋生物的生理和行为产生不利影响。本研究探讨了在 Pertuis Charentais（法国西南部）中暴露于两种经常检测到的污染物 24 天的幼牡蛎的生长和瓣膜活动：除草剂（氯酮，85 µg.L ^-1）和高密度聚乙烯微粒（ HDPE 20-25 µm, 112 MP.mL ^-1 ) 单独或组合使用（鸡尾酒条件；97 µg.L ^-1氯酮 + 108 MP.mL ^-1）。使用高频无创阀瓣计 (HFNI) 记录的幼牡蛎的瓣膜活动由三个参数表征：瓣膜微闭次数 (VMC)、瓣膜开启幅度 (VOA) 和瓣膜开启持续时间（点播）。此外，还评估了每日贝壳生长和牡蛎的每日节律。牡蛎暴露于 MPs 导致 VMC 显着增加，VOD 和壳生长减少。暴露于氯吡脲显示 VOA 显着增加和 VMC 降低。与 MP 结合使用时，氯脲酮仍会增加 VOA 并降低 VMC，但也减少了壳的生长。时间生物学分析未显示对两种污染物的日常节律有任何影响。