Host-associated microbiota play a critical role in host fitness by providing nutrition, enhancing digestion capabilities, and by providing protection from pathogens. Here, we investigated the effects of two environmental stressors, temperature, and salinity, on the microbiota associated with zebra mussels (ZMs), a highly invasive bivalve in North America. To examine this in detail, lake-collected ZMs were acclimated to laboratory conditions, and subjected to temperature and salinity stress conditions. The impact of these stressors on the diversity, composition, and dynamics of ZM-associated microbiota were assessed by using amplicon- and shotgun-based sequencing, and qPCR-based approaches. Elevated temperature was found to be the primary driver of ZM mortality, although salinity alone also increased its likelihood. Stressor-induced ZM mortality, which ranged between 53 and 100%, was concomitant with significant increases in the relative abundance of several genera of putative opportunistic pathogens including Aeromonas. These genera were only present in low relative abundance in ZMs obtained from the control tank with 0% mortality. Shotgun sequencing and qPCR analyses indicated that the relative and absolute abundances of pathogenic Aeromonas species (particularly A. veronii) were significantly greater in temperature-induced dead ZMs. Taken together, our results show that environmental stress, especially elevated temperature (> 25 °C), is associated with the rapid mortality of ZMs as well as the proliferation of putative opportunistic bacterial pathogens.

宿主相关的微生物群通过提供营养、增强消化能力和提供保护免受病原体的侵害，在宿主健康中发挥着关键作用。在这里，我们研究了两种环境压力因素，温度和盐度，对与斑马贻贝 (ZM) 相关的微生物群的影响，斑马贻贝是北美的一种高侵袭性双壳类动物。为了详细检查这一点，湖中收集的 ZM 适应了实验室条件，并受到温度和盐度压力条件的影响。通过使用基于扩增子和鸟枪法的测序以及基于 qPCR 的方法评估了这些压力因素对 ZM 相关微生物群的多样性、组成和动态的影响。发现升高的温度是 ZM 死亡率的主要驱动因素，尽管单独的盐度也增加了其可能性。压力源引起的 ZM 死亡率，气单胞菌。这些属仅以较低的相对丰度存在于从死亡率为 0% 的对照罐中获得的 ZM 中。Shotgun 测序和 qPCR 分析表明，在温度诱导的死亡 ZM 中，致病气单胞菌物种（特别是A. veronii）的相对和绝对丰度显着更高。总之，我们的结果表明，环境压力，尤其是升高的温度（> 25 °C），与 ZM 的快速死亡以及假定的机会性细菌病原体的增殖有关。