Coastal ecosystems face increasing threats from anthropogenic pollution and environmental stressors like hypoxia and nanoparticle exposure. The Baltic Sea exemplifies these challenges due to nutrient pollution and hypoxia. We investigated the combined effects of zinc oxide nanoparticles (nZnO), which possess unique properties such as high reactivity and bioavailability, and hypoxia on bioenergetics and metabolite homeostasis of the blue mussel Mytilus edulis from the Baltic Sea. Mussels were first exposed to environmentally relevant concentrations of nZnO (100 μg Zn L⁻¹) and subsequently subjected to short-term (24 h) or long-term (7 d) hypoxia (<0.1% air saturation) followed by recovery periods (1 h and 24 h). Our findings reveal complex effects of nZnO on mussel metabolism under normoxic and hypoxic conditions. Under normoxic conditions, nZnO alters mussel metabolism without causing energy deficit. Prolonged severe hypoxia induces anaerobic metabolism and glycogen depletion. Under hypoxic conditions, nZnO disrupts mussels' metabolic response to anaerobic conditions, threatening their anaerobic survival capacity. Control mussels swiftly recover metabolic homeostasis upon reoxygenation, whereas nZnO-exposed mussels show delayed recovery, with ongoing energy disturbances. Overall, these findings underscore the metabolic impacts of nZnO and hypoxia in keystone marine mussels and emphasize the importance of considering oxygen levels in assessments of nanoparticle toxicity in coastal ecosystems.

中文翻译：

---

纳米污染物 （nZnO） 和缺氧对海洋双壳类 Mytilus edulis 生物能量学和代谢稳态的协同影响


沿海生态系统面临着来自人为污染和环境压力源（如缺氧和纳米颗粒暴露）的日益严重的威胁。波罗的海是营养物污染和缺氧带来的这些挑战的例证。我们研究了具有高反应性和生物利用度等独特特性的氧化锌纳米颗粒 （nZnO） 和缺氧对波罗的海蓝贻贝 Mytilus edulis 的生物能量学和代谢物稳态的综合影响。贻贝首先暴露于环境相关浓度的 nZnO （100 μg Zn ^L-1） 中，随后进行短期 （24 h） 或长期 （7 d） 缺氧 （<0.1% 空气饱和度），然后是恢复期 （1 h 和 24 h）。我们的研究结果揭示了 nZnO 在常氧和低氧条件下对贻贝代谢的复杂影响。在常氧条件下，nZnO 会改变贻贝的代谢而不会造成能量损失。长期严重缺氧会诱导厌氧代谢和糖原耗竭。在缺氧条件下，nZnO 会破坏贻贝对厌氧条件的代谢反应，威胁其厌氧生存能力。对照贻贝在再氧合后迅速恢复代谢稳态，而暴露于 nZnO 的贻贝恢复延迟，并伴有持续的能量紊乱。总体而言，这些发现强调了 nZnO 和缺氧对关键海洋贻贝的代谢影响，并强调了在评估沿海生态系统纳米颗粒毒性时考虑氧水平的重要性。