The prolonged ice cover inherent to alpine lakes incurs unique challenges for aquatic life, which are compounded by recent shifts in the timing and duration of ice cover. To understand the responses of alpine zooplankton, we analyzed a decade (2009–2019) of open-water samples of Daphnia pulicaria and Hesperodiaptomus shoshone for growth, reproduction and ultraviolet radiation tolerance. Due to reproductive differences between taxa, we expected clonal cladocerans to exhibit a more rapid response to ice-cover changes relative to copepods dependent on sexual reproduction. For D. pulicaria, biomass and melanization were lowest after ice clearance and increased through summer, whereas fecundity was highest shortly after ice-off. For H. shoshone, biomass and fecundity peaked later but were generally less variable through time. Among years, ice clearance date varied by 49 days; years with earlier ice-out and a longer growing season supported higher D. pulicaria biomass and clutch sizes along with greater H. shoshone fecundity. While these large-bodied, stress tolerant zooplankton taxa were relatively resilient to phenological shifts during the observation period, continued losses of ice cover may create unfavorably warm conditions and facilitate invasion by montane species, emphasizing the value of long-term data in assessing future changes to these sensitive ecosystems.

中文翻译：

---

高山浮游动物种群的物候学和湖泊结冰的重要性

高山湖泊固有的长时间冰盖给水生生物带来了独特的挑战，而最近冰盖的时间和持续时间的变化又加剧了这种挑战。为了了解高山浮游动物的反应，我们分析了十年（2009- 2019年）的水蚤（Daphnia pulicaria）和Hesperodiaptomus shoshone的开放水域样品的生长，繁殖和紫外线耐受性。由于类群之间的生殖差异，我们预期克隆枝角类动物相对于依赖于有性生殖的co足类动物，对冰盖变化表现出更快的反应。对于D. pulicaria，冰清除后的生物量和黑色素含量最低，整个夏季都增加，而冰融后不久的繁殖力最高。对于H. shoshone，生物量和繁殖力峰值随后出现，但随着时间的变化通常较小。多年来，结冰日期相差49天；较早的冰期和较长的生长期的多年，支持了D. pulicaria较高的生物量和离合器大小以及更大的H. shoshone繁殖力。虽然这些大的，耐压力的浮游动物类群在观察期内对物候变化相对有抵抗力，但冰盖的持续损失可能会产生不利的温暖条件并促进山地物种的入侵，从而强调了长期数据在评估未来变化中的价值这些敏感的生态系统。