DATA for Hébert et al 2021b “Warming winters in lakes: Later ice onset promotes consumer overwintering and shapes springtime planktonic food webs”

NOTE: -Please use the latest version of the dataset. Additional updates may be made over time. -Details re. calculations, conversions, and units are provided in the Methods and Appendix of the paper.-Any questions can be directed at: [e-mail] ABSTRACT: Global climate warming is causing the loss of freshwater ice around the Northern Hemisphere. Although the timing and duration of ice covers are known to regulate ecological processes in seasonally ice-covered ecosystems, the consequences of shortening winters for freshwater biota are poorly understood owing to the scarcity of under-ice research. Here, we present one of the first in-lake experiments to postpone ice-cover onset (by ≤21 d), thereby extending light availability (by ≤40 d) in early winter, and explicitly demonstrate cascading effects on pelagic food web processes and phenologies. Delaying ice-on elicited a sequence of events from winter to spring: 1) relatively greater densities of algal resources and primary consumers in early winter; 2) an enhanced prevalence of winter-active (overwintering) consumers throughout the ice-covered period, associated with augmented storage of high-quality fats likely due to a longer access to algal resources in early winter; and 3) an altered trophic structure after ice-off, with greater initial springtime densities of overwintering consumers driving stronger, earlier top-down regulation, effectively reducing the spring algal bloom. Increasingly later ice onset may thus promote consumer overwintering, which can confer a competitive advantage on taxa capable of surviving winters upon ice-off; a process that may diminish spring food availability for other consumers, potentially disrupting trophic linkages and energy flow pathways over the subsequent open-water season. In considering a future with warmer winters, these results provide empirical evidence that may help anticipate phenological responses to freshwater ice loss and, more broadly, constitute a case of climate-induced cross-seasonal cascade on realized food web processes.注意事项：- 请使用该数据集的最新版本，后续可能会有额外更新。- 有关计算、转换及单位的详细说明，请参见论文的方法与附录章节。- 如有任何疑问，请联系：[e-mail] 摘要：全球气候变暖正导致北半球周边的淡水冰消退。尽管已知冰盖的形成时间与持续时长会调控季节性封冻水域生态系统的生态过程，但由于冰下研究（under-ice research）的匮乏，冬季时长缩短对淡水生物群落的影响仍未得到充分认知。本研究开展了首批原位湖泊实验之一，将封冰起始时间推迟至多21天，由此将初冬的光照可利用时长延长至多40天，并明确证实了其对浮游食物网（pelagic food web）过程与物候的级联效应。推迟封冻引发了从冬季到春季的一系列连锁反应：1）初冬时节藻类资源与初级消费者的密度相对更高；2）在整个封冰期内，越冬活跃消费者的占比显著提升，这大概率与初冬更长时间的藻类资源获取使得其优质脂肪储备增加有关；3）冰消（ice-off）后营养结构发生改变，越冬活跃消费者的春季初始密度更高，驱动了更强且更早的下行调控（top-down regulation），有效抑制了春季藻类水华（spring algal bloom）。因此，封冰起始时间愈发延后可能会促进消费者的越冬行为，这将为那些能够在冰消后存活的类群带来竞争优势；该过程可能会减少其他消费者在春季的食物可获得性，进而可能在后续的无冰期破坏营养联系与能量流动路径。在展望暖冬未来的背景下，本研究结果提供了实证依据，可帮助预测淡水冰消融引发的物候响应；更广泛而言，本研究还为气候诱导的跨季节级联效应作用于实际食物网过程提供了典型案例。