NSFDEB-NERC: Warming's silver lining? Thermal compensation at multiple levels of organization may promote ecosystem stability in response to drought

我们拟议的研究的目标是了解河流生态系统的长期变暖如何影响它们对日益普遍的水文干旱和日益严重的水文干旱的反应(即抵抗力和恢复力)。人类活动产生的人为温室气体排放正在导致全球气温上升以及极端气候事件的频率和强度增加。虽然已知这些驱动因素的变化会单独影响自来水的结构和功能，但很少有研究调查它们的组合或相互作用的影响。普遍的观点是，气候变暖和干旱结合在一起，将产生比任一种压力单独造成的更极端的生态后果。然而，新出现的证据表明，气候变暖可能会引发“补偿性”反应--包括适应性反应和生态反应--这可能会减轻极端干旱的影响。我们的NSFDEB-NERC合作项目将结合实验室测量(冰岛大学)、河流中观温度和干旱操纵(英国伯明翰大学)和全程干旱操纵(冰岛亨吉尔地热集水区)来测试总体假设，即长期变暖增强河流生态系统稳定性(包括抗旱性和恢复力)以应对干旱事件。我们的第一个目标集中在个体层面，调查对气候变暖的生理适应是否会影响无脊椎动物的碳利用效率，以及它们在抗旱和恢复中的作用。我们的第二个目标试图量化整个无脊椎动物群落及其生物量生产在自然和实验温度梯度上对干旱的抵抗力和弹性。我们的最终目标将通过研究气候变暖导致的养分供应和初级生产者的变化如何影响生态系统新陈代谢和氮吸收的稳定性来探索生态系统层面补偿反应的潜力，以应对干旱。

The goal of our proposed research is to understand how long-term warming of stream ecosystems influences their response (i.e., resistance and resilience) to increasing prevalence and intensity of hydrologic drought. Anthropogenic greenhouse gas emissions from human activities are generating both a rise in global temperatures and an increase in the frequency and intensity of extreme climatic events. While shifts in these drivers are known to affect the structure and function of running waters separately, few studies have investigated their combined or interactive effects. The prevailing view is that warming and drought will combine to produce more extreme ecological consequences than would result from either stressor alone. Yet, emerging evidence suggests that warming may trigger 'compensatory' responses - both adaptive and ecological - that may have the potential to lessen the impacts of extreme drought. Our collaborative NSFDEB-NERC project will combine laboratory measurements (University of Iceland), stream mesocosm manipulations of temperature and drought (University of Birmingham, U.K.), and whole-reach drought manipulations (Hengill geothermal catchment, Iceland) to test the overarching hypothesis that long-warming enhances stream ecosystem stability (both resistance and resilience) in response to drought events. Our first objective is focused at the individual level, investigating whether physiological adaptations to warming influence invertebrate carbon use efficiencies and their role in drought resilience and recovery. Our second objective seeks to quantify resistance and resilience of entire invertebrate communities and their biomass production in response to drought across natural and experimental thermal gradients. Our final objective will explore the potential for ecosystem-level compensatory responses by examining how warming-induced shifts in nutrient supply and primary producers influence stability of ecosystem metabolism and nitrogen uptake in response to drought.