CAREER: Drought and metacommunity stability in riverine networks

在世界许多地区，干旱的频率、持续时间和严重程度都在增加。干旱会对河流生态系统产生负面影响——特别是当通常全年流动的河流变得断断续续时。气候干旱可以隔离河网的整个部分，并在大空间尺度上同步水生物丰度的波动。这些隔离和同步过程如何通过改变物种相互作用直接或间接危及水生物种，在很大程度上仍然未知。在这里，我建议通过结合长期监测和在Pinnacles国家公园间歇河网的实地实验，以及大规模的溪流生物多样性和水文数据建模来解决这一差距。该职业整合了研究和教育目标，并将为来自代表性不足背景的学生提供流传感器仪器，生物多样性采样和时间序列数据分析的实践经验。它还将创建一个生态干旱合作实验室，涵盖学术、政府和博物馆机构，研究与干旱有关的问题。尽管对淡水生物多样性对干旱的响应进行了大量研究，但仍然难以预测高水平生物组织（食物网和元群落）的响应。这主要是因为生物相互作用可以抑制或放大非生物压力对每个物种的影响。此外，干旱可能会削弱生物从其他来源分散和重新定居的能力（弹性战略家），或者在局部持续存在并在干燥事件后反弹的能力（抗性战略家）。通过结合跨越时空尺度和学科（元群落生态学、河流水文学、时间序列分析）的方法，研究者将确定干旱对元群落稳定性的净贡献。该项目的具体目标是：(i)了解河流中元群落稳定性的控制，重点关注干旱驱动的扩散限制和同步机制的研究相对较少；（二）确定近期气候干旱单独或与人类活动一起在多大程度上影响河网内和河网间的同步水流状况；（iii）预测美国河流无脊椎动物和鱼类对未来干旱的脆弱性，不仅考虑当地生物和非生物变化（温度和流量），还考虑栖息地组合和连通性的网络水平变化。这项工作将填补我们对树突网络中元群落动态机制理解的关键空白，并将有助于更好地量化在日益变化的气候下淡水生物多样性丧失的风险。针对本科生和研究生、保护从业者和公众的综合教育目标将促进对生物多样性如何在河网中持续存在的理解。通过对环境流动和栖息地恢复行动的稳健设计，这种认识的增加将改善保护结果。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The frequency, duration, and severity of droughts is increasing in many regions of the world. Drought can negatively impact riverine ecosystems—particularly if streams that generally flow year-round become intermittent. Climatic droughts can isolate entire portions of the river network, and synchronize fluctuations in abundance of aquatic organisms across large spatial scales. How these isolation and synchronization processes may endanger aquatic species directly, or indirectly by modifying species interactions, remains largely unknown. Here I propose to address this gap by combining long-term monitoring and field experiments in an intermittent river network in Pinnacles National Park, with large-scale modeling of stream biodiversity and hydrology data. This CAREER integrates research and education goals, and will provide students from underrepresented backgrounds with hands-on experience on stream sensor instrumentation, biodiversity sampling, and analysis of time-series data. It will also create an Ecological Drought Collaboratory spanning academic, government, and museum institutions researching drought-related questions.Despite much research on freshwater biodiversity responses to drought, it remains difficult to predict responses at high levels of biological organization (food webs and metacommunities). This is largely because biotic interactions can dampen or amplify impacts of abiotic stress on each species. Moreover, drought may erode the capacity of organisms to disperse and recolonize from other sources (resilience strategists), or to persist locally and bounce back after drying events (resistance strategists). Through a combination of approaches that span spatio-temporal scales and disciplines (metacommunity ecology, stream hydrology, time-series analysis), the investigator will determine the net contribution of drought to metacommunity stability. The specific goals of this project are: (i) understanding the controls of metacommunity stability in streams, with a focus on the relatively understudied mechanisms of drought-driven dispersal limitation and synchrony; (ii) determining to what extent recent climatic droughts, in isolation or in conjunction with human activities, synchronized flow regimes within and across river networks; and (iii) forecasting the vulnerability of U.S. stream invertebrates and fishes to future droughts, considering not only local biotic and abiotic change (temperature and flow) but also network-level shifts in habitat portfolio and connectivity. This work will fill a critical gap in our mechanistic understanding of metacommunity dynamics in dendritic networks, and will help better quantify risk of freshwater biodiversity loss under increasingly-variable climates. Integrated educational objectives targeting undergraduate and graduate students, conservation practitioners, and the public will promote understanding of how biodiversity persists in river networks. This increased understanding should improve conservation outcomes via robust design of environmental flows and habitat restoration actions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.