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--特别是如果通常全年流动的溪流变得断断续续的话。气候干旱可以隔离河网的整个部分，并在大的空间尺度上同步水生生物丰度的波动。这些隔离和同步过程如何通过改变物种之间的相互作用直接或间接地危及水生物种，在很大程度上尚不清楚。在这里，我建议通过在尖顶国家公园的间歇性河流网络中进行长期监测和实地试验，以及对河流生物多样性和水文数据进行大规模建模来解决这一差距。这一职业结合了研究和教育目标，将为来自代表性不足背景的学生提供有关水流传感器仪器、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，横跨学术、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反应进行了大量研究，但仍然很难预测高水平的生物组织(食物网和集合群落)的反应。这在很大程度上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，干旱可能会侵蚀生物体从其他来源分散和重新定居的能力(复原力策略师)，或者在干旱事件发生后在当地持续并反弹的能力(抗性策略师)。通过结合时空尺度和学科(元社区生态学、河流水文学、时间序列分析)的方法，调查者将确定干旱对元社区稳定的净贡献。该项目的具体目标是：(I)了解河流中集合群落稳定性的控制，重点是相对较少研究的干旱驱动的扩散限制和同步机制；(Ii)确定最近的气候干旱在多大程度上孤立地或与人类活动相结合，在河流网络内和河流之间同步流动；以及(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枝状网络中的元群落动态的机械性理解的一个关键空白，并将有助于更好地量化在日益多变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流网络中持续存在的理解。这个奖项反映了NSF的法定使命，通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为是值得支持的。

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.