Collaborative Research: Sediment stabilization by animals in stream ecosystems: consequences for erosion, ecosystem processes, and biodiversity

生物和物理条件的变化共同影响沉积物侵蚀，使世界上的许多环境问题更加恶化。在淡水栖息地，将生物学和地貌学明确地联系起来以解决环境问题的主要进展包括将生活在溪流中的许多小动物的作用纳入我们对侵蚀的理解。本研究旨在探讨河流中的底栖无脊椎动物如何通过调节河床的稳定性来影响洪水扰动。泥沙侵蚀是淡水生态系统的一个关键变量，因为它影响淡水生物多样性、昆虫和鱼卵的存活，改变藻类的组成和活动，并改变碳和养分循环。对沉积物侵蚀的理解，包括对底栖动物的影响，将解决一系列与社会相关的实际问题，包括为预测土地利用改变的景观侵蚀的模型提供信息，预测由于气候变暖和农业转移引起的水位变化而在全球范围内改变的洪水的影响，以及保护和恢复受威胁的淡水生物（如鱼类）的栖息地。该项目将为一名博士生、两名硕士生和四名本科生提供研究机会，开展研讨会，向高中教师讲授有关海底无脊椎动物对沉积物侵蚀影响的概念，并制作记录沉积物侵蚀的外延视频。为了研究河流中的动物如何影响水生底栖生物群落和生态系统过程对洪水干扰的物理抵抗力，研究人员将研究常见的水生生态系统工程师，织网水心虫caddisfly幼虫（毛翅目：水心虫科）。这些水生昆虫建造的丝状结构可以将河床沉积物粘在一起，增加移动沉积物所需的力，并减少河床通量。研究人员将量化从谷物到景观尺度的球蝇幼虫对沉积物稳定的影响。他们还将记录由于球蝇丝结构引起的沉积物扰动变化如何影响生态系统生产力、养分循环和洪水后底栖生物群落的恢复。研究人员将结合控制实验室实验、自然溪流中的球蝇密度操纵、实地调查和沉积物运输模型来确定球蝇生态系统工程如何影响景观中的沉积物运输制度。总之，一系列的研究将量化这些丰富的生态系统工程师对河流侵蚀过程的调节作用。

Many of the world's environmental problems are exacerbated by changes in both biological and physical conditions that jointly influence sediment erosion. In freshwater habitats, major progress toward clearly linking biology and geomorphology to address environmental problems includes incorporating the role of the many small animals that live in streams into our understanding of erosion. This research project investigates how bottom-dwelling invertebrates in streams influence flood disturbance by regulating the stability of the riverbed. Sediment erosion is a critical variable in freshwater ecosystems because it influences freshwater biodiversity, insect and fish egg survival, changes the composition and activity of algae, and alters carbon and nutrient cycling. An understanding of sediment erosion that includes the impacts of bottom-dwelling animals will address a range of practical problems relevant to society, including informing models to predict erosion in landscapes altered by land use, predicting the impacts of floods that are being altered worldwide as a result of changes to water levels caused by climate warming and diversion for agriculture, and protecting and restoring habitat for threatened freshwater organisms such as fish. This project will provide research opportunities for one PhD student, two Master students, and four undergraduate students, develop workshops to teach concepts related to bottom-dwelling invertebrate influences on sediment erosion to high school teachers, and produce outreach videos documenting sediment erosion.To investigate how animals in streams influence physical resistance to flood disturbance with consequences for aquatic benthic communities and ecosystem processes, the researchers will study common aquatic ecosystem engineers, web-spinning hydropsychid caddisfly larvae (Trichoptera:Hydropsychidae). These aquatic insects build silk structures that can bind riverbed sediment together, increase the force required to move sediments, and reduce bedload flux. The researchers will quantify sediment stabilization effects by caddisfly larvae from grain to landscape scales. They will also document how changes in sediment disturbance due to caddisfly silk structures influence ecosystem productivity, nutrient cycling, and the recovery of benthic communities following floods. The researchers will use a combination of controlled laboratory experiments, caddisfly density manipulations in natural streams, field surveys, and sediment transport models to identify how caddisfly ecosystem engineering affects sediment transport regimes across landscapes. Together, the series of studies will quantify how much these abundant ecosystem engineers can regulate erosional processes in streams.