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着泥沙侵蚀，加剧了世界上的许多环境问题。在淡水栖息地，在明确将生物学和地貌学联系起来解决环境问题方面取得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中。这项研究项目调查了溪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干扰。沉积物侵蚀是淡水生态系统中的一个关键变量，因为它影响淡水生物多样性、昆虫和鱼卵的生存，改变藻类的组成和活动，并改变碳循环和营养循环。对沉积物侵蚀的了解，包括海底动物的影响，将解决一系列与社会有关的实际问题，包括提供预测土地利用改变的地貌侵蚀的模型，预测由于气候变暖和农业改道引起的世界各地水位变化引起的洪水的影响，以及保护和恢复鱼类等受威胁淡水生物的栖息地。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，向高中教师讲授与海底无脊椎动物对沉积物侵蚀的影响相关的概念，并制作记录沉积物侵蚀的外展视频。为了调查溪流中的动物如何影响对洪水干扰的身体抵抗力，从而对水生底栖动物群落和生态系统过程产生影响，研究人员将研究常见的水生生态系统工程师--网织水栖类线虫幼虫(毛翅目：水虫科)。这些水生昆虫建造的丝状结构可以将河床沉积物结合在一起，增加移动沉积物所需的力量，并减少推移质流量。研究人员将量化身体幼虫从谷物到景观尺度的稳定泥沙的效果。他们还将记录由于蚯蚓丝结构引起的沉积物扰动的变化如何影响生态系统生产力、营养循环和洪水后底栖群落的恢复。研究人员将结合受控实验室实验、天然溪流中的卡迪蝇密度控制、实地调查和沉积物运输模型来确定卡迪蝇生态系统工程如何影响景观中的泥沙输送状况。总之，这一系列研究将量化这些丰富的生态系统工程师能够在多大程度上调节溪流的侵蚀过程。

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.