Variation in the Strength of Cascading Trophic Interactions Across a Riverscape

由于全球变化和人类对水的使用，河流的自然流态正在发生重大变化。这项研究将有助于理解水流的自然变化如何影响河流生态系统的功能。在受水流影响的河流中，昆虫幼虫对藻类的捕食是一种基本的重要相互作用。在一些溪流中，大量的藻类是由“营养瀑布”造成的，在这种情况下，像鲑鱼这样的捕食者会抑制捕食，从而导致藻类的增加。在其他溪流中，昆虫捕食者能够控制藻类。洪水和干旱等极端事件会影响食草动物的丰度和类型、鲑鱼的数量、藻类的生长速度和营养物质的可获得性，从而影响食草动物和藻类的相互作用。流态变化对食草动物-藻类相互作用的影响将在河流-地貌上进行测量，以揭示对营养瀑布强度的控制。这项工作侧重于许多生态系统的基本物种相互作用；因此，它将有助于产生广泛适用的生态一般性。此外，该项目还建立在对科罗拉多州西部落基山生物实验室附近的东河谷溪流长达30年的研究基础上。与世界上许多其他地区一样，水资源的命运在科罗拉多州西部引发了激烈的辩论。这项研究将加深人们对河势自然变化对河流居民影响的了解，从而为人类引起河流流量变化的河流管理提供有价值的知识。

Natural flow regimes of rivers are undergoing considerable modification due to global change and human use of water. This research will contribute to understanding how natural variation in flow influences the function of river ecosystems. The grazing of algae by insect larvae is a fundamentally important interaction in rivers that is affected by the flow regime. In some streams large amounts of algae result from 'trophic cascades' whereby predators like trout suppress grazing leading to increases in algae. In other streams insect grazers are able to keep algae in check. Extreme events like floods and droughts can influence grazer-algal interactions by affecting the abundance and type of grazers, numbers of trout, algal growth rates, and availability of nutrients. The effects of variation in flow regimes on grazer-algal interactions will be measured across a river-landscape to unravel the controls on the strength of trophic cascades. This work focuses on species interactions fundamental to many ecosystems; thus it will contribute to producing broadly applicable ecological generalities. Furthermore, the project builds on 30 years of research on streams in the East River valley near the Rocky Mountain Biological Laboratory in Western Colorado. The fate of water resources is hotly debated in Western Colorado, like many other areas around the world. By advancing understanding of the effects of natural variation in flow regimes on river inhabitants, the research will provide knowledge valuable for the management of rivers with human-induced changes to river flow.