Collaborative Research: Evaluating Species Redundancy in Stream Detrital Processing

9707500 Covich森林集水区水源中的营养动物主要从河岸凋落叶输入中获取能量和营养。在切碎和刮落叶的过程中，它们将微生物条件下的叶子转化为下游悬浮饲料使用的有机颗粒。本提案将探讨以下问题。在这个过程中，是否有一些腐食物种起着重要的作用？在确定叶片加工和向下游消费者出口悬浮微粒的速度时，其他物种是否多余？一种或多种腐食动物的消失可能会改变河流生态系统中的叶片加工过程，但河流生态学家缺乏一种经验的、基于河流的方法来确定物种是否在凋落叶处理过程中具有独特的作用，或者它们的相互作用对其他腐食动物是否重要。如果腐植物种是多余的，并且在凋落叶处理中没有相互作用或独特的物种特异性作用，那么一个或多个物种的损失将不会影响总体处理速度。另外，如果某些底栖动物具有关键功能，那么随着这些物种的消失或被替换，河流凋落叶处理速率将会降低。这项研究将确定不同的营养物质物种是否相互独立，作为替代品或替代品，以消极的，抑制的方式，还是以积极的，促进的方式发挥作用。在孤立的溪流中进行的研究结果将为Luquillo LTER站点正在进行的叶凋落物处理研究中不同种类的腐食动物的跨站点比较提供数据。此外，本研究将提供深入了解引入物种对生态系统功能的影响，并将其与明显相似的本地物种的功能作用进行比较。

9707500 Covich Detritivores in headwater streams of forested catchments obtain their energy and nutrients primarily from riparian leaf litter input. In the process of shredding and scraping leaf litter they transform microbially conditioned leaves into organic particulates used by downstream suspension feeders. This proposal will investigate the following questions. Do some detritivore species play essential roles in this processing? Are other species redundant in determining the rate of leaf processing and export of suspended particulates to downstream consumers? The loss of one or more detritivore species may alter leaf processing in fluvial ecosystems, yet stream ecologists lack an empirical, stream-based approach for determining if species have unique roles in leaf litter processing or if their interactions are important to other detritivores. The loss of one or more species will not influence overall rates of processing if detritivore species are redundant and have no interactive or unique species-specific role in leaf-litter processing. Alternatively, rates of instream leaf-litter processing will decrease with the loss or replacement of certain benthic detritivore species if these species perform key functions. This research will determine if different detritivore species function either independently of each other, as substitutes or replacements for one another, in a negative, inhibitory manner, or in a positive, facilitative manner. Results of this research in isolated streams will provide data for cross-site comparisons among different species of detritivores from on-going studies of leaf-litter processing at the Luquillo LTER site. In addition, this research will provide insight into the effects of introduced species on ecosystem function in comparison to the functional role on apparently similar, native species.