Interguild Interactions in Communities of Benthic Stream Invertebrates

这项研究的目的是测试一些长期存在但缺乏支持的关于温带溪流中无脊椎动物之间相互作用的假设。底栖溪流无脊椎动物群落包括几种不同的捕食策略的生物。“碎纸机”以大块的有机碎屑为食，比如枯叶和枯枝。“收集器”通过过滤水中的小有机颗粒来喂养。因为碎纸机在喂料时将较大的有机材料加工成小颗粒，所以人们普遍认为它们的存在有利于收集者（增加生长和/或存活率）。然而，最近的理论研究表明，这只是一种可能性。对碎屑的处理在短期内会产生颗粒，但也会去除以后可能产生颗粒的物质；因此，碎纸机的存在可能对收集者有害，特别是在较长的时间尺度上。在本研究中，将在爱荷华州东部的一条小溪中进行碎纸机密度的实验操作，以确定碎纸机-收集器相互作用的性质。这将是对碎纸机-收集器促进假说的第一次完整、直接的实地试验。第三类无脊椎动物被称为“食草动物”，它们通过从溪流表面刮取藻类为生。这些动物在进食时也会产生颗粒，也有人认为食草动物有助于收集器的生长或生存。这一假设将在碎纸机实验的同时用掠食器操作来验证。了解河流无脊椎动物之间的相互作用是很重要的，因为这些生物具有超越当地河流范围的生态和经济重要性。例如，研究的生物是水生和陆生动物的食物资源，包括鸟类、蝙蝠，以及经济上重要的鱼类，如鳟鱼和鲑鱼。一些收集者（黑蝇）是野生动物和牲畜的重要病虫害媒介。最后，这些无脊椎动物被广泛用于评估和管理溪流水质。这项研究的结果将增加对物种之间相互作用的理解，这些物种是这一重要自然群落的核心。

9628969 Heard The goal of this research is to test some long-standing but poorly supported hypotheses about interactions among invertebrates inhabiting temperate streams. Communities of bottom-dwelling stream invertebrates include organisms with several different feeding strategies. "Shredders" feed on large pieces of organic detritus, such as dead leaves and twigs. "Collectors" feed by filtering small organic particles from the water. Because shredders process larger organic material to small particles as they feed, it has been widely assumed that their presence benefits collectors (increases growth and/or survival). However, recent theoretical work suggests that this is only one possibility. Processing of detritus produces particles in the short term, but also removes material that could yield particles later; therefore, the presence of shredders might be detrimental to collectors, particularly over longer time scales. In the present study, experimental manipulations of shredder densities in natural and artificial streams will be conducted to determine the nature of the shredder-collector interaction in a small stream in eastern Iowa. These will be the first complete, direct field tests of the shredder-collector facilitation hypothesis. A third group of invertebrates, called "grazers", feed by scraping algae from surfaces in streams. These animals also produce particles as they feed, and it has also been assumed that grazers facilitate collector growth or survival. This hypothesis will be tested with grazer manipulations in parallel with the shredder experiments. Understanding interactions among stream invertebrates is important because these organisms have ecological and economic importance beyond the local stream reach. For instance, the study organisms are food resources for aquatic and terrestrial animals including birds, bats, and economically important fish species such as trout and salmon. Some collectors (blackflies) are important pests and disease vectors for wildlife and livestock. Finally, these invertebrates are widely used in assessing and managing stream water quality. Results from this study will increase understanding of interactions among species that are central to this important natural community.