Dissertation Research: Effects of Omnivorous Fishes and Shrimps on Community Structure Along a Tropical Stream Continuum, Puerto Rico

9701299普林格尔热带溪流的典型特征是丰富的杂食性鱼类和虾;然而，对这些大型消费者在构建溪流群落中的相对作用知之甚少。这些物种通常有迁徙的生命周期，在其一生中栖息在低地和源头。从下游抽取大量的水，导致这些生物群的直接死亡，并改变其分布和丰度。拟议的研究将确定鱼类和虾对波多黎各东北部圣埃斯皮里图连续体沿着底栖生物群落结构的影响。 本研究将探讨以下问题：（1）杂食性鱼虾是否显著影响沉积物累积模式（即底栖沉积环境）？(2)排除杂食性鱼虾后会发生营养级联吗？（3）鱼虾的影响如何沿河流连续体沿着变化？鱼和虾对昆虫，藻类资源和沉积物积累的影响将通过操纵它们的存在和不存在在三个站点沿着河流连续使用原位电封闭技术进行实验研究。建议的研究将提供信息的杂食性的作用，在构建一个热带流社区，并将扩大我们以前的研究的影响，鱼类和虾叶分解，包括其对初级生产者，沉积和社区结构沿着河流连续体的影响。这项研究还将提高我们预测这些受威胁的河流生态系统如何应对人为干扰的能力。

9701299 Pringle Tropical streams are typically characterized by an abundance of omnivorous fishes and shrimps; however little is known about the relative roles of these macroconsumers in structuring stream communities. These species typically have migratory life cycles, inhabiting both lowlands and headwaters during their lifetime. High levels of water withdrawal from lower stream reaches are resulting in direct mortality of these biota and changes in their distribution and abundance. Proposed research will determine the effects of fishes and shrimps on benthic community structure along the continuum of the Rio Espiritu Santo in northeastern Puerto Rico. In this study, the following questions will be addressed: (1) Do omnivorous fishes and shrimps significantly affect patterns of sediment accrual (i.e. the benthic depositional environment)?; (2) Do trophic cascades occur when omnivorous fishes and shrimps are excluded? and (3) How do effects of fishes and shrimps vary along the stream continuum? Effects of fishes and shrimps on insects, algal resources, and sediment accrual will be experimentally examined by manipulating their presence and absence at three sites along the river continuum using an in situ electric exclosure technique. Proposed research will provide information on the role of omnivory in structuring a tropical stream community and will expand our previous studies of effects of fishes and shrimps on leaf decomposition to include their effects on primary producers, sedimentation, and community structure along the river continuum. This research will also enhance our ability to predict how these threatened stream ecosystems respond to anthropogenic disturbance.