The effect of habitat structure on trophic level transfer efficiency and adaptive tradeoffs by juvenile salmonids

物理栖息地结构是一个关键的生态系统属性，影响基础系统生产力和能量转移到更高的营养水平。尤其是在河流和溪流中，不同种类的幼鲑似乎已经进化出不同的适应物理栖息地的极端沿着环境梯度有关的流坡度，速度和基板的大小。尽管对幼鲑栖息地关系进行了广泛的研究，但对栖息地结构制约漂食性鱼类适应和生产的机制仍然知之甚少。最常用的模型，用于评估流量和栖息地对生产能力的影响流是基于相关的栖息地适宜性曲线的关系，这是有限的，在其预测能力，有必要为一个更机械的方法来模拟鱼类生产流。我们提出了一系列的实验，将严格评估的影响，物理栖息地i）适应性的限制漂流喂养的鱼，ii）转移效率的能量，鱼类营养水平沿着纵向下游梯度，和iii）自下而上的影响，通过增加生产的无脊椎动物猎物介导的鱼类生产的栖息地结构。将在天然和人工河道中进行研究，并将能够评估不同生境配置影响漂食鱼类产量的潜在机制。从这些实验中获得的数据将被用来开发和parameterized一个通用的生物能量模型，将有广泛的应用在流渔业生态作为一种新的研究/管理工具，用于预测栖息地，温度，流量和猎物丰度的变化对幼鲑生产能力的影响。总的来说，这些信息将被用来告知流栖息地管理和保护活动，面对人类发展，并指导和优化退化河流的恢复。

Physical habitat structure is a key ecosystem attribute that influences both basal system productivity and the transfer of energy to higher trophic levels. This is especially true in rivers and streams, where different species of juvenile salmon appear to have evolved divergent adaptations to physical habitat extremes along environmental gradients related to stream slope, velocity, and substrate size. Despite extensive research on juvenile salmon habitat relationships, the mechanisms whereby habitat structure constrains adaptations and production of drift-feeding fish remain poorly understood. Most commonly used models for assessing the effects of flow and habitat on productive capacity in streams are based on correlative Habitat Suitability Curve relationships, which are limited in their predictive ability, and there is a need for a more mechanistic approach to modeling fish production in streams. We propose a series of experiments that will rigorously evaluate the effects of physical habitat on i) adaptive constraints for drift-feeding fish, ii) transfer efficiency of energy to the fish trophic level along a longitudinal downstream gradient, and iii) bottom-up effects of habitat structure on fish production mediated through increased production of invertebrate prey. Research will be carried out in both natural and artificial stream channels, and will permit assessment of the underlying mechanisms whereby different habitat configurations affect production of drift-feeding fish. Data from these experiments will be used to develop and parameterize a general bioenergetic model that will have broad application in stream fisheries ecology as a novel research/management tool for predicting the effects of changes in habitat, temperature, flows, and prey abundance on juvenile salmon productive capacity. Collectively, this information will be used to inform stream habitat management and conservation activities in the face of human development, and to guide and optimize restoration of degraded streams.