Habitat effects on stream productive capacity, energy flow, and adaptive tradeoffs among juvenile salmonids

鱼类成功地利用溪流生境的能力取决于物理生境结构、猎物产量以及捕食者和竞争者的丰度。这些特征形成了鲑鱼和鳟鱼等漂食性鱼类的适应性景观，同时限制了能量向鱼类营养级的转移。沿着水化学和温度，物理栖息地结构（如河道形态、流速、底质）仍然是河流生产力的最基本决定因素，了解鱼类生产的物理限制是预测栖息地变化对鱼类种群影响的关键。 这项建议的目的是i）发展一个一般的过程模式，有关生产的无脊椎漂流和少年漂流喂养鲑鱼（即太平洋鲑鱼和鳟鱼）流栖息地结构和流量，作为模拟栖息地和流量对幼鲑生产流的影响的定量框架; ii）通过实验确定在不同分类水平区分幼鲑的适应性权衡，特别强调理解生长分化的作用;和iii）评估对草食性鱼类分布的纬度限制是否影响能量流动和其他功能性摄食鱼类群体的生产，特别是漂食性鱼类（例如，幼鲑）。* 这项研究将提供i）一个新的合成的栖息地对生产和建模的无脊椎动物漂移和少年鲑鱼承载能力的影响; ii）显着的进展，在瞬时流科学，无论是在模型的开发，验证和识别的经验流量阈值; iii）提高理解的生理基础的适应性权衡，允许栖息地分区和共存沿着环境梯度;和iv）的一般性评估，潜在的原因，以及在流（草食动物）营养结构的大规模纬度倾斜的后果。这些代表了重要的贡献流，有机体和社区生态学的基本问题，并将提供直接应用，以改善濒危鱼类物种的管理，即时流，并在加拿大的栖息地恢复，潜在的影响范围从本地（濒危物种）到全球（改进即时流建模技术）。

The ability of fish to successfully exploit stream habitats depends on physical habitat structure, prey production, and the abundance of predators and competitors. These features form the adaptive landscape for drift-feeding fish like salmon and trout, while simultaneously constraining energy transfer to the fish trophic level. Along with water chemistry and temperature, physical habitat structure (e.g. channel form, velocity, substrate) remains the most fundamental determinant of stream productive capacity, and understanding physical constraints on fish production is key to predicting the effects of habitat change on fish populations.*** The objectives of this proposal are i) to develop a general process model relating production of invertebrate drift and juvenile drift-feeding salmonids (i.e. Pacific salmon and trout) to stream habitat structure and discharge, as a quantitative framework for modeling habitat and flow effects on juvenile salmonid production in streams; ii) to experimentally determine the adaptive tradeoffs differentiating juvenile salmonids at different taxonomic levels, with a particular emphasis on understanding the role of growth differentiation; and iii) to evaluate whether latitudinal constraints on herbivorous fish distribution affect energy flow and production of other functional feeding groups of fish, particularly drift-feeding fish (e.g., juvenile salmonids).*** This research will provide i) a novel synthesis of habitat effects on production and modeling of invertebrate drift and juvenile salmonid carrying capacity; ii) significant advances in instream flow science, both in terms of model development, validation, and identification of empirical flow thresholds; iii) improved understanding of the physiological basis of adaptive tradeoffs that allow habitat partitioning and co-existence along environmental gradients; and iv) an assessment of the generality, underlying causation, and consequences of large-scale latitudinal clines in stream (herbivore) trophic structure. These represent important contributions to fundamental issues in stream, organismal, and community ecology, and will provide direct application to improving management of endangered fish species, instream flows, and habitat restoration in Canada, with potential impacts ranging from local (endangered species) to global (improved instream flow modeling techniques).**