Understanding trade-offs associated with occupying various aquatic habitats provides a mechanistic understanding of habitat needs that can be used to evaluate the consequences of habitat loss or alteration. We used instream enclosures and field observations to identify how velocity affects the growth rates of four native species in the upper Gila River basin: longfin dace (Agosia chrysogaster) and speckled dace (Rhinichthys osculus), two species of no conservation concern, and loach minnow (Tiaroga cobitis) and spikedace (Meda fulgida), two federally endangered species. Elevated velocity was predicted to increase food delivery through drift or stimulation of benthic primary production. Energetic costs of high-velocity habitat were predicted to vary with morphology and behaviour and be lowest for speckled dace and loach minnow because they are adapted to occupy interstitial spaces of the substrate in riffles. Spikedace and longfin dace should perform best in moderate velocities, where the trade-off between exposure to drifting macroinvertebrates outweighs the energetic costs of maintaining position in the water column. Growth rates of loach minnow and speckled dace increased in higher velocities, but contrary to our initial predictions, spikedace growth rates also increased in high-velocity habitats while longfin dace grew fastest in low-velocity habitats; similar to the locations these species occupied based on field observations. These results indicate that for spikedace, the increased abundance of drifting macroinvetebrates in high-velocity habitats outweighs the energy expenditure, but for longfin dace the energetic costs of occupying moderate to high-velocity habitats outweigh the benefit to increased food availability. Our experiment provides a mechanistic understanding of habitat requirements across species and may inform predictions on how modifications or restoration of riverine ecosystems influence native fish diversity.

中文翻译：

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太快有多快？水流速度对四种吉拉河本地鲤科鱼的生长产生不同影响

了解与占用各种水生栖息地相关的权衡提供了对栖息地需求的机械理解，可用于评估栖息地丧失或改变的后果。我们使用河内围场和实地观察来确定速度如何影响吉拉河流域上游四种本地物种的生长速度：长鳍鲮鱼 ( Agosia chrysogaster ) 和斑点鲮鱼 ( Rhinichthys osculus )，这两种没有保护问题，还有泥鳅鲦鱼( Tiaroga cobitis ) 和尖刺鱼 ( Meda fulgida)，两种联邦濒危物种。预计提高的速度会通过漂移或刺激底栖初级生产来增加食物输送。据预测，高速栖息地的能量成本会随形态和行为而变化，并且对于斑点鲮鱼和泥鳅鲦鱼来说是最低的，因为它们适应于在浅滩中占据基质的间隙空间。尖刺鲮鱼和长鳍鲮鱼应该在中等速度下表现最佳，在这种情况下，暴露于漂流的大型无脊椎动物之间的权衡超过了在水柱中保持位置的能量成本。泥鳅鲦鱼和斑鲮的增长率在较高的速度下增加，但与我们最初的预测相反，尖刺鲮在高速栖息地的增长率也增加了，而长鳍鲮在低速栖息地的生长速度最快；类似于这些物种根据实地观察所占据的位置。这些结果表明，对于尖刺鲮来说，在高速栖息地中增加的漂流大型无脊椎动物的数量超过了能量消耗，但对于长鳍鲮来说，占据中速到高速栖息地的能量成本超过了增加食物供应的好处。我们的实验提供了对跨物种栖息地要求的机械理解，并可能为预测河流生态系统的修改或恢复如何影响本地鱼类多样性提供信息。但对于长鳍鲮来说，占据中速到高速栖息地的能源成本超过了增加食物供应所带来的好处。我们的实验提供了对跨物种栖息地要求的机械理解，并可能为预测河流生态系统的修改或恢复如何影响本地鱼类多样性提供信息。但对于长鳍鲮来说，占据中速到高速栖息地的能源成本超过了增加食物供应所带来的好处。我们的实验提供了对跨物种栖息地要求的机械理解，并可能为预测河流生态系统的修改或恢复如何影响本地鱼类多样性提供信息。