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首页> 外文期刊>Freshwater science >Catchment topography and wetland geomorphology drivemacroinvertebrate community structure and juvenile salmoniddistributions in south-central Alaska headwater stream
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Catchment topography and wetland geomorphology drivemacroinvertebrate community structure and juvenile salmoniddistributions in south-central Alaska headwater stream

机译：阿拉斯加中南部源水流域的汇水区地形和湿地地貌驱动大型无脊椎动物群落结构和少年鲑鱼分布

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Conservation and management of headwater streams amid rapid global change require an understanding of the spatial and environmental factors that drive species distributions and associated ecosystem processes. We used a hierarchical analytical framework to model effects of catchment-scale topography and wetland geomorphic classes on stream physical habitat, chemistry, and macroinvertebrate and fish communities in 30 headwater streams across the Kenai Lowlands, southcentral Alaska, USA. We identified 135 macroinvertebrate taxa, 122 of which were aquatic insects, of which 79 were dipterans. We collected only 6 species of fish, but juvenile coho salmon and Dolly Varden were collected in 17 and 25 of the 30 streams and reached densities >500 and 1300/km, respectively. Flow-weighted slope, an indicator of water residence time and gradient, was the best catchment-scale correlate of macroinvertebrate and fish community structure, and its effect was mediated by wetland geomorphic classes and numerous water chemistry, substrate composition, and channel geomorphology variables measured at the reach scale. Many macroinvertebrate taxa showed high fidelity to different levels of the topographic gradient, resulting in high 13 diversity but relatively similar levels of a diversity across the gradient. Juvenile salmonids were segregated among streams by both species and age classes. Coho salmon fry and parr (<10 cm total length [TL]) had significant unimodal distributions that peaked in streams with intermediate slopes and gravel substrate, whereas presmolts ( ≥10 cm) were found only in lowest-sloping streams with mostly peat substrate and deep, slow channels. Large Dolly Varden ( ≥ 8 cm) were found across the entire gradient but were most abundant in high-sloping catchments, whereas small Dolly Varden (<8 cm) followed a similar distribution but were absent from the lowest-gradient sites with low flow velocity, dissolved O_2, and gravel substrate. Predictive modeling indicated that all of the 547 km of headwater streams in the study area might serve as potential habitat for ≥1 species and age class of salmonids. Our study should assist in development of catchment management tools for identifying and prioritizing conservation efforts in the region and may serve as a framework for other studies concerning biodiversity and focal species conservation in headwater streams.
机译：在全球快速变化的背景下，对源头水流的保护和管理需要了解驱动物种分布和相关生态系统过程的空间和环境因素。我们使用了层次分析框架来模拟集水区规模的地形和湿地地貌类别对横跨美国阿拉斯加中部Kenai低地的30条源头河流的河流物理栖息地，化学以及大型无脊椎动物和鱼类群落的影响。我们确定了135个大型无脊椎动物类群，其中122个是水生昆虫，其中79个是双翅类动物。我们仅收集了6种鱼类，但在30条溪流中的17条和25条中收集了幼年鲑和Dol​​ly Varden，其密度分别> 500和1300 / km。流量加权坡度是水停留时间和坡度的指标，是大型无脊椎动物和鱼类群落结构的最佳流域尺度相关性，其影响是由湿地地貌类别和许多水化学，底物组成和所测量的河道地貌变量所介导的在触及范围内。许多大型无脊椎动物分类单元对地形梯度的不同级别显示出较高的保真度，导致较高的13种多样性，但整个梯度上的多样性水平相对相似。幼鲑鱼类按物种和年龄分类隔离在溪流中。 Coho鲑鱼苗和parr（<10 cm总长[TL]）具有明显的单峰分布，在中等坡度和砾石基质的溪流中达到顶峰，而仅在最低倾斜度且泥炭基质和泥泞为主的溪流中才发现前蜕（≥10 cm）。较深，较慢的渠道。在整个坡度上发现大的多莉·瓦尔登（≥8 cm），但在高坡度集水区中最为丰富，而小的多莉·瓦尔登（<8 cm）遵循相似的分布，但流速低且梯度最低的地方则不存在，溶解的O_2和砾石基质。预测模型表明，研究区域内所有547 km的源头水流都可能成为≥1种和年龄类鲑鱼的潜在栖息地。我们的研究应协助开发集水区管理工具，以识别和优先考虑该地区的保护工作，并可以作为其他研究的框架，涉及有关上游水域生物多样性和重点物种保护的其他研究。

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