Habitat degradation, organismal needs, and other effects influencing freshwater mussel declines have been subject to intense focus by conservationists for the last thirty plus years. While researchers have studied the physical habitat requirements and needs of mussels in small- to medium-sized rivers with variable levels of success, less research has been conducted on mussel habitat in larger non-wadeable rivers, especially at the reach scale, where core flow environmental conditions provide and maintain habitat for freshwater mussels. We designed a quasi-experimental observational field study to examine seven hydrologic energy and material variables laterally and longitudinally at Current and Extirpated mussel bed habitat reaches in lower White River, Arkansas, a large non-wadeable, sand-bed-material-dominated river. As expected, lateral and longitudinal hydrologic variable differences were identified within a reach. Mean velocity, bed velocity, the Froude number, and stream power were all significantly lower at Current mussel bed habitat stations within a sampling reach. Energy regime differences in shear stress and, marginally, stream power were higher at Extirpated mussel bed habitat reaches. Several factors emerged as important to mussel habitat in the White River. First, bed velocity warrants further exploration in terms of both flow strength and flow direction. Second, bedload appears to be the primary contributor to mussel habitat but requires additional exploration within the context of core and secondary flow pathway interactions. The combined empirical evidence from our study supports the flow refugium concept identified for mussel habitats in smaller systems but expands the concept to large non-wadeable streams and includes reach-scale refuge from sediment transport conditions.

中文翻译：

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冲积砂床-材料为主的大河中的淡水贻贝栖息地：核心流沉积物避难所？

在过去的三十多年中，环境保护主义者一直强烈关注栖息地的退化，生物需求以及其他影响淡水贻贝下降的影响。尽管研究人员研究了成功水平不一的中小河流贻贝的物理生境需求和需求，但对大型非河川河流中的贻贝生境进行的研究较少，特别是在核心流量最大的河段环境条件为淡水贻贝提供并维持栖息地。我们设计了一个准实验性观察野外研究，以横向调查和纵向调查七个水文能量和物质变量，这些水文能量和物质变量位于阿肯色州下怀特河下游，这是一条大型的无人值守，以砂层材料为主的河流。不出所料 在可及范围内确定了横向和纵向水文变量的差异。在采样范围内，当前贻贝河床栖息地站的平均速度，河床速度，弗洛德数和河流功率均显着降低。在已灭绝的贻贝栖息地河段，剪切应力和流动力的能级差异较高。对于怀特河的贻贝栖息地来说，有几个因素变得很重要。首先，床速需要在流动强度和流动方向两方面进行进一步的探索。其次，床头负荷似乎是贻贝栖息地的主要贡献者，但需要在核心和次要流动途径相互作用的背景下进行额外的勘探。