Both fine‐ and coarse‐scale physicochemical conditions affect the quantity and quality of nursery habitats within riverine ecosystems. Nursery habitats in large, braided, and sandbed streams such as the lower Red River of Oklahoma, Texas, and Arkansas are not well described and likely vary among species. Identification of nursery habitats is important for developing proper conservation and management actions. We used an occupancy model framework to determine how hierarchical habitat factors related to the occupancy of 38 juvenile fish species. Our findings indicate that large river nursery habitats can generally be defined by reaches with off‐channel slackwater habitat, having deep pools but shallow thalweg depths, typically located further away from dams, and with low percentages of limestone lithology. Species within the same genera often exhibited variable relationships with river slope, amount of large woody debris, channel shape, discharge, and position of reaches within the stream network. Our results indicate important species‐specific relationships that define nursery habitats, indicating an important context dependency of nursery habitats even within fishes that are taxonomically similar. If the goal is to improve recruitment by native fishes, then consideration of the important species‐specific differences would be beneficial if improvements are made to nursery habitats. Moreover, careful consideration of the effects of dam operations will help maintain proper connectivity to off‐channel habitats important in downriver portions of the river network.

中文翻译：

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评估红河下游流域大型河流鱼类育苗生境的环境依赖性

精细和粗略的物理化学条件都会影响河流生态系统内苗圃栖息地的数量和质量。大型辫状河床和沙床溪流（例如俄克拉荷马州、德克萨斯州和阿肯色州的红河下游）的苗圃栖息地尚未得到很好的描述，并且可能因物种而异。确定苗圃栖息地对于制定适当的保护和管理行动非常重要。我们使用占用模型框架来确定分层栖息地因素与 38 种幼鱼物种的占用之间的关系。我们的研究结果表明，大型河流育苗生境通常可以由具有河道外滞水生境的河段来定义，这些河段具有深水池但浅海深度，通常距离水坝较远，石灰岩岩性比例较低。同一属内的物种经常表现出与河流坡度、大型木本碎片数量、河道形状、流量和河网内河段位置的可变关系。我们的结果表明，定义育苗栖息地的重要物种特异性关系，表明即使在分类学相似的鱼类中，育苗栖息地也存在重要的环境依赖性。如果目标是改善本地鱼类的补充，那么如果改善苗圃栖息地，考虑重要的物种特异性差异将是有益的。此外，仔细考虑大坝运营的影响将有助于保持与河网下游部分重要的河道外栖息地的适当连通性。