Data from: Summer stream temperatures influence sculpin distributions and spatial partitioning in the Upper Clark Fork River Basin, Montana

The upper Clark Fork River basin of western Montana supports a poorly understood sculpin (Uranidea spp.) fauna that has perplexed ichthyologists and fish ecologists since the late 1800s. During our study, the basin contained three sculpin taxa whose taxonomy was under revision. All three taxa were formerly referred to the genus Cottus but are now treated as Uranidea. Our goal was to improve understanding of the distribution and ecology of two of the taxa. From 2006 to 2009, we sampled 144 reaches in 31 streams and rivers to determine distributions of each taxa across the study area and within streams. We collected habitat data in 2007 and stream temperature data from 2006–2009 to identify correlates of sculpin distributions. In streams where both taxa occurred, Rocky Mountain Sculpin Uranidea sp. cf. bairdii were downstream and Columbia Slimy Sculpin U. sp. cf. cognata were upstream with a syntopic zone in between. Summer stream temperatures strongly influenced sculpin distributions, with mean August 2007 water temperatures increasing in order of reaches characterized as: Columbia Slimy Sculpin-dominated, syntopic, Rocky Mountain Sculpin-dominated, and no sculpin. Columbia Slimy Sculpin occurred in cold tributaries of the Blackfoot, Clark Fork, and Bitterroot rivers and in two coldwater refugia in the mainstem Bitterroot River. In contrast, Rocky Mountain Sculpin occupied warmer downstream segments of many Blackfoot and Clark Fork river tributaries as well as some mainstem reaches of both rivers but were absent from the Bitterroot River drainage. Persistence of the taxa will likely depend, both directly and indirectly, on future water temperatures, and thus, sculpins are appropriate targets for researching and monitoring biological changes resulting from climate change.

蒙大拿州西部的克拉克福克河上游流域分布着一类尚未被充分认知的杜父鱼（sculpin）类群（Uranidea spp.），自19世纪末以来，该类群便一直困扰着鱼类学家与鱼类生态学家。本研究涉及的流域内共有3个杜父鱼分类单元，其分类学地位正处于修订阶段。该3个分类单元此前均被归入杜父鱼属（Cottus），如今则被重新划分至乌拉杜父鱼属（Uranidea）。本研究旨在加深对其中2个分类单元的分布与生态特征的认知。2006年至2009年间，我们对31条溪流与河流的144个河段开展采样调查，以明确各分类单元在研究区域及溪流内部的分布格局。我们于2007年采集生境数据，并在2006至2009年间持续监测溪流水温，以解析影响杜父鱼分布的相关因子。在两个分类单元均有分布的溪流中，落基山杜父鱼（Uranidea sp. cf. bairdii）分布于下游区段，哥伦比亚黏滑杜父鱼（U. sp. cf. cognata）分布于上游区段，二者之间存在一段同域分布带。夏季溪流水温对杜父鱼的分布具有显著调控作用：2007年8月的平均水温按河段类型依次升高，排序为：以哥伦比亚黏滑杜父鱼为优势类群的河段、同域分布河段、以落基山杜父鱼为优势类群的河段，以及无杜父鱼分布的河段。哥伦比亚黏滑杜父鱼栖息于布莱克富特河（Blackfoot River）、克拉克福克河与比特鲁特河（Bitterroot River）的寒冷支流中，同时也见于比特鲁特河干流的两处冷水避难所。与之相反，落基山杜父鱼则栖息于多数布莱克富特河与克拉克福克河支流的下游暖水区段，以及两条河流的部分干流河段，但在比特鲁特河流域内无分布记录。该类群的存续大概率将直接或间接地受未来水温变化的影响，因此杜父鱼可作为研究与监测气候变化引发的生物群落变化的理想指示类群。