Streamflow and temperature regimes are key components of the physical habitats of instream biological communities. Iberian brown trout (Salmo trutta) populations exist in a climatic border where water scarcity and increasing water temperatures during summer could compromise their viability throughout the 21st century. We predicted climate change‐induced modifications in the thermal and hydraulic habitats of both the intragravel (eggs and larvae) and free‐swimming (fry, juveniles and adults) stages of brown trout in two mountain streams in central Spain. Spatial–temporal simulations of thermal and hydraulic habitats under two climate change emission scenarios—representative concentration pathway (RCP) 4.5 (mild scenario) and RCP 8.5 (pessimistic)—were conducted at 1‐m altitudinal steps using daily air temperature and streamflow predictions. Increased winter temperatures will reduce embryo and larval development time by 12% (RCP 4.5) and 30% (RCP 8.5) in downstream sites by end of the 21st century, but this reduction might be insufficient to compensate for the shortening of the period with temperatures below the viability limits for survival of intragravel phase (20% and 54%, respectively). Combining streamflow and temperature data for free‐swimming stages indicated that the suitable summer habitat will be reduced by between 53% and 76% (RCP 4.5) and 70%–90% (RCP 8.5) by 2099. The predicted effects for all developmental stages are critical for determining population viability at both ends of its altitudinal distribution. However, these responses are river‐specific, as limiting factors differ among rivers.

中文翻译：

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气候变化对其居住分布区后缘的溪流褐鳟（Salmo trutta Linnaeus，1758）的生活阶段的影响

径流和温度状态是河流生物群落物理生境的关键组成部分。伊比利亚褐鳟（Salmo trutta）人口存在于气候边界，夏季缺水和水温升高可能会损害整个21世纪的生存能力。我们预测了西班牙中部两个山区溪流中鳟鱼的卵内（卵和幼虫）阶段和自由游泳（油炸，少年和成年）阶段的热力和水力生境的气候变化诱发的变化。使用每日空气温度和流量预测，在海拔高度为1米的情况下，对两种气候变化排放情景（代表性浓度路径（RCP）4.5（轻度情景）和RCP 8.5（悲观））下的热力和水力栖息地进行了时空模拟。冬季温度的升高将使胚胎和幼虫的发育时间减少12％（RCP 4.5）和30％（RCP 8）。5）到21世纪末在下游站点，但是这种降低可能不足以弥补温度低于砾石内相生存能力极限（分别为20％和54％）的时期的缩短。自由泳阶段的流量和温度数据相结合表明，到2099年，合适的夏季栖息地将减少53％至76％（RCP 4.5）和70％–90％（RCP 8.5）。所有发育阶段的预测影响对于确定种群高度分布两端的生存能力至关重要。但是，这些响应是特定于河流的，因为限制因素在河流之间有所不同。分别）。自由泳阶段的流量和温度数据相结合表明，到2099年，合适的夏季栖息地将减少53％至76％（RCP 4.5）和70％–90％（RCP 8.5）。所有发育阶段的预测影响对于确定种群高度分布两端的生存能力至关重要。但是，这些响应是特定于河流的，因为限制因素在河流之间有所不同。分别）。自由泳阶段的流量和温度数据相结合表明，到2099年，合适的夏季栖息地将减少53％至76％（RCP 4.5）和70％–90％（RCP 8.5）。所有发育阶段的预测影响对于确定种群高度分布两端的生存能力至关重要。但是，这些响应是特定于河流的，因为限制因素在河流之间有所不同。