Studies predicting how the distribution of aquatic organisms will shift with climate change often use projected increases in air temperature or water temperature. However, the assumed correlations between water temperature change and air temperature change can be problematic, especially for mountainous, high elevation streams. Using stream fish assemblage data from 1,442 surveys across a mountain–plains gradient (Wyoming, USA; 1990–2018), we compared the responsiveness of thermal guilds, native status groups, and assemblage structure to projected climate warming from generalized air temperature models and stream-specific water temperature models. Air temperature models consistently predicted greater range shift differences between warm-water and cold-water species, with air temperatures predicting greater increases in occurrence and greater range expansions for warm-water species. The “over-prediction” of warm-water species expansions resulted in air temperature models predicting higher rates of novel species combinations, greater increases in local species richness, and higher magnitudes of biotic homogenization compared with water temperature models. Despite differences in model predictions for warm-water species, both air and water temperature models predicted that three cold-water species would exhibit similar decreases in occurrence (decline of 1.0% and 1.8% of sites per 1°C warming, respectively) and similar range contractions (16.6 and 21.5 m elevation loss per 1°C warming, respectively). The “over-prediction” for warm-water species is partially attributable to water temperatures warming at slower rates than air temperatures because local, stream-scale factors (e.g., riparian cover, groundwater inputs) buffer high elevation streams from rising air temperatures. Our study provides the first comparison of how inferences about climate-induced biotic change at the species- and assemblage-levels differ when modeling with generalized air temperatures versus stream-specific water temperatures. We recommend that future studies use stream-specific water temperature models, especially for mountainous, high elevation streams, to avoid the “over-prediction” of biotic changes observed from air temperature variables.

中文翻译：

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与水温相比，气温高估了随着气候变暖导致河流鱼类群落的变化

预测水生生物的分布将如何随着气候变化而变化的研究通常使用预计的气温或水温升高。然而，水温变化和气温变化之间假设的相关性可能存在问题，特别是对于山区、高海拔溪流。我们使用来自跨越山地平原梯度的 1,442 次调查的溪流鱼类组合数据（怀俄明州，美国；1990-2018 年），我们比较了热公会、本地状态组和组合结构对广义气温模型和溪流预测的气候变暖的响应能力- 特定的水温模型。气温模型一致预测温水和冷水物种之间更大的范围变化差异，气温预测温水物种的发生率和范围扩大幅度更大。与水温模型相比，温水物种扩张的“过度预测”导致气温模型预测新物种组合的比率更高，当地物种丰富度增加更多，生物同质化程度更高。尽管模型对温水物种的预测存在差异，但空气和水温模型都预测，三种冷水物种的发生率将呈现相似的下降（每升高 1°C 的地点分别下降 1.0% 和 1.8%）和相似的范围收缩（每升高 1°C，海拔分别降低 16.6 米和 21.5 米）。对温水物种的“过度预测”部分归因于水温变暖的速度比气温慢，因为当地的河流规模因素（例如河岸覆盖、地下水输入）缓冲了气温上升导致的高海拔河流。我们的研究首次比较了在使用广义气温与特定河流水温进行建模时，关于气候引起的物种和组合水平的生物变化的推断有何不同。我们建议未来的研究使用特定于河流的水温模型，特别是对于山区、高海拔的河流，以避免从气温变量中观察到的生物变化的“过度预测”。地下水输入）缓冲来自气温上升的高海拔溪流。我们的研究首次比较了在使用广义气温与特定河流水温进行建模时，关于气候引起的物种和组合水平的生物变化的推断有何不同。我们建议未来的研究使用特定于河流的水温模型，特别是对于山区、高海拔河流，以避免从气温变量中观察到的生物变化的“过度预测”。地下水输入）缓冲来自气温上升的高海拔溪流。我们的研究首次比较了在使用广义气温与特定河流水温进行建模时，关于气候引起的物种和组合水平的生物变化的推断有何不同。我们建议未来的研究使用特定于河流的水温模型，特别是对于山区、高海拔的河流，以避免从气温变量中观察到的生物变化的“过度预测”。