Data from: Climate, invasive species and land use drive population dynamics of a cold-water specialist

1. Climate change is an additional stressor in a complex suite of threats facing freshwater biodiversity, particularly for cold-water fishes. Research addressing the consequences of climate change on cold-water fish has generally focused on temperature limits defining spatial distributions, largely ignoring how climatic variation influences population dynamics in the context of other existing stressors. 2. We used long-term data from 92 populations of bull trout (Salvelinus confluentus) – one of North America’s most cold-adapted fishes – to quantify additive and interactive effects of climate, invasive species, and land-use on population dynamics (abundance, variability, and growth rate). 3. Populations were generally depressed, more variable, and declining where spawning and rearing stream habitat was limited, invasive species and land-use were prevalent, and stream temperatures were highest. Increasing stream temperature acted additively and independently, whereas land-use and invasive species had additive and interactive effects (i.e., the impact of one stressor depended on exposure to the other stressor). 4. Most (58-78%) of the explained variation in population dynamics was attributed to the presence of invasive species, differences in life history, and management actions in foraging habitats in rivers, lakes, and reservoirs. Although invasive fishes had strong negative effects on populations in foraging habitats, proactive control programs appeared to effectively temper their negative impact. 5. Synthesis and applications: Long-term demographic data emphasize that climate warming will exacerbate imperilment of cold water specialists like bull trout, yet other human stressors – especially invasive fishes – are immediate threats that can be addressed by proactive management actions. Thus, climate adaptation strategies for freshwater biodiversity should consider existing abiotic and biotic stressors, some of which provide potential and realized opportunity for conservation of freshwater biodiversity in a warming world.29-Jul-20161. 气候变化是淡水生物多样性所面临的多重复杂威胁中的额外胁迫因子，对冷水性鱼类而言尤为如此。现有针对气候变化对冷水性鱼类影响的研究，大多聚焦于温度阈值对物种空间分布的限定作用，却很大程度上忽略了在其他现存胁迫因子的背景下，气候变异如何影响种群动态。 2. 本研究使用了北美适应性最强的冷水性鱼类之一——公牛红点鲑（Salvelinus confluentus）的92个种群的长期监测数据，以量化气候、入侵物种及土地利用对种群动态（包括丰度、波动幅度及生长速率）的加性效应与交互效应。 3. 当溪流产卵与育幼生境受限、入侵物种及土地利用胁迫普遍存在且溪流水温最高时，种群通常会出现丰度下降、波动加剧且持续衰退的情况。溪流水温升高呈现出独立的加性效应，而土地利用与入侵物种则同时存在加性效应与交互效应（即其中一种胁迫因子的影响程度取决于另一种胁迫因子的暴露水平）。 4. 种群动态中可解释的变异中，绝大多数（58%~78%）可归因于入侵物种的存在、生活史特征差异，以及河流、湖泊与水库觅食生境中的管理措施。尽管入侵鱼类对觅食生境中的种群产生了强烈的负面影响，但主动防控计划似乎能够有效缓解其负面影响。 5. 综合与应用：长期种群统计数据表明，气候变暖将加剧公牛红点鲑这类冷水专性物种的濒危程度，而其他人为胁迫因子——尤其是入侵鱼类——则是可通过主动管理措施加以应对的即时威胁。因此，淡水生物多样性的气候适应策略应考量现存的非生物与生物胁迫因子，其中部分因子可为变暖世界中的淡水生物多样性保护提供潜在且已被证实的可行路径。2016年7月29日