Lindley Elizabeth D, Dunmall Karen M, Westley Peter A H
College of Fisheries and Ocean Sciences University of Alaska Fairbanks Fairbanks Alaska USA.
Freshwater Institute Fisheries and Oceans Canada Winnipeg Manitoba Canada.
Ecol Evol. 2025 Jan 11;15(1):e70797. doi: 10.1002/ece3.70797. eCollection 2025 Jan.
Warming associated with climate change is driving poleward shifts in the marine habitat of anadromous Pacific salmon ( spp.). Yet the spawning locations for salmon to establish self-sustaining populations and the consequences for the ecosystem if they should do so are unclear. Here, we explore the role of temperature-dependent incubation survival and developmental phenology of coho salmon () as a potential early life history barrier to establishment in an Arctic stream. We exposed embryos to temperatures previously recorded in the substrate of an Arctic groundwater spring-fed spawning environment. Using a common garden experimental design, coho salmon embryos were exposed to treatments that thermally mimicked four spawning dates from August 1 to October 1 (AUG1, SEPT1, SEPT15, and OCT1). Spawning temperatures were 6°C at the warmest (AUG1) and 1.25°C at the coldest (OCT1). We observed low survival rates in SEPT1 (41%) and OCT1 (34%) and near complete mortality in the other treatments. While far below what is considered normal in benign hatchery-like conditions, these rates suggest that temperatures experienced at these spawning dates are survivable. We detected differences in developmental rates across treatments; embryos developed 1.9 times faster in the warmest treatment (AUG1, 120 days) compared to the coldest (OCT1, 231 days). Differences in accumulated thermal units (ATUs) needed for hatching ranged from 392 ATUs in AUG1 to 270 ATUs in OCT1, revealing compensation in developmental requirements. Given these findings, the most thermally suitable spawning dates within our study are between September 15 and October 1, which facilitates hatching and projected nest emergence to occur in spring warming conditions (March-September). Broadly, our findings suggest that spawning sites within thermal tolerances that can support the survival and development of coho salmon exist in the North American Arctic. Whether the habitat is otherwise suitable for transitions through other life stages remains unknown.
与气候变化相关的变暖正在推动溯河洄游的太平洋鲑鱼（多种）的海洋栖息地向极地转移。然而，鲑鱼建立自我维持种群的产卵地点以及如果它们这样做对生态系统的影响尚不清楚。在这里，我们探讨了银大麻哈鱼（）依赖温度的孵化存活率和发育物候作为在北极溪流中建立种群的潜在早期生活史障碍的作用。我们将胚胎暴露于北极地下水泉补给的产卵环境基质中先前记录的温度下。采用共同花园实验设计，将银大麻哈鱼胚胎暴露于热模拟8月1日至10月1日四个产卵日期的处理中（8月1日、9月1日、9月15日和10月1日）。最温暖时（8月1日）的产卵温度为(6^{\circ}C)，最冷时（10月1日）为(1.25^{\circ}C)。我们观察到9月1日（41%）和10月1日（34%）的存活率较低，而其他处理几乎全部死亡。虽然远低于在类似良性孵化场条件下被认为正常的水平，但这些比率表明在这些产卵日期经历的温度是可以存活的。我们检测到各处理之间发育速率的差异；与最冷处理（10月1日，231天）相比，最温暖处理（8月1日，120天）中的胚胎发育速度快1.9倍。孵化所需的累积热单位（ATUs）差异范围从8月1日的392 ATUs到10月1日的270 ATUs，揭示了发育需求的补偿。鉴于这些发现，我们研究中最适合热条件的产卵日期在9月15日至10月1日之间，这有利于在春季变暖条件下（3月至9月）孵化和预计的巢穴出现。总体而言，我们的研究结果表明，北美北极地区存在温度耐受范围内能够支持银大麻哈鱼生存和发育的产卵地点。该栖息地是否在其他方面适合鲑鱼度过其他生命阶段仍不清楚。
