Much research has focused on the population-level effects of climate change on Eastern Brook Trout (Salvelinus fontinalis). While some studies have considered here sub-lethal stress caused by warming waters, the role of multiple, interacting stressors remains largely unexplored. We used inducible heat shock protein 70 (HSP70) as a molecular biomarker to assess in situ response of Eastern Brook Trout in headwater streams to multiple potential stressors, including temperature. Over 7 sampling events during 2018 and 2019, we sampled 141 fish and found that HSP70 expression and 3-day mean water temperature exhibited a quadratic relationship (R2-adj = 0.68). Further analyses showed that HSP70 expression was explained by temperature, relative water level and their interaction (R2-adj = 0.75), while fish size and capture location were not factors. We observed a significant increase in HSP70 expression during periods of low relative water level with warm temperatures (~18°C) and also during high relative water level with cold temperatures (~8°C). Our results suggest that temperatures at the edges of the preferred range coupled with relative water level might act together to trigger the cellular stress response in Eastern Brook Trout and that there is greater variation in response at colder temperatures. These findings reinforce the need to consider complex, interactive stressors in influencing the health and persistence of Eastern Brook Trout populations into the future.

中文翻译：

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东溪鳟鱼诱导型 HSP70 表达的环境背景

许多研究都集中在气候变化对东溪鳟鱼（Salvelinus fontinalis）的种群水平影响上。虽然一些研究在这里考虑了由海水变暖引起的亚致死压力，但多种相互作用的压力源的作用在很大程度上仍未得到探索。我们使用诱导型热休克蛋白 70 (HSP70) 作为分子生物标志物来评估东溪鳟鱼在源头流中对多种潜在压力源（包括温度）的原位反应。在 2018 年和 2019 年的 7 次采样事件中，我们对 141 条鱼进行了采样，发现 HSP70 表达与 3 天平均水温呈二次关系（R2-adj = 0.68）。进一步的分析表明，温度、相对水位及其相互作用（R2-adj = 0.75）可以​​解释 HSP70 的表达，而鱼的大小和捕获位置不是因素。我们观察到 HSP70 表达在相对水位较低且温度较高 (~18°C) 期间以及在相对水位较高且温度较低 (~8°C) 期间显着增加。我们的研究结果表明，优选范围边缘的温度与相对水位相结合可能共同触发东溪鳟鱼的细胞应激反应，并且在较冷的温度下反应有更大的变化。这些发现强调了在影响东溪鳟鱼种群未来的健康和持久性方面考虑复杂的互动压力源的必要性。我们的研究结果表明，优选范围边缘的温度与相对水位相结合可能共同触发东溪鳟鱼的细胞应激反应，并且在较冷的温度下反应有更大的变化。这些发现强调了在影响东溪鳟鱼种群未来的健康和持久性方面考虑复杂的互动压力源的必要性。我们的研究结果表明，优选范围边缘的温度与相对水位相结合可能共同触发东溪鳟鱼的细胞应激反应，并且在较冷的温度下反应有更大的变化。这些发现强调了在影响东溪鳟鱼种群未来的健康和持久性方面考虑复杂的互动压力源的必要性。