Coyle Oliver, Vredenburg Vance T, Stillman Jonathon H
Department of Biology San Francisco State University San Francisco California USA.
Museum of Vertebrate Zoology University of California Berkeley Berkeley California USA.
Ecol Evol. 2024 May 6;14(5):e11371. doi: 10.1002/ece3.11371. eCollection 2024 May.
Organisms within freshwater and marine environments are subject to a diverse range of often co-occurring abiotic and biotic stressors. Despite growing awareness of the complex multistress systems at play in aquatic ecosystems, many questions remain regarding how simultaneous stressors interact with one another and jointly impact aquatic species. We looked at multistress interactions in a protected stream ecosystem in Mendocino County, California. Specifically, we examined how diurnal temperature variation, turbidity, and predator cues altered the movement speed of larval Pacific giant salamanders (). In a second experiment, we looked at how simulated low-flow summer conditions impact the expression of heat-shock proteins (HSPs) in the same species. Larvae moved almost one and a half times faster in the presence of chemical cues from trout and suspended sediment, and almost two times faster when both sediment and trout cues were present but were only marginally affected by temperature and visual cues from conspecifics. Interestingly, the order of stressor exposure also appeared to influence larval speed, where exposure to sediment and trout in earlier trials tended to lead to faster speeds in later trials. Additionally, larvae exposed to low-flow conditions had more variable, but not statistically significantly higher, expression of HSPs. Our findings highlight the potential interactive effects of an abiotic stressor, sedimentation, and a biotic stressor, and predator chemical cues on an ecologically important trait: movement speed. Our findings also demonstrate the likely role of HSPs in larval salamander survival in challenging summer conditions. Taken together, these findings show that larval responds behaviorally to biotic and abiotic stressors and suggests a possible pathway for physiological tolerance of environmental stress. Consideration of multistress systems and their effects is important for understanding the full effects of co-occurring stressors on aquatic organisms to guide appropriate conservation and management efforts based on ecologically relevant responses of organisms within an environment.
淡水和海洋环境中的生物会受到各种各样经常同时出现的非生物和生物应激源的影响。尽管人们越来越意识到水生生态系统中复杂的多重应激系统在起作用，但关于同时存在的应激源如何相互作用并共同影响水生物种，仍有许多问题。我们研究了加利福尼亚州门多西诺县一个受保护的溪流生态系统中的多重应激相互作用。具体来说，我们研究了昼夜温度变化、浊度和捕食者线索如何改变太平洋巨型蝾螈幼体的移动速度。在第二个实验中，我们研究了模拟的夏季低流量条件如何影响同一物种中热休克蛋白（HSPs）的表达。在有鳟鱼的化学线索和悬浮沉积物的情况下，幼体的移动速度几乎快了一倍半，当沉积物和鳟鱼线索都存在时，移动速度几乎快了两倍，但仅受到温度和同种个体视觉线索的轻微影响。有趣的是，应激源暴露的顺序似乎也会影响幼体的速度，在早期试验中接触沉积物和鳟鱼的幼体在后期试验中往往移动速度更快。此外，暴露于低流量条件下的幼体热休克蛋白的表达更具变异性，但在统计学上没有显著升高。我们的研究结果突出了非生物应激源（沉积）和生物应激源（捕食者化学线索）对一个生态重要特征——移动速度的潜在交互作用。我们的研究结果还证明了热休克蛋白在蝾螈幼体在具有挑战性的夏季条件下生存中的可能作用。综上所述，这些研究结果表明蝾螈幼体对生物和非生物应激源有行为反应，并暗示了一条环境应激生理耐受性的可能途径。考虑多重应激系统及其影响对于理解同时存在的应激源对水生生物的全面影响至关重要，以便根据环境中生物的生态相关反应来指导适当的保护和管理工作。
