Pacific Biological Station, Fisheries and Oceans Canada, 3190 Hammond Bay Rd, Nanaimo, BC V9T 6N7, Canada; Department of Fisheries, Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran.
Pacific Biological Station, Fisheries and Oceans Canada, 3190 Hammond Bay Rd, Nanaimo, BC V9T 6N7, Canada.
Sci Total Environ. 2024 Nov 15;951:175626. doi: 10.1016/j.scitotenv.2024.175626. Epub 2024 Aug 20.
Aquatic species are increasingly confronted with environmental stressors because of climate change. Although molecular technologies have advanced our understanding of how organisms respond to stressors in laboratory settings, the ability to detect physiological responses to specific stressors under complex field conditions remains underdeveloped. This research applied multi-stressor challenge trials on coho salmon, employing the "Salmon Fit-Chips" genomic tool and a random forest-based classification model to develop classifiers predictive for chronic thermal and hypoxic stress, as well as salinity acclimation, smolt stage and morbidity status. The study also examined how smolts and de-smolts (smolts not having entered SW during the smolt window) responded transcriptionally to exposure to saltwater. Using RF classifiers optimized with 4 to 12 biomarkers, we identified transcriptional signatures that accurately predicted the presence of each stressor and physiological state, achieving prediction accuracy rates between 86.8 % and 100 %, regardless of other background stressors present. Stressor recovery time was established by placing fish back into non-stressor conditions after stress exposure, providing important context to stressor detections in field applications. Recovery from thermal and hypoxic stress requires about 3 and 2 days, respectively, with >3 days needed for re-acclimation to freshwater for seawater acclimated fish. The study also found non-additive (synergistic) effects of multiple stressors on mortality risk. Importantly, osmotic stress associated with de-smolts was the most important predictor of mortality. In saltwater, de-smolts exposed to salinity, high temperature, and hypoxia experienced a 9-fold increase in mortality compared to those only exposed to saltwater, suggesting a synergistic response to multiple stressors. These findings suggest that delays in hatchery releases to support release of larger fish need to be carefully scrutinized to ensure fish are not being released as de-smolts, which are highly susceptible to additional climate-induced stressors like rising temperatures and reduced dissolved oxygen levels in the marine environment.
由于气候变化，水生生物越来越多地面临环境胁迫。尽管分子技术已经提高了我们对生物在实验室环境中对胁迫因子的反应的理解，但在复杂的野外条件下检测特定胁迫因子的生理反应的能力仍未得到充分发展。本研究对银大麻哈鱼进行了多胁迫挑战试验，应用“鲑鱼适应芯片”基因组工具和基于随机森林的分类模型，开发了用于预测慢性热胁迫和缺氧胁迫以及盐度驯化、幼鱼期和发病状态的分类器。该研究还研究了幼鱼和去幼鱼（在幼鱼期窗口期间未进入 SW 的幼鱼）在暴露于海水中时转录反应如何。使用优化了 4 到 12 个生物标志物的 RF 分类器，我们确定了准确预测每个胁迫因子和生理状态存在的转录特征，无论存在其他背景胁迫因子，预测准确率在 86.8%到 100%之间。通过在应激暴露后将鱼类放回非应激条件下，确定了应激恢复时间，这为野外应用中的应激检测提供了重要背景。热应激和缺氧应激的恢复分别需要大约 3 天和 2 天，而海水驯化的鱼类重新适应淡水则需要 3 天以上。该研究还发现多种胁迫因子对死亡率风险的非加性（协同）效应。重要的是，与去幼鱼相关的渗透胁迫是死亡率的最重要预测因子。在海水中，与盐度、高温和缺氧一起暴露的去幼鱼的死亡率比仅暴露于盐水中的去幼鱼增加了 9 倍，这表明对多种胁迫因子存在协同反应。这些发现表明，在确保鱼类不会作为幼鱼释放时，需要仔细审查延迟孵化场释放以支持更大鱼类的释放，因为幼鱼极易受到额外的气候诱导胁迫因子的影响，例如海水环境中温度升高和溶解氧水平降低。
