Frommel Andrea Y, Akbarzadeh Arash, Chalifoux Virginie, Ming Tobi J, Collicutt Brenna, Rolheiser Kate, Opie Rumer, Miller Kristina M, Brauner Colin J, Hunt Brian P V
Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada.
Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada.
Ecol Appl. 2025 Jul;35(5):e70058. doi: 10.1002/eap.70058.
Salmon populations are declining worldwide, with high mortality rates during juvenile marine migration presenting a bottleneck to recruitment. The ocean conditions along the main migratory route of juvenile salmon in British Columbia are characterized by high variability in CO, with the amplitude, duration, and frequency of ocean acidification events exacerbated by climate change. Similarly, the variability in ocean conditions affects the abundance and diversity of plankton prey, leading to areas of food paucity for juvenile salmon. We investigated the combined effects of ocean acidification (control and 3200 μatm CO) and food limitation (ad libitum, ½ ration, and food deprived) on the survival, condition, and gene expression profiles of juvenile Chum salmon (Oncorhynchus keta) to develop predictive biomarkers for CO exposure and food deprivation. Ocean acidification caused a direct 3-fold increase in mortality over 25 days of exposure, which was unaffected by food availability but differentially affected smaller fish. CO exposure induced transcriptomic changes in a suite of genes associated with ion regulation, while food deprivation was associated with a differential expression of stress, immune, and mortality markers, as well as reduced condition factor. Our data indicate that CO directly impairs ionoregulatory capacity to the point of failure in juvenile Chum salmon and that these effects cannot be compensated through increased energy from food. Applying our gene panels as biomarkers to a subset of fish with known exposure, we were able to accurately predict exposure to CO and food deprivation (74% and 90%, respectively). By combining these gene panels with previously established biomarkers for other environmental stressors, the recent environmental stress history of wild fish can be determined and can be used in models to predict salmon returns, informing fisheries management and conservation efforts.
全球范围内鲑鱼数量正在减少，幼鱼在海洋洄游期间的高死亡率成为补充种群数量的瓶颈。不列颠哥伦比亚省幼鲑主要洄游路线沿线的海洋状况特点是二氧化碳含量高度可变，气候变化加剧了海洋酸化事件的幅度、持续时间和频率。同样，海洋状况的变化会影响浮游生物猎物的丰度和多样性，导致幼鲑出现食物匮乏的区域。我们研究了海洋酸化（对照和3200微大气压二氧化碳）和食物限制（自由摄食、半量投喂和饥饿）对银大麻哈鱼（Oncorhynchus keta）幼鱼的存活、状况和基因表达谱的综合影响，以开发用于预测二氧化碳暴露和食物剥夺的生物标志物。在25天的暴露期间，海洋酸化使死亡率直接增加了3倍，这不受食物供应情况的影响，但对较小的鱼有不同程度的影响。二氧化碳暴露诱导了一系列与离子调节相关基因的转录组变化，而食物剥夺与应激、免疫和死亡率标志物的差异表达以及状况因子降低有关。我们的数据表明，二氧化碳直接损害了银大麻哈鱼幼鱼的离子调节能力，直至衰竭，而且这些影响无法通过增加食物能量来补偿。将我们的基因组合作为生物标志物应用于已知暴露情况的一部分鱼类，我们能够准确预测二氧化碳暴露和食物剥夺（分别为74%和90%）。通过将这些基因组合与先前建立的针对其他环境应激源的生物标志物相结合，可以确定野生鱼类近期的环境应激历史，并可将其用于模型中预测鲑鱼的洄游情况，为渔业管理和保护工作提供信息。
