Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington.
Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington.
Glob Chang Biol. 2019 Mar;25(3):963-977. doi: 10.1111/gcb.14532. Epub 2018 Dec 18.
Elevated concentrations of CO in seawater can disrupt numerous sensory systems in marine fish. This is of particular concern for Pacific salmon because they rely on olfaction during all aspects of their life including during their homing migrations from the ocean back to their natal streams. We investigated the effects of elevated seawater CO on coho salmon (Oncorhynchus kisutch) olfactory-mediated behavior, neural signaling, and gene expression within the peripheral and central olfactory system. Ocean-phase coho salmon were exposed to three levels of CO , ranging from those currently found in ambient marine water to projected future levels. Juvenile coho salmon exposed to elevated CO levels for 2 weeks no longer avoided a skin extract odor that elicited avoidance responses in coho salmon maintained in ambient CO seawater. Exposure to these elevated CO levels did not alter odor signaling in the olfactory epithelium, but did induce significant changes in signaling within the olfactory bulb. RNA-Seq analysis of olfactory tissues revealed extensive disruption in expression of genes involved in neuronal signaling within the olfactory bulb of salmon exposed to elevated CO , with lesser impacts on gene expression in the olfactory rosettes. The disruption in olfactory bulb gene pathways included genes associated with GABA signaling and maintenance of ion balance within bulbar neurons. Our results indicate that ocean-phase coho salmon exposed to elevated CO can experience significant behavioral impairments likely driven by alteration in higher-order neural signal processing within the olfactory bulb. Our study demonstrates that anadromous fish such as salmon may share a sensitivity to rising CO levels with obligate marine species suggesting a more wide-scale ecological impact of ocean acidification.
海水中 CO 浓度升高会破坏海洋鱼类的许多感觉系统。这对太平洋三文鱼尤其重要，因为它们在生命的各个阶段都依赖嗅觉，包括从海洋洄游回到出生地的溪流。我们研究了升高的海水 CO 对银大麻哈鱼（Oncorhynchus kisutch）嗅觉介导行为、外周和中枢嗅觉系统中的神经信号和基因表达的影响。海洋阶段的银大麻哈鱼暴露在三种 CO 浓度下，范围从环境海水中现有的 CO 浓度到预计的未来 CO 浓度。在升高的 CO 水平下暴露 2 周的幼年银大麻哈鱼不再回避一种皮肤提取物气味，而这种气味会引起在环境 CO 海水中维持的银大麻哈鱼的回避反应。暴露在这些升高的 CO 水平不会改变嗅觉上皮中的气味信号，但确实会引起嗅球内信号的显著变化。嗅觉组织的 RNA-Seq 分析显示，暴露于升高的 CO 中的三文鱼嗅球中与神经元信号传导有关的基因表达广泛中断，而对嗅球中的气味受体细胞的基因表达影响较小。嗅球基因途径的中断包括与 GABA 信号传导和嗅球神经元内离子平衡维持有关的基因。我们的结果表明，暴露于升高的 CO 中的海洋阶段银大麻哈鱼可能会经历显著的行为障碍，这可能是由嗅球内高级神经信号处理的改变驱动的。我们的研究表明，像三文鱼这样的溯河洄游鱼类可能与海洋物种一样对不断上升的 CO 水平敏感，这表明海洋酸化对更广泛的生态系统产生影响。
