Elevated CO₂ impairs olfactory‐mediated neural and behavioral responses and gene expression in ocean‐phase coho salmon (Oncorhynchus kisutch)

Abstract

Elevated concentrations of CO2 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 CO2 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 CO2, ranging from those currently found in ambient marine water to projected future levels. Juvenile coho salmon exposed to elevated CO2 levels for 2 weeks no longer avoided a skin extract odor that elicited avoidance responses in coho salmon maintained in ambient CO2 seawater. Exposure to these elevated CO2 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 CO2, 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 CO2 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 CO2 levels with obligate marine species suggesting a more wide‐scale ecological impact of ocean acidification.

Impacts of Global Warming and Elevated CO2 on Sensory Behavior in Predator-Prey Interactions: A Review and Synthesis

“…Future atmospheric conditions have also been shown to mask carbon dioxide cues used by mosquitos to find their hosts (Majeed et al, 2014), with elevated CO 2 background levels causing a reduction in olfactory receptor sensitivity and potentially habituation in higher-order neurons (i.e., cue processing). Disruptions of processing in the olfactory bulb receptor pathway also has been demonstrated in oceanphase coho salmon that show reduced avoidance of chemical alarm cues as a result of elevated CO 2 (Williams et al, 2018).…”

Electrolytes for Dual‐Carbon Batteries

“…The excessive reliance on finite fossil fuels (coal, petroleum, natural gas) is a non‐sustainable practice that causes irreversible damage to the environment ,. Developing alternative energy sources such as wind, solar, waves, and tidal energy, has minimized fossil fuel consumption and reduced greenhouse gas emissions.…”

“…The excessive reliance on finite fossil fuels (coal, petroleum, natural gas) is a non-sustainable practice that causes irreversible damage to the environment. [1,2] Developing alternative energy sources such as wind, solar, waves, and tidal energy, has minimized fossil fuel consumption and reduced greenhouse gas emissions. To efficiently utilize these intermittent renewable resources, researchers have developed new energy storage technologies, among which the lithium-ion battery (LIB) is the dominant type used in modern consumer electronics and electric vehicles (EVs).…”

Ocean Acidification Amplifies the Olfactory Response to 2-Phenylethylamine: Altered Cue Reception as a Mechanistic Pathway?

“…We then investigate the relevance of different possible pathways by which pH can interfere with the observed behaviour. Mechanistically, info-disruption associated with ocean acidification has been linked to GABA receptor functioning in fish: the internal compensation for elevated CO 2 conditions leads to altered brain ion gradients, interfering with neurotransmitter function (Nilsson et al 2012; Williams et al 2019). Electrophysiological and transciptomic measurements also revealed an impaired olfactory system in elevated CO 2 conditions (Porteus et al 2018).…”