The Impact of Elevated Carbon Dioxide (CO2) on Alarm Cue Behaviors in Fathead Minnows

The spread of invasive species poses a serious threat to aquatic ecosystems.  Previous research has shown that elevated CO₂ impairs fish movement, thus making it a potentially powerful tool to block further movement of invasive fishes.  However, at present, there are unknowns that need to be addressed prior to deploying CO₂ barriers, such as impacts to non-target taxa.  Recent work in the marine environment suggests that increased CO₂ levels due to climate change can negatively affect a fish’s ability to detect predators, home to natal environments, and perform aerobically; thus, elevated CO₂ may have equally negative impacts on freshwater communities, an area that remains understudied.  The objective of our study was to quantify the impacts of elevated CO₂ on Fathead Minnow (Pimephales promelas) alarm pheromone behaviors.  Fathead Minnow behaviors associated with their response to a conspecific alarm pheromone were significantly impaired following exposure to elevated CO₂ levels for at least 96 hours.  Behaviors to the alarm pheromone did not completely re-establish after 15 days of returning fish to ambient CO₂ levels.  Potential impacts to non-target fishes following CO₂ exposure in both short- and long-term are discussed further.