The Effects of Ocean Acidification on the Behavioral Responsiveness of Juvenile Walleye Pollock (Theragra chalcogramma) to Olfactory Cues

Ocean acidification is caused by anthropogenically released carbon dioxide dissolving into the oceans and decreasing the pH. Depressed pH and elevated CO₂ concentrations have been shown to reduce survival, growth rates, and disrupt behavioral sensitivity to olfactory cues for some marine species. However, little is known about the behavioral effects of ocean acidification on temperate and boreal marine fishes, such as walleye pollock (Theragra chalcogramma). Because juvenile walleye pollock inhabit physiochemically stable pelagic waters, they may be more sensitive to changes in their environment than fishes found in coastal zones which may have naturally higher CO₂ levels. This study will investigate the threshold level of prey scent required to elicit a behavioral response in juveniles (~50mm TL) and determine how decreased pH conditions alter behavioral response to olfactory cues. Fish will be reared and tested at three pH levels (ambient seawater, 7.6, or 7.4). Olfactory sensitivity in each pH treatment is evaluated by injecting increasing concentrations of prey scent cue into the flume until the fish exhibits a behavioral response to the cue (increased swimming activity). Changes in scent detection could reduce the ability to find food and avoid predators leading to increased mortality. This study will help understand the effects of ocean acidification on the behavioral sensitivity of juvenile walleye pollock to olfactory cues and determine if ocean acidification-induced disruption of olfactory ability is common in marine fishes.