Asian carp are non-native invasive fishes that have quickly become the most abundant fishes in many portions of the Midwestern United States.While Asian carp are currently contained within the Mississippi River basin by a pair of electrified barriers, these fish have the potential to negatively impact the Great Lakes ecosystem if this barrier is breached.As such, novel barrier technologies would provide an additional mechanism to prevent Asian carp from invading the Great Lakes, and provide redundancy and safety to the current electric barrier.Therefore, the overall goal of this thesis was to quantify the impact of hypercarbia on the physiology, behavior, and performance of juvenile fish, with an emphasis on determining the effectiveness of carbon dioxide as a chemical deterrent of juvenile Asian carp movement.The first study used a combination of molecular and behavioral experiments to determine the effectiveness of carbon dioxide as a chemical deterrent for larval and juvenile fishes.Results from this study indicated that larval and juvenile fishes induced stress-related gene transcripts following an acute exposure to hypercarbia, and juvenile fishes will actively avoid elevated CO2 waters that are greater than 200 mg/L, indicating that a CO2 chemical barrier has potential to deter the movement of larval and juvenile Asian carp.The second study held largemouth bass at ambient CO2 (13 mg/L) and elevated CO2 (31 mg/L) for 58 days, and then used a combination of physiological, behavioral, and performance experiments to determine the acclimation capacity of fishes to chronic hypercarbia.Results from this study clearly indicated 1) acclimation to chronic hypercarbia causes plastic alterations in molecular and physiological parameters, 2) CO2-acclimated fish displayed a reduced stress response to an acute hypercarbia exposure compared to naïve fishes, 3) CO2-acclimated fish were less impacted by additional hypercarbia stressors, as shown by increased tolerance of CO2 in behavioral and swimming performance tests.This study suggested that largemouth bass exposed to chronic hypercarbia may possess a beneficial advantage over naïve fishes, due to increased oxygen uptake capacity and acid-base regulation, during periods of elevated carbon dioxide.Together, these two studies provide insight into the potential efficacy of a CO2 chemical deterrent for Asian carp by examining two potential caveats that could decrease the usefulness of the barrier.Additionally, results of this study can provide important information on the molecular, physiological, behavioral, and performance impacts of hypercarbia on freshwater fishes.
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Impact of hypercarbia on juvenile fish physiology, behavior, performance, and acclimation potential