Influence of Nutritional Status on Carbon Dioxide Tolerance and Avoidance Behavior in a Freshwater Teleost

Abstract

AbstractChallenging environmental conditions can induce voluntary behavioral avoidance in animals. Dissolved carbon dioxide (CO2) is an environmental stressor that was previously shown to upregulate the stress axis in fish and also causes voluntary avoidance. Variation in individual state or context, such as whether an animal is fasted or fed, can alter animal behavior, including the response to environmental challenges. In the current study, we sought to define the influence of nutritional status on the response of Largemouth Bass Micropterus salmoides to elevated CO2. Two groups of Largemouth Bass—one fed group and one fasted group—were first subjected to a CO2 shuttling protocol to define avoidance thresholds, followed by a CO2 tolerance protocol to define the time required to lose equilibrium and recover. Data showed that although feeding and fasting had no influence on the avoidance of CO2, fasted fish required 17% longer to lose equilibrium in elevated CO2. Avoidance of elevated CO2 is therefore independent of animal state, but fish in poor nutritional condition from fasting are more tolerant. Thus, managers considering elevated CO2 as a nonphysical barrier to deter fish movements should be cognizant of food availability, as fasted animals may require increased partial pressures of CO2 to ensure successful deterrence.