Since the Industrial Revolution, atmospheric CO2 levels have risen at an unprecedented rate. As atmospheric CO2 increase, ocean warming (OW) and ocean acidification (OA) are occurring at an unprecedented rate, posing a threat to marine organisms, especially in polar regions. Studies have already begun to show the impacts of temperature and CO2 on adult stages of polar fishes, but few studies have assessed vulnerable early life history stages. In this study, we exposed juvenile Trematomus bernacchii to projected OA (800 μatm pCO2 and 1250 μatm pCO2) and OW (+2ºC) scenarios and measured changes in cardiorespiration, including heart and ventilation rate over an acute (48 h to 7 days) and long-term (14 to 28 days) acclimation time.
Results/Conclusions
We found projected OA and OW significantly affect cardiorespiratory physiology in the juvenile T. bernacchii with implications of increased metabolic costs and oxygen demands. While increased temperature significantly increased heart rate, elevated pCO2 had no effect. An additive effect was apparent in ventilation rate as both temperature and pCO2 significantly increased ventilation rate. Projected OA and OW significantly affected cardiorespiratory physiology of the juvenile emerald rockcod, suggesting increased energetic costs associated with coping with future ocean conditions. OA and OW conditions will occur over the next decades and therefore longer term experiments are required to examine whether elevated costs of living may ultimately impact reproductive output and overall fitness of fishes.