CO2-Induced Aquatic Acidification Impairs Early Growth, Metabolism, Olfaction and Behavior in Juvenile Pink Salmon (Oncorhynchus gorbuscha)

Ocean acidification has been shown to negatively affect many marine species and is predicted to cause widespread changes to marine ecosystems. Similarly, freshwater ecosystems may potentially be affected by climate change-related acidification; however, this has received far less attention. Freshwater fish represent 40% of all fishes and salmon, which rear and spawn in freshwater, are of immense ecosystem, economical and cultural importance. In this study, we investigate the impacts of CO₂-induced acidification during early life stages in pink salmon, the most abundant species of Pacific salmon, throughout freshwater development and following seawater entry. Here, we show that projected future CO₂ levels result in a substantial reduction in growth, yolk to tissue conversion efficiency, and maximal metabolic rate and result in significant alterations in olfactory responses, anti-predator behavior and anxiety at a critical and sensitive life-stage; the time they would be leaving freshwater and entering seawater for their extended marine migration.