Fishes in high-CO2, acidified oceans

Research interest in CO2-driven ocean acidification has been centered on certain groups of calcifying marine organisms, but knowledge on the possible impacts of ocean acidification on fish is limited. Our survey of the existing literature on the effects of increased pCO(2) on fish (total of 116 papers) revealed that few studies were conducted under pCO(2) conditions relevant to the future scenarios of ocean acidification. Information is nearly absent on reproduction, early development, and behaviour of marine fish. The short experimental durations of these studies preclude forecasting of how mortality and growth of marine fish would be affected by future increases in seawater CO2, Fish have been shown to maintain their oxygen consumption under elevated pCO(2) conditions, in contrast to declines seen in several marine invertebrates, in spite of possible additional energetic costs incurred by higher pCO(2). Impacts of prolonged CO2 exposure on reproduction, early development, growth, and behaviour of marine fish are important areas that need urgent investigation. There is also a need to rapidly advance research into possible acclimation of marine fish to high pCO(2) environments, endocrine responses to prolonged CO2 exposure, and indirect influences through food availability and quality on fish growth, survival and reproduction. Useful guidance could be gained from the rich literature on the effects of freshwater acidification.