Competitive fitness of a predominant pelagic calcifier impaired by ocean acidification

Coccolithophores form extensive blooms and increase the density and sinking speed of organic matter via calcium carbonate ballasting. Thereby, they play a key role in the marine carbon cycle.

Coccolithophore physiological responses to experimental ocean acidification have ranged from moderate stimulation to substantial decline in growth and calcification rates, combined with enhanced malformation of their calcite platelets. Here we report on a mesocosm experiment conducted in a Norwegian fjord in which we exposed a natural plankton community to a wide range of CO2-induced ocean acidification, to test whether these physiological responses affect the ecological success of coccolithophore populations.