Coccolithophores, single-celled calcifying phytoplankton that play a key role in the Earth’s climate system, might lose their competitive fitness in a future ocean. In a field experiment investigating the effects of ocean acidification on the coccolithophore Emiliania huxleyi in its natural environment, the species failed to form blooms. It is especially in these periods of exponential growth that the algae contribute massively to elemental cycling, including the transport of carbon to the deep ocean. Based on their observations, a team of researchers led by GEOMAR Helmholtz Centre for Ocean Research Kiel concludes, that a small physiological response to ocean acidification was amplified through ecological interactions large enough to cause a massive impact on the ecosystem. The results of the study are published in the journal Nature Geoscience.