Summary Since industrialization global CO 2 emissions have increased, and as a consequence oceanic pH is predicted to drop by 0.3–0.4 units before the end of the century – a process coined ‘ocean acidification’. Consequently, there is significant interest in how pH changes will affect the ocean's biota and integral processes. We investigated marine picoplankton (0.2–2 µm diameter) community response to predicted end of century...