Our project aims to understand how coccolithophore responses to ocean acidification (OA) change nanoplankton community structures. We hypothesize that coccolithophore responses to OA will negatively affect nanoplankton community structures. Through a combination of lab and field work, we will observe these phytoplankton in their natural environments. This study will advance our knowledge of how calcareous phytoplankton and plankton communities will behave in future acidic oceans.