Award: OCE-1314336

Rising carbon dioxide concentrations in the atmosphere influence ocean chemistry causing a similar increase in ocean carbon dioxide concentration. This process is called ocean acidification. Photosynthetic microbes called phytoplankton in the sunlit surface ocean take up this carbon dioxide, and convert it to biomass just like land plants. This process consumes carbon dioxide and produces oxygen, fueling the marine food web. Phytoplankton, just like land plants, are very different from each other forming different functional groups. This project sought to understand how different functional groups of phytoplankton would respond to elevated carbon dioxide in the water at levels expected by year 2100 – both in the short term, and over the long-term, to give phytoplankton a chance to adapt to these new conditions. The primary goals of this project were to: 1) examine how increased carbon dioxide affects the major functional groups of marine phytoplankton; 2) evolve phytoplankton for many generations in elevated carbon dioxide; 3) compare how evolved phytoplankton respond to elevated carbon dioxide relative to their ancestors. Broader impacts were focused on increasing awareness of ocean acidification, and diversifying the STEM workforce. We learned that different functional groups of phytoplankton respond differently to increased carbon dioxide, in some cases changing growth rates, carbon capture and metabolism machinery, cellular composition and behavior to name a few. These responses were non-linear, meaning that the changes did not always decrease or increase consistently with increasing carbon dioxide. This provides important baseline information for ongoing efforts to model, or predict, the distribution of phytoplankton functional groups in the future ocean. This is critical because different phytoplankton communities support different food webs. Phytoplankton from many different functional groups were evolved for roughly 500 generations. These evolved phytoplankton are preserved in ultra-cold conditions and can be revived for further study. Thus, these phytoplankton represent a valuable resource for further study by the scientific community. In a comparison of evolved phytoplankton responses to elevated carbon dioxide, it appears that changes in growth rates can be predicted based on ancestor responses. If this pattern is found in future studies then it may offer a tool with which to model, or predict, the distribution of phytoplankton functional groups in the future ocean. The project participants raised awareness of ocean acidification through public talks and outreach events. We developed a hands-on learning activity about ocean acidification, exposing thousands of adults and children to information on the ocean, phytoplankton and carbon dioxide. In addition, two undergraduates who are underrepresented in STEM, were given advanced training through this project. Both of these women are now pursuing doctoral degrees in the aquatic sciences. Last Modified: 07/30/2019 Submitted by: Sonya Dyhrman