Photosynthetic marine microorganisms, or phytoplankton, use carbon dioxide to build their biomass. When phytoplankton die and sink, they transfer this carbon to the deep ocean, sequestering it away from the atmosphere. This process, known as the biological pump, has tempered the effect of climate change through the absorption of anthropogenic carbon dioxide. The efficiency of the biological pump – and the ocean’s continued ability to absorb carbon dioxide in the future – will depend on the ability of different phytoplankton groups to adapt to effects of climate change in marine environments, such as warming and acidification. In order to quantify how the cumulative effects of subcellular processes will determine the amount of carbon dioxide phytoplankton use in future oceans, this research tests the adaptability of different phytoplankton groups to the expected conditions in year 2100 and year 2500 oceans.
Carbon fixation in today’s oceans proceeds through CO2-concentration mechanisms (CCMs) that improve the efficiency of carbon fixation by increasing CO2 concentrations at site of carbon fixation. CCMs have evolved independently within different groups of phytoplankton resulting in distinct types of CCMs with convergent functions. Continued anthropogenic CO2 emissions are forcing phytoplankton to adapt to the impacts of climatic change at an accelerating pace. Individual components of CCMs are known to respond to the effects of climate change including pH, the concentration of dissolve inorganic carbon, and temperature. The cumulative response of CCMs at the subcellular level represents the organismal response of phytoplankton to climate change, with direct implications for the efficiency of carbon fixation in future oceans. The primary goal of this project is to quantify the adaptive response of CCMs to the selective drivers of climate change through the experimental evolution of five phytoplankton groups with distinct CCMs, including a diatom, dinoflagellate, green alga, coccolithophore, and a cyanobacterium.
