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Joana Tavares

I study how phytoplankton are affected by human activities. Phytoplankton take in elements such as nitrogen, phosphorus and iron and use sunlight to combine these nutrients with CO2,  new organic compounds. Marine phytoplankton are responsible for half of the primary production on Earth, and by doing so they serve as the basis of virtually all marine food webs. Over long time scales, phytoplankton also help regulate Earth’s climate by transporting carbon into the deep ocean and into marine sediments.


I am particularly interested in the role that ships may be playing as a source of nutrients and/or toxins for phytoplankton in both coastal and open ocean areas. In general, the phytoplankton have access to nutrient inputs near the coast. In contrast, the sources of nutrients that fertilize open ocean areas are fewer, irregular and chemically incomplete.  We know that the combustion of fossil fuels releases chemical elements that can serve as fertilizers for phytoplankton, which leads us to ask: Could ships be fertilizing certain ocean areas? What is the relative importance of emissions from ships’ engines as sources of nutrients for the phytoplankton? And could ship emissions also cause the decline of certain phytoplankton groups? I aim to investigate the effects of ship emissions on various phytoplankton communities, using analytical and experimental methods, including remote sensing data and mesocosm incubations. I combine my results with existing chemical transport models and shipping inventories to map current and future impacts of shipping on marine productivity and carbon sequestration rates. Ultimately, I hope to develop tools that can be used to improve integrated coastal management and global environmental sustainability. My research is supported by a Nevin Graduate Endowment Fellowship, a UCI Diversity Recruitment Doctoral Fellowship and by NASA’s Future Investigators in NASA Earth and Space Science and Technology (FINESST) Program. 

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