Phytoplankton Ecophysiology and Biogeochemistry

• Our work on nitrogen isotopes in the Southern Ocean aims to inform the interpretation of paleo proxies on the strength of the biological carbon pump during glacial and interglacial cycles.
• Our work on N₂ fixing organisms will inform biogeochemical modelers on current and projected future productivity of our oceans
• The work on marine productivity will inform ecologists, physiologists and numerical modelers on processes affecting the base of the marine food web.
• We further hope that our work on the toxic dinoflaggelate Karenia brevis, a Gulf of Mexico red tide organism, will inform decision makers and ecosystem managers to better understand and predict the socio-economic impact of this organism in the current and future ocean.

• Our Nature communications artice is out! 11/22: Phosphate limitation intensifies negative effects of ocean acidification on globally important nitrogen fixing cyanobacterium.  https://www.nature.com
• New publication 11/22: Application-specific optimal model weighting of global climate models: A red tide example.https://www.sciencedirect.com/
• 10/22: We are hosting a new graduate student from the FSUCML (marinelab), Benton from Dr. Schantz lab and his UROP student in our lab to work on Karenia brevis related research.
• 09/22: Three new UROP students, Angelique, Ava and Ben accepted our offer to join the lab! They will be working with Ana and Jared either on mixotrophy in Karenia brevis or on our Southern Ocean nitrate isotope project.
• 09/22: A new student intern, Jacqueline (Penny), started in the lab and will be working with Maggie on Antarctic diatoms.
• New publication 09/22: Taxon-specific phytoplankton growth, nutrient utilization and light limitation in the oligotrophic Gulf of Mexico.  https://academic.oup.com
• 08/22: Our new graduate student Margaret (Maggie) Baker arrived!
• New publication  05/22: Inorganic carbon acquisition by aquatic primary producers. https://onlinelibrary.wiley.com
• New publication 05/22: Earth system models for regional environmental management of red tide: Prospects and limitations of current generation models and next generation development. https://link.springer.com
• New student led publication 02/22: Effects of spectral light quality on the growth, productivity, and elemental ratios in differently pigmented marine phytoplankton species. https://link.springer.com
• New publication 01/22: Prescreening-based subset selection for improving predictions of Earth system models with application to regional prediction of red tide https://www.frontiersin.org

The Kranz lab is located on the main campus in Tallahassee. Our lab is on the 5th floor of the new EOA building and has an open concept which will enhance interaction of  graduate and undergraduate students between the different groups located here. We have designated lab spaces for culture work, chemical handling, a dark room for microscopy and light sensitive analysis, a wal- in cold room and a make-shift clean room (until the clean room is fully functional).

some pictures of our lab space here

We regularly conduct field research - usually on research vessels.      

some pictures of recent cruises can be found here

Despite their microscopic size, phytoplankton are responsible for about half of the global primary production. This diverse group of organisms is an integral component of the global biosphere, driving biogeochemical cycles of important elements while exporting large amounts of carbon to deep waters and sediments. In coastal regions, these organisms also have a socioeconomical significance as they affect water quality and fisheries. Consequently, understanding the current distribution and productivity of phytoplankton in ecological important ocean basins, and assessing how and why the phytoplankton community may respond to perturbations driven by environmental change, constitutes a major challenge in aquatic research. We aim to understand community composition and productivity of phytoplankton in the World's oceans. For this, we study phytoplankton communities and monoclonal cultures under different environmental scenarios such as changes in temperature, light intensit, CO₂ concentrations and/or availability of iron. A suite of in vivo assays based on standard and cutting-edge techniques provide a mechanistic understanding of the observed responses. Processes such as productivity, cellular composition, photosynthetic efficiency, the modes of carbon and nutrient acquisition and isotope fractionation are investigated on multiple cellular levels. Laboratory studies with isolated monoclonal cultures and research cruises increase our process understanding of how and why phytoplankton, found in the different regions of the World's oceans, respond to environmental stressors.