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Non-Redfield Marine Elemental Stoichiometry: Its Manifestations and Why It Matters
UNH Dept. of Earth Sciences and Ocean Process Analysis Laboratory
Are the oceans turning into deserts? Rising ocean temperatures, surface water stratification, and decreasing vertical inputs of nutrients are predicted to cause an expansion of warm, nutrient deplete ecosystems of the subtropical gyres at the expense of more nutrient rich, colder waters in the latest class of Earth System Model projections. Such an expansion is predicted to negatively affect a triad of key ocean biogeochemical features: lower phytoplankton biomass, lower primary productivity, and lower carbon export (aka the biological carbon pump). Due to the inextricably linked marine carbon, nitrogen, and phosphorus cycles first identified by Alfred Redfield in 1934, these combined effects should decrease the strength of the ocean CO2 sink in the climate system. Thus, the ocean biogeochemical and ecosystem response to climate warming suggests a positive feedback to further accumulations of CO2 in the Earth’s atmosphere. However, it is now recognized that phytoplankton communities contain immense diversity and adaptability that could render the ocean biogeochemical response at least partially resilient to global changes through the shifting effects of changes to marine elemental stoichiometry in the future ocean. I will review the current state of the field with regards to understanding these ‘non-Redfield’ stoichiometry effects as the ocean biogeochemical community moves past the enduring ‘Redfield stoichiometry’ paradigm of the past 85 years.
Dr. Robert Letscher joined UNH in Fall 2017 as an Assistant Professor of Chemical Oceanography in the Department of Earth Sciences and the Ocean Process Analysis Laboratory in EOS. His research broadly investigates marine biogeochemical processes at regional to global scales across the world ocean. He is a developer of the marine biogeochemical and ecosystem model within the NSF-funded Community Earth System Model and DOE-funded Energy Exascale Earth System Model. Observationally his work has taken him to the Arctic Ocean to study the fate of organic matter washing off the tundra and more recently the ocean subtropics at the ALOHA time-series station near Hawaii to quantify ‘marine snot’. A unifying theme for these diverse pursuits is the quantification and representation of non-Redfield marine elemental cycling processes operating at global scales.
