2023/05/23 14:00 Dr. Chia-Te Chien(GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany)

Poster:Post date:2023-05-22
NCU IHOS Seminar Announcement

Title:Effects of phytoplankton physiology on the biological carbon pump: the role of variable stoichiometry


Speaker:Dr. Chia-Te Chien

GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany


Place:S-325, Science Building 1

  Earth system climate models (ESCMs) are powerful tools for analyzing variations in climate, while resolving interdependencies between changes in the atmosphere, on land, and in the ocean. In this regard, the dynamic of marine ecosystems is a critical link. On long timescales, it regulates atmospheric CO2 on the basis of biotic uptake of CO2 over vast oceanic regions and due to the export of photosynthetically fixed carbon into the deep ocean, which affects the Earth’s climate. Plankton–ecosystem models are widely applied to understand marine biogeochemical cycles, by estimating fluxes of major elements, e.g., nitrogen, phosphorus, and carbon, as well as the sources and sinks of marine oxygen. However, most of these models lack a sound mechanistic foundation, preventing them from explicitly accounting for the organisms’ regulation of their internal physiological state. Specifically, the carbon : nitrogen : phosphorus (C:N:P) stoichiometry of phytoplankton is still often represented by static (Redfield) ratios, entirely ignoring its highly variable nature, which can affect model sensitivity to the projections of the future carbon pump.
  In this talk, I will present my recent modelling work regarding an optimality-based ecosystem model that considers variable phytoplankton stoichiometry (C:N:P). The new model is capable of reproducing the C:N:P ratios in the marine particulate organic matter (POM) at the global scale. I will show the effects of variable phytoplankton stoichiometry on the current and future marine biological carbon pump. I will also introduce some applications of the Earth system modelling tool, including the reconstruction of paleo marine biogeochemistry, evaluation of the effects of marine microplastic on the carbon pump, and the projection of future marine biogeochemistry under various anthropogenic stressors.
Last modification time:2023-05-22 PM 2:40

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