Antarctic phytoplankton in response to environmental change studied by a synergistic approach using multi- and hyper-spectral satellite data

• Applicants: Professorin Dr. Astrid Bracher; Professor Dr. John Philip Burrows
• Subject Area: Oceanography
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257450530

Climate models indicate that the Southern Ocean will significantly be affected and impacted by changes in temperature and pH in the near future resulting from the tropospheric release of greenhouse gases and in particular carbon dioxide from fossil fuel combustion. Such changes will impact on the phytoplankton composition and thus affect the cycling of carbon, nitrogen and related compounds. The objectives of this interdisciplinary project are to assess the spatial and temporal variability of phytoplankton types in the Southern Ocean, to better understand their different in the Southern Ocean ecosystem, and to improve our quantitative estimates of the contribution of Antarctic phytoplankton to the global carbon cycle. Using a unique combination of data from two different satellite instruments, the concentration of different phytoplankton types will be assessed for the first time in the Southern Ocean with reasonable temporal and spatial coverage. This synergistic method will be generic and applicable to similar upcoming satellite missions and therefore secure a perspective for a unique phytoplankton type data set covering decades. The total phytoplankton biomass data will be retrieved by adaptation to the Antarctic conditions from multi-spectral imaging instruments, whereas the fractions of the most important phytoplankton types within the total biomass will be determined from the analysis of their characteristic absorption features in hyper-spectral satellite measurements using the PhytoDOAS method developed by our research team. The resulting long term satellite data set is a necessary benchmark for future change. It will then be used to study the Antarctic phytoplankton varibility over the last ten years and their correlation with changing environmental factors. In addition, our phytoplankton composition data set will be used to evaluate in the Southern Ocean the performance of a ecosystem model which assesses the biogeography of phytoplankton types based on their physiological traits in a modeled ocean. Recommendations for improved model parameterizations will result from this research exercise. With this long-term phytoplankton type data set and the acquired knowledge of Antarctic phytoplankton variability, we will have a basis to assess the influence of climate change on the Southern Ocean.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• International Connection: Australia, USA
• Participating Persons: Dr. Stephanie Dutkiewicz; Dr. Oliver Huhn; Dr. Kerstin Jerosch; Dr. Robert Johnson; Professor Dr. Ulf Karsten; Dr. Scarlett Trimborn