Netherlands Polar Data Center

Summary

Large scale, satellite derived data demonstrate changing marine primary productivity in the Western Antarctic Peninsula (WAP) region due to regional warming. However, field based primary productivity (PP) measurements are needed to support and verify this, and ultimately to understand the biogeochemical and ecological impacts. The common 14C, or 13C incorporation techniques require bottle incubations which restrict the number of measurements. As a result, these techniques are not suitable for measuring at high temporal frequency. A detailed perception of climate change impacts would therefore benefit from the development and implementation of non-intrusive PP estimates. Fast Repetition Rate fluorometry (FRRF) is increasingly used in Antarctic regions to generate high-resolution estimates of gross PP. However, research is needed to accurately convert FRRF derived electron transport rates (ETR) into carbon fixation for phytoplankton key species and natural assemblages. In the proposed study we will develop this non-intrusive method to estimate PP at the Rothera time series station RaTS, WAP. We will first assess ETR/Carbon fixation relationships under relevant conditions (irradiance, temperature, nutrient (including Fe)), using isolated key species from the area. To validate fluorescence based productivity estimates, two full season field campaigns will be executed where 14C-carbon incorporation, FRRF/ETR, and phytoplankton composition will be followed as a function of environmental conditions. The proposed project will facilitate implementation of automated FRRF technology at the RaTS site. Furthermore, it will yield two full seasons of high resolution primary production data, which will provide essential information on the factors that regulate PP in this rapidly changing region.

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