DMSP production, primary productivity and community composition in new year sea ice in the Weddell Sea

• Main Authors: Bach, Mareike, Flores, Hauke, Peeken, Ilka, Van de Putte, Anton, Stefels, Jacqueline
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Antarctic; Arctic; Pancake; Southern Ocean; Weddell; Weddell Sea; Antarc*; Phytoplankton; Sea ice
• Online Access: https://hdl.handle.net/11370/60d8306b-a946-4d8a-bcd4-937e98733907; https://research.rug.nl/en/publications/60d8306b-a946-4d8a-bcd4-937e98733907; https://www.igsoc.org/wp-content/uploads/2023/06/procabstracts_80.html

Arctic and Antarctic pack ice are a unique habitat for ice-associated microalgae, which provide the basis of the food web through primary production and carbon transfer to higher trophic levels. Additionally, various ice-algal species can produce the secondary metabolite dimethylsulfoniopropionate (DMSP). This sulphur compound is a precursor of the climate-active gas dimethylsulfide (DMS). Several physiological functions of DMSP have been suggested, including functions in stress response such as cryoprotectant or osmolyte. In addition, DMSP functions as a chemical signalling compound for higher trophic levels. However, the concrete physiological role of DMSP is still elusive and it is uncertain how microalgae will adapt to changing conditions in terms of DMSP production. In order to predict higher or lower production of DMSP in the oceans in the future it is important to quantify the production of DMSP relative to growth in ambient communities of sea ice. There have been limited studies investigating combined DMSP and carbon production in sea ice and especially newly formed sea ice in autumn season has been under-sampled. We present results from newly formed sea ice sampled on the RV Polarstern expedition PS129 in March/April 2022 through the Weddell Sea. Biomass, chlorophyll a content and species composition were analysed in ice cores from pancake ice, first year ice, under-ice water and an autumn pancake ice bloom. Incubation experiments at a range of light intensities (photosynthesis-irradiance curve), to which a set of stable isotopes were added, were used to quantify DMSP production, DMSP uptake rates and primary production in the bottom sea ice communities. This comprehensive data set will be used to provide new insights into the Southern Ocean sulphur cycle and phytoplankton dynamics during an atmospherically relevant season, the autumn.