Coping with a changing Arctic: mechanisms of acclimation in the brown seaweed Saccharina latissima from Spitsbergen - raw data to 2-factor experiments with field material from Kongsfjorden, June/July 2019

Polar Regions are facing rapid temperature increase. Combined with other factors temperature increase might have a strong impact on foundation species in Arctic shallow-water coastal ecosystems, such as the abundant kelp Saccharina latissima. We ran two short-term 2-factor experiments with field samples from Kongsfjorden (Svalbard) to reveal the impact of temperature increase in summer combined with hyposalinity (temperature × salinity) or nutrient enrichment (temperature × nutrients) and analyzed different biochemical and physiological parameters. The experiments were conducted with field samples at AWIPEV Station in Ny-Ålesund, Svalbard (Spitsbergen) in June/July 2019. As physiological parameter, size and the maximum photosynthetic quantum yield of photosystem II (Fv/Fm; Imaging-PAM, Walz GmbH Mess- und Regeltechnik, Effeltrich, Germany) were monitored every second day. For growth, the size of the algal discs was analyzed with ImageJ (Version 1.52a). For better comparison of the physiological parameters, Fv/Fm and growth the initial size of the different treatments was adjusted to 100% and size of each sample as % of initial was calculated. The C:N ratio, total nitrogen and total carbon content were analyzed with an elemental analyzer. Mannitol, as well as absolute pigment concentrations were analyzed using a HPLC. The de-expoxidation state of the xanthophyll cycle (DPS) and chlorophyll a : accessory pigment ratio calculated afterwards. Phlorotannins were analyzed using the photometric Folin-Ciocalteu method.