Increased temperature, rather than elevated CO2, modulates the carbon assimilation of the Arctic kelps Saccharina latissima and Laminaria solidungula

• Main Authors: Iñiguez, Concepcion, Carmona, Raquel, Lorenzo, M Rosario, Niell, F Xavier, Wiencke, Christian, Gordillo, Francisco J L
• Format: Dataset
• Language: English
• Published: PANGAEA 2016
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Arctic; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using CO2calc; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon fixation rate; Chromista; Coast and continental shelf; Dissolved organic carbon release rate; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gross photosynthesis rate; oxygen; Growth/Morphology; Growth rate; Inhibition of carbon fixation; Arctic Ocean; Svalbard; Kongsfjord*; Kongsfjorden; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.870756; https://doi.org/10.1594/PANGAEA.870756

Ocean acidification and warming are affecting with special intensity the Arctic Ocean. Arctic coastal ecosystems are dominated by kelp forests with a high biomass production, which are expected to be directly affected by the increases in CO2 and temperature. This study presents the different physiological responses of the Arctic kelps Saccharina latissima and Laminaria solidungula from Kongsfjorden (Svalbard) cultured at 4 and 9 °C in combination with current (390 ppm) and increased (1200 ppm) levels of atmospheric CO2. Both species were largely unaffected by increased CO2 conditions. Carbon fixation was not influenced by CO2, indicating that photosynthesis was C-saturated at present levels, and 13C isotopic discrimination values from algal tissue suggested no deactivation of carbon concentrating mechanisms at increased CO2 levels. Inhibition of photosynthesis by carbonic anhydrases (CAs) inhibitors highlighted the important role of external CAs in inorganic carbon acquisition in Arctic kelps. Saccharina latissima showed a significantly higher growth rate at 9 °C than at 4 °C, probably due to the decrease in the dark respiration rate observed. Growth rate of L. solidungula was not affected by temperature or CO2, and increases in photosynthesis at 9 °C could be partially related to a higher dissolved organic carbon release rate. The photochemical performance of both species was not altered by any of the treatments. These results suggest that S. latissima might be more benefited than L. solidungula in a future warmer Arctic, while both populations seem to be resilient to higher CO2 concentrations.