Two Southern Ocean diatoms are more sensitive to ocean acidification and changes in irradiance than the prymnesiophyte Phaeocystis antarctica, supplement to: Trimborn, Scarlett; Thoms, Silke; Brenneis, Tina; Heiden, Jasmin; Beszteri, Sara; Bischof, Kai (2017): Two Southern Ocean diatoms are more sensitive to ocean acidification and changes in irradiance than the prymnesiophyte Phaeocystis antarctica. Physiologia Plantarum

• Main Authors: Trimborn, Scarlett, Thoms, Silke, Brenneis, Tina, Heiden, Jasmin, Beszteri, Sara, Bischof, Kai
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2017
• Subjects: Antarctic; Bottles or small containers/Aquaria <20 L; Chaetoceros debilis; Chromista; Fragilariopsis kerguelensis; Growth/Morphology; Haptophyta; Laboratory experiment; Ochrophyta; Open ocean; Pelagos; Phaeocystis antarctica; Phytoplankton; Polar; Primary production/Photosynthesis; Single species; Type; Species; Registration number of species; Uniform resource locator/link to reference; Treatment; Partial pressure of carbon dioxide water at sea surface temperature wet air; Growth rate; Growth rate, standard deviation; Carbon, organic, particulate, per cell; Carbon, organic, particulate, standard deviation; Carbon/Nitrogen ratio; Carbon/Nitrogen ratio, standard deviation; Maximum photochemical quantum yield of photosystem II; Maximum photochemical quantum yield of photosystem II, standard deviation; Yield; Yield, standard deviation; Irradiance; Electron transport rate; Electron transport rate, standard deviation; Non photochemical quenching; Non photochemical quenching, standard deviation; Temperature, water; Salinity; Partial pressure of carbon dioxide, standard deviation; Carbon dioxide; Carbon dioxide, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; pH; pH, standard deviation; Carbonate system computation flag; Fugacity of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Aragonite saturation state; Calcite saturation state; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Southern Ocean; Antarc*; Antarctica; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.874781; https://doi.pangaea.de/10.1594/PANGAEA.874781

To better understand the impact of ocean acidification (OA) and changes in light availability on Southern Ocean phytoplankton physiology, we investigated the effects of pCO2 (380 and 800 µatm) in combination with low and high irradiance (20 or 50 and 200 µmol photons/m2/s) on growth, particulate organic carbon (POC) fixation and photophysiology in the three ecologically relevant species Chaetoceros debilis, Fragilariopsis kerguelensis and Phaeocystis antarctica. Irrespective of the light scenario, neither growth nor POC per cell was stimulated by OA in any of the tested species and the two diatoms even displayed negative responses in growth (e.g. C. debilis) or POC content (e.g. F. kerguelensis) under OA in conjunction with high light. For both diatoms, also maximum quantum yields of PSII (Fv/Fm) were decreased under these conditions, indicating lowered photochemical efficiencies. To counteract the negative effects by OA and high light, the two diatoms showed diverging photoacclimation strategies. While cellular chlorophyll a and fucoxanthin contents were enhanced in C. debilis to potentially maximize light absorption, F. kerguelensis exhibited reduced chlorophyll a per cell, increased disconnection of antennae from photosystem II reaction centers and strongly lowered absolute electron transport rates (ETR). The decline in ETRs in F. kerguelensis might be explained in terms of different species-specific strategies for tuning the available flux of adenosine triphosphate and nicotinamide adenine dinucleotide phosphate. Overall, our results revealed that P. antarctica was more tolerant to OA and changes in irradiance than the two diatoms, which may have important implications for biogeochemical cycling. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2016) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2017-04-21.