Seawater carbonate chemistry and biomarker pigments and phytoplankton community composition in different biogeochemical regions of the Southern Ocean, supplement to: Endo, H; Hattori, Hiroshi; Mishima, Tsubasa; Hashida, Gen; Sasaki, H; Nishioka, Jun; Suzuki, Koji (2017): Phytoplankton community responses to iron and CO2 enrichment in different biogeochemical regions of the Southern Ocean. Polar Biology, 40(11), 2143-2159

• Main Authors: Endo, H, Hattori, Hiroshi, Mishima, Tsubasa, Hashida, Gen, Sasaki, H, Nishioka, Jun, Suzuki, Koji
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2017
• Subjects: Antarctic; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria <20 L; Community composition and diversity; Entire community; Inorganic toxins; Laboratory experiment; Open ocean; Pelagos; Polar; Primary production/Photosynthesis; Temperate; Event label; Type; Experiment; Treatment; Replicate; Salinity; Temperature, water; Alkalinity, total; Alkalinity, total, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; pH; pH, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Partial pressure of carbon dioxide, standard deviation; Chlorophyll a; Fucoxanthin; 19-Hexanoyloxyfucoxanthin; Percentage; Maximum photochemical quantum yield of photosystem II; rbcL gene, copy number, normalized; Light saturated maximum photosynthetic rate per Chlorophyll a; Initial slope of the photosynthesis-irradiance curve; Light saturated maximum photosynthetic rate; Light saturation; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Aragonite saturation state; Calcite saturation state; Cell density; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Austral; Southern Ocean; Antarc*; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.888447; https://doi.pangaea.de/10.1594/PANGAEA.888447

The ongoing rise in atmospheric CO2 concentration is causing rapid increases in seawater pCO2levels. However, little is known about the potential impacts of elevated CO2 availability on the phytoplankton assemblages in the Southern Ocean's oceanic regions. Therefore, we conducted four incubation experiments using surface seawater collected from the subantarctic zone (SAZ) and the subpolar zone (SPZ) in the Australian sector of the Southern Ocean during the austral summer of 2011-2012. For incubations, FeCl3 solutions were added to reduce iron (Fe) limitation for phytoplankton growth. Ambient and high (~750 µatm) CO2 treatments were then prepared with and without addition of CO2-saturated seawater, respectively. Non-Fe-added (control) treatments were also prepared to assess the effects of Fe enrichment (overall, control, Fe-added, and Fe-and-CO2-added treatments). In the initial samples, the dominant phytoplankton taxa shifted with latitude from haptophytes to diatoms, likely reflecting silicate availability in the water. Under Fe-enriched conditions, increased CO2 level significantly reduced the accumulation of biomarker pigments in haptophytes in the SAZ and AZ, whereas a significant decrease in diatom markers was only detected in the SAZ. The CO2-related changes in phytoplankton community composition were greater in the SAZ, most likely due to the decrease in coccolithophore biomass. Our results suggest that an increase in CO2, if it coincides with Fe enrichment, could differentially affect the phytoplankton community composition in different geographical regions of the Southern Ocean, depending on the locally dominant taxa and environmental conditions. : 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 2018-04-11.