Seawater carbonate chemistry and algal abundance, growth and flourometry data of a late summer suface sea ice community

• Main Authors: McMinn, Andrew, Müller, Marius N, Martin, Andrew, Ugalde, Sarah C, Lee, Shihong, Castrisios, Katerina, Ryan, Ken G
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; standard deviation; Antarctic; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Biovolume; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Cell counts; Chlorophyll a; Coast and continental shelf; Entire community; EXP; Experiment; Experiment duration; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Index; Maximal electron transport rate; relative; Maximum photochemical quantum yield of photosystem II; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.875707; https://doi.org/10.1594/PANGAEA.875707

Annual fast ice at Scott Base (Antarctica) in late summer contained a high biomass surface community of mixed phytoflagellates, dominated by the dinoflagellate, Polarella glacialis. At this time of the year, ice temperatures rise close to melting point and salinities drop to less than 20. At the same time, pH levels can rise above 9 and nutrients can become limiting. In January 2014, the sea ice microbial community from the top 30 cm of the ice was exposed to a gradient of pH and CO2 (5 treatments) that ranged from 8.87 to 7.12 and 5-215 µmol CO2 kg?1, respectively, and incubated in situ. While growth rates were reduced at the highest and lowest pH, the differences were not significant. Likewise, there were no significant differences in maximum quantum yield of PSII (Fv/Fm) or relative maximum electron transfer rates (rETRmax) among treatments. In a parallel experiment, a CO2 gradient of 26-230 µmol CO2 kg?1 (5 treatments) was tested, keeping pH constant. In this experiment, growth rates increased by approximately 40% with increasing CO2, although differences among treatments were not significant. As in the previous experiment, there was no significant response in Fv/Fm or rETRmax. A synchronous grazing dilution experiment found grazing rates to be inconclusive These results suggest that the summer sea ice brine communities were not limited by in situ CO2 concentrations and were not adversely affected by pH values down to 7.1.