Seawater carbonate chemistry and Microalgal photophysiology and macronutrient distribution in summer sea ice in the Amundsen and Ross Seas, Antarctica

• Main Authors: Torstensson, Anders, Fransson, Agneta, Currie, Kim I, Wulff, Angela, Chierici, Melissa
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2018
• Subjects: Antarctic; Biomass/Abundance/Elemental composition; Coast and continental shelf; Entire community; Field observation; Pelagos; Polar; Primary production/Photosynthesis; Type; Identification; Station label; LATITUDE; LONGITUDE; Section; Core; DEPTH, ice/snow; Irradiance; Salinity; Temperature, water; Ice thickness; Fucoxanthin; Chlorophyll a; Bacteria; Maximum photochemical quantum yield of photosystem II; Light saturation; Electron transport rate efficiency; Maximal electron transport rate, relative; Non photochemical quenching; pH; Carbon, inorganic, dissolved; Nitrate and Nitrite; Silicate; Phosphate; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Partial pressure of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Alkalinity, total; 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; ice algae; Ocean acidification; Sea ice
• Online Access: https://dx.doi.org/10.1594/pangaea.924295; https://doi.pangaea.de/10.1594/PANGAEA.924295

Our study addresses how environmental variables, such as macronutrients concentrations, snow cover, carbonate chemistry and salinity affect the photophysiology and biomass of Antarctic sea-ice algae. We have measured vertical profiles of inorganic macronutrients (phosphate, nitrite + nitrate and silicic acid) in summer sea ice and photophysiology of ice algal assemblages in the poorly studied Amundsen and Ross Seas sectors of the Southern Ocean. Brine-scaled bacterial abundance, chl a and macronutrient concentrations were often high in the ice and positively correlated with each other. Analysis of photosystem II rapid light curves showed that microalgal cells in samples with high phosphate and nitrite + nitrate concentrations had reduced maximum relative electron transport rate and photosynthetic efficiency. We also observed strong couplings of PSII parameters to snow depth, ice thickness and brine salinity, which highlights a wide range of photoacclimation in Antarctic pack-ice algae. It is likely that the pack ice was in a post-bloom situation during the late sea-ice season, with low photosynthetic efficiency and a high degree of nutrient accumulation occurring in the ice. In order to predict how key biogeochemical processes are affected by future changes in sea ice cover, such as in situ photosynthesis and nutrient cycling, we need to understand how physicochemical properties of sea ice affect the microbial community. Our results support existing hypothesis about sea-ice algal photophysiology, and provide additional observations on high nutrient concentrations in sea ice that could influence the planktonic communities as the ice is retreating. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2019) 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 2020-10-30.