Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps, supplement to: Vogel, Nikolas; Fabricius, Katharina Elisabeth; Strahl, Julia; Noonan, Sam; Wild, Christian; Uthicke, Sven (2015): Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps. Limnology and Oceanography, 60(1), 263-275

• Main Authors: Vogel, Nikolas, Fabricius, Katharina Elisabeth, Strahl, Julia, Noonan, Sam, Wild, Christian, Uthicke, Sven
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2015
• Subjects: Benthos; Biomass/Abundance/Elemental composition; Calcification/Dissolution; Chlorophyta; CO2 vent; Coast and continental shelf; Field experiment; Field observation; Halimeda digitata; Halimeda opuntia; Light; Macroalgae; Plantae; Primary production/Photosynthesis; Respiration; Single species; South Pacific; Tropical; Site; Species; Treatment; Calcification rate of calcium carbonate; Net photosynthesis rate, oxygen; Respiration rate, oxygen; Gross photosynthesis rate, oxygen; Carbon, total; Carbon, organic, total; Carbon, inorganic, total; Carbon, organic total/Carbon, inorganic total; δ13C; pH; pH, standard deviation; Temperature, water; Temperature, water, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Partial pressure of carbon dioxide, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbon dioxide; Carbon dioxide, standard deviation; Calcite saturation state; Calcite saturation state, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Salinity; Carbonate system computation flag; Fugacity of carbon dioxide water at sea surface temperature wet air; Experiment; Potentiometric; Calculated using CO2calc; Potentiometric titration; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Pacific; Sven; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.846875; https://doi.pangaea.de/10.1594/PANGAEA.846875

We investigated ecological, physiological, and skeletal characteristics of the calcifying green alga Halimeda grown at CO2 seeps (pHtotal ~ 7.8) and compared them to those at control reefs with ambient CO2 conditions (pHtotal ~ 8.1). Six species of Halimeda were recorded at both the high CO2 and control sites. For the two most abundant species Halimeda digitata and Halimeda opuntia we determined in situ light and dark oxygen fluxes and calcification rates, carbon contents and stable isotope signatures. In both species, rates of calcification in the light increased at the high CO2 site compared to controls (131% and 41%, respectively). In the dark, calcification was not affected by elevated CO2 in H. digitata, whereas it was reduced by 167% in H. opuntia, suggesting nocturnal decalcification. Calculated net calcification of both species was similar between seep and control sites, i.e., the observed increased calcification in light compensated for reduced dark calcification. However, inorganic carbon content increased (22%) in H. digitata and decreased (-8%) in H. opuntia at the seep site compared to controls. Significantly, lighter carbon isotope signatures of H. digitata and H. opuntia phylloids at high CO2 (1.01 per mil [parts per thousand] and 1.94 per mil, respectively) indicate increased photosynthetic uptake of CO2 over HCO3- potentially reducing dissolved inorganic carbon limitation at the seep site. Moreover, H. digitata and H. opuntia specimens transplanted for 14 d from the control to the seep site exhibited similar delta13C signatures as specimens grown there. These results suggest that the Halimeda spp. investigated can acclimatize and will likely still be capable to grow and calcify in inline image conditions exceeding most pessimistic future CO2 projections. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2015) 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 is 2015-06-01.