Microsensor studies on Padina from a natural CO2 seep: implications of morphology on acclimation to low pH, supplement to: Hofmann, Laurie C; Fink, Artur; Bischof, Kai; de Beer, Dirk (2015): Microsensor studies on Padina from a natural CO2 seep: implications of morphology on acclimation to low pH. Journal of Phycology, 51(6), 1106-1115

• Main Authors: Hofmann, Laurie C, Fink, Artur, Bischof, Kai, de Beer, Dirk
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2015
• Subjects: Benthos; Bottles or small containers/Aquaria <20 L; Chlorophyta; Chromista; CO2 vent; Coast and continental shelf; Field experiment; Macroalgae; Ochrophyta; Padina australis; Primary production/Photosynthesis; Single species; South Pacific; Temperate; Type; Species; Registration number of species; Uniform resource locator/link to reference; Figure; Site; Treatment; Identification; Run Date/Time; Distance; Oxygen; Oxygen, standard error; Location; Replicate; Gross photosynthesis rate, oxygen; Salinity; Temperature, water; pH; Carbon, inorganic, dissolved; 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; Potentiometric; Calculated using seacarb after Nisumaa et al. 2010; Biological Impacts of Ocean Acidification BIOACID; Ocean Acidification International Coordination Centre OA-ICC; Hofmann; Laurie; Pacific; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.860218; https://doi.pangaea.de/10.1594/PANGAEA.860218

Low seawater pH can be harmful to many calcifying marine organisms, but the calcifying macroalgae Padina spp. flourish at natural submarine carbon dioxide seeps where seawater pH is low. We show that the microenvironment created by the rolled thallus margin of Padina australis facilitates supersaturation of CaCO3 and calcifi-cation via photosynthesis-induced elevated pH. Using microsensors to investigate oxygen and pH dynamics in the microenvironment of P. australis at a shallow CO2 seep, we found that, under saturating light, the pH inside the microenvironment (pHME) was higher than the external seawater (pHSW) at all pHSW levels investigated, and the difference (i.e., pHME-pHSW) increased with decreasing pHSW (0.9 units at pHSW 7.0). Gross photosynthesis (Pg) inside the microenvironment increased with decreasing pHSW, but algae from the control site reached a threshold at pH 6.5. Seep algae showed no pH threshold with respect to Pg within the pHSW range investigated. The external carbonic anhydrase (CA) inhibitor, acetazolamide, strongly inhibited Pg of P. australis at pHSW 8.2, but the effect was diminished under low pHSW (6.4-7.5), suggesting a greater dependence on membrane-bound CA for the dehydration of HCO3- ions during dissolved inorganic carbon uptake at the higher pHSW. In comparison, a calcifying green alga, Halimeda cuneata f. digitata, was not inhibited by AZ, suggesting efficient bicarbonate transport. The ability of P. australis to elevate pHME at the site of calcification and its strong dependence on CA may explain why it can thrive at low pHSW. : 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 2016-05-05.