Dataset: Comeau 2017 Biogeosciences: calcification and chemistry

See Comeau et al. (2017) for a detailed overview of the methodology.

Locations:

UCB Gump Research Station Moorea, French Polynesia
Hawaii Institute of Marine Biology, Kaneohe Bay, O’ahu, HI

Methodology: 

For the three experiments, pH on the total scale (pHT) was measured daily using a portable pH meter (Orion 3-stars, Thermo-Scientific, USA) fitted with a DG 115-SC pH probe (Mettler Toledo, Switzerland) calibrated every other day with Tris/HCl buffers (Dickson et al., 2007). pHT also was mea- sured every 2 weeks spectrophotometrically using m-cresol dye (Dickson et al., 2007). Mean values of pHT measured spectrophotometrically and using a pH electrode differed by < 0.02 pH units. Total alkalinity (AT ) was measured using open-cell potentiometric titrations (Dickson et al., 2007) on ∼ 50 g samples of seawater collected every 2–3 days. Parameters of the carbonate system in seawater were determined with the seacarb R package (Gattuso et al., 2015) using measured values of pHT , AT , temperature, and salinity. 

Net community calcification (Gnet) in the flumes was mea- sured using the total alkalinity anomaly method (Chisholm and Gattuso 1991), and net community primary production (Pnet) was measured using oxygen sensors (TROLL 9500, In-Situ) that measured the O2 concentration at 60 s intervals with an accuracy of 0.2 mg L−1.