An automated pH-controlled culture system for laboratory-based ocean acidification experiments

• Published in: Limnology and Oceanography: Methods
• Main Authors: McGraw, C, Cornwall, CE, Reid, M, Currie, K, Hepburn, C, Boyd, PW, Hurd, CL, Hunter, K
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Soc Limnology Oceanography 2010
• Subjects: Environmental Sciences; Ecological Applications; Ecological Impacts of Climate Change; Ocean acidification
• Online Access: http://www.aslo.org/; https://doi.org/10.4319/lom.2010.8.686; http://ecite.utas.edu.au/91477

Using a spectrophotometric pH measurement system, an automated 12-tank culture system was developed,which is capable of maintaining pH levels between 7.51 and 8.00 (local, in-situ pH) within 0.02 pH units at15.1C. The precise control of pH in the individual culture tanks was achieved through the addition of CO2-enriched seawater to unamended seawater. A feed-back system, which automatically adjusted the mixing ratioof unamended and CO2-enriched seawater, ensured that the pH in each tank was kept within 0.02 pH units oftarget values. After each tank adjustment, the spectrophotometric pH measurement was combined with a dissolvedinorganic carbon measurement to automatically re-calculate carbonate chemistry in each tank. The systemwas used to study the growth of the geniculate coralline alga Arthrocardia corymbosa at pH levels of 7.52,7.76, and 7.98.