Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 12, 713-721, 2015
https://doi.org/10.5194/bg-12-713-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Technical note
05 Feb 2015
Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system
C. D. MacLeod1, H. L. Doyle2, and K. I. Currie2,3 1Department of Zoology, University of Otago, Dunedin, New Zealand
2Department of Chemistry, University of Otago, Dunedin, New Zealand
3National Institute of Water and Atmospheric Research (NIWA), Dunedin, New Zealand
Abstract. This article describes a potentiometric ocean acidification simulation system which automatically regulates pH through the injection of 100% CO2 gas into temperature-controlled seawater. The system is ideally suited to long-term experimental studies of the effect of acidification on biological processes involving small-bodied (10–20 mm) calcifying or non-calcifying organisms. Using hobbyist-grade equipment, the system was constructed for approximately USD 1200 per treatment unit (tank, pH regulation apparatus, chiller, pump/filter unit). An overall tolerance of ±0.05 pHT units (SD) was achieved over 90 days in two acidified treatments (7.60 and 7.40) at 12 °C using glass electrodes calibrated with synthetic seawater buffers, thereby preventing liquid junction error. The performance of the system was validated through the independent calculation of pHT (12 °C) using dissolved inorganic carbon and total alkalinity data taken from discrete acidified seawater samples. The system was used to compare the shell growth of the marine gastropod Zeacumantus subcarinatus infected with the trematode parasite Maritrema novaezealandensis with that of uninfected snails at pH levels of 7.4, 7.6, and 8.1.

Citation: MacLeod, C. D., Doyle, H. L., and Currie, K. I.: Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system, Biogeosciences, 12, 713-721, https://doi.org/10.5194/bg-12-713-2015, 2015.
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Short summary
This article describes a low-cost, easily set-up ocean acidification simulation system that reliably mimics the effects of elevated atmospheric carbon dioxide on seawater chemistry. The accessible design of this system, along with our suggestions for the validation of pH control and characterisation of seawater chemistry, will enable researchers on a limited budget to generate high-quality, repeatable data documenting the response of marine organisms to ocean acidification.
This article describes a low-cost, easily set-up ocean acidification simulation system that...
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