Technical Note: Controlled experimental aquarium system for multi-stressor investigation of carbonate chemistry, oxygen saturation, and temperature

• Published in: Biogeosciences
• Main Authors: Bockmon, E. E., Frieder, C. A., Navarro, M. O., White-Kershek, L. A., Dickson, A. G.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Ocean acidification
• Online Access: https://doi.org/10.5194/bg-10-5967-2013; https://www.biogeosciences.net/10/5967/2013/

As the field of ocean acidification has grown, researchers have increasingly turned to laboratory experiments to understand the impacts of increased CO 2 on marine organisms. However, other changes such as ocean warming and deoxygenation are occurring concurrently with the increasing CO 2 concentrations, complicating the understanding of the impacts of anthropogenic changes on organisms. This experimental aquarium design allows for independent regulation of CO 2 concentration, O 2 levels, and temperature in a controlled environment to study the impacts of multiple stressors. The system has the flexibility for a wide range of treatment chemistry, seawater volumes, and study organisms. Control of the seawater chemistry is achieved by equilibration of a chosen gas mixture with seawater using a Liqui-Cel ® membrane contactor. Included as examples, two experiments performed using the system have shown control of CO 2 at values between approximately 500 and 1400 μatm and O 2 at values from 80 to 240 μmol kg −1 . Temperature has been maintained to 0.5 °C or better in the range of 10–17 °C. On a weeklong timescale, the system has achieved variability in pH of less than 0.007 pH units and in oxygen concentration of less than 3.5 μmol kg −1 . Longer experiments, over a month in duration, have been completed with control to better than 0.08 pH units and 13 μmol kg −1 O 2 . The ability to study the impacts of multiple stressors in the laboratory simultaneously, as well as independently, will be an important part of understanding the response of marine organisms to a high-CO 2 world.