Technical Note: A minimally invasive experimental system for <i>p</i>CO<sub>2</sub> manipulation in plankton cultures using passive gas exchange (atmospheric carbon control simulator)

Abstract

Abstract. As research into the biotic effects of ocean acidification has increased, the methods for simulating these environmental changes in the laboratory have multiplied. Here we describe the atmospheric carbon control simulator (ACCS) for the maintenance of plankton under controlled pCO2 conditions, designed for species sensitive to the physical disturbance introduced by the bubbling of cultures and for studies involving trophic interaction. The system consists of gas mixing and equilibration components coupled with large-volume atmospheric simulation chambers. These chambers allow gas exchange to counteract the changes in carbonate chemistry induced by the metabolic activity of the organisms. The system is relatively low cost, very flexible, and when used in conjunction with semi-continuous culture methods, it increases the density of organisms kept under realistic conditions, increases the allowable time interval between dilutions, and/or decreases the metabolically driven change in carbonate chemistry during these intervals. It accommodates a large number of culture vessels, which facilitate multi-trophic level studies and allow the tracking of variable responses within and across plankton populations to ocean acidification. It also includes components that increase the reliability of gas mixing systems using mass flow controllers.

High pCO2 does not alter the thermal plasticity of developing Pacific herring embryos during a marine heatwave

“…Discrete seawater samples (25 ml) were taken every third day from each replicate tank ( n =5 samples per heatwave replicate; n =6 samples per ambient replicate) for direct measurements of pH T and DIC following methods described by Love et al (2017) . Temperature, pH NIST and salinity were recorded at the time of sampling using the handheld electrode.…”

Temperature and salinity, not acidification, predict near-future larval growth and larval habitat suitability of Olympia oysters in the Salish Sea

“…Salinities were achieved by manually mixing preequilibrated 0.35 µm filtered seawater (FSW) with concentrated brine (FSW enhanced with Marine Mix instant ocean salt) or simulated river water (deionized water enriched with sodium bicarbonate to 600µeq/L 61 alkalinity). Acidification was achieved by individually bubbling CO 2 controlled air into treatment cultures using an air compressor, CO 2 scrubber, and eight mass flow controllers mixing pure CO 2 with CO 2 -free air for treatment conditions (system described in a 2017 technical note 62 ). The non-uniform multifactorial spread of this design allowed us to analyze predictor variables as continuous gradients and interpolate responses between treatment values, rather than conduct treatment level comparisons.…”

Direct and indirect effects of elevated CO2 are revealed through shifts in phytoplankton, copepod development, and fatty acid accumulation

“…Experiments were conducted at the Shannon Point Marine Center (SPMC) in Anacortes, Washington. Control of the carbonate chemistry of all cultures and experiments was achieved using an atmospheric carbon control simulator (ACCS) that has been described in detail [ 45 ]. In short, the ACCS combines CO 2 -free air with pure CO 2 using mass flow controllers to achieve the treatment levels; these air-CO 2 mixtures are then used to bubble reservoirs of 0.2-μm filtered, UV-exposed natural seawater (salinity 28–32) to equilibrate the seawater to target p CO 2 conditions, and distributed to sealed atmospheric simulation chambers where cultures and experimental vessels are maintained.…”

“…Full carbonate system parameters were calculated using CO2sys [ 47 ] using the constants of Mehrbach et al [ 48 ] refit by Dickson and Millero [ 49 ] and the total pH scale. Full details on carbonate chemistry methods have been previously described [ 45 ].…”