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

Abstract

As the field of ocean acidification has grown, researchers have increasingly turned to laboratory experiments to understand the impacts of increased CO₂ on marine organisms. However, other changes such as ocean warming and deoxygenation are occurring concurrently with the increasing CO₂ concentrations, complicating the understanding of the impacts of anthropogenic changes on organisms. This experimental aquarium design allows for independent regulation of CO₂ concentration, O₂ 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 CO₂ at values between approximately 500 and 1400 μatm and O₂ 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 O₂. 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-CO₂ world

Exploring local adaptation and the ocean acidification seascape – studies in the California Current Large Marine Ecosystem

“…For example, organisms in the CCLME will face changes in exposures to both the severity and frequency of low pH and saturation state conditions (Hauri et al, 2013), with impacts that can interact with exposures to declining oxygen concentrations (Rykaczewski andDunne 2010, Cocco et al, 2012). While capacity for resolving mean state vs. variability impacts and interactions between multiple stressors remains a limiting factor in the field, development of new experimental systems (Bockmon et al, 2013) can enable experimental treatments that mimic exposure regimes that organisms are observed and forecasted to face in situ. Such advances will be crucial to making more robust forecasts regarding the ecological consequences of future ocean change (Boyd, 2011;Harvey et al, 2013).…”

“…For coastal regions, the scientific community is just now assessing the longer-term variability in pH. Recent analyses of long-term data sets indicate that pH is changing rapidly in coastal Washington (Wootton and Pfister, 2012), in coastal upwelling zones along the US Pacific coast (Harris et al, 2013;Chan et al, 2014), at a coastal region in the Netherlands (Provoost et al, 2010), and in the Monterey Bay area where low pH water is associated with low oxygen water masses that reach the shallow, nearshore regions (Booth et al, 2012). Cruise data have provided snapshots of carbonate chemistry along the coast of the CCLME (Feely et al, 2008), and suggested that at some locations in northern California, undersaturated waters shoaled in the inner shelf.…”

Environmental pH, O2 and Capsular Effects on the Geochemical Composition of Statoliths of Embryonic Squid Doryteuthis opalescens

“…Several step-wise changes in the system level setting were conducted during the course of each experiment to maintain stable environmental conditions [67], and thus, data were not normally distributed. Treatment conditions were distinct for each experiment with respect to pH, Ω aragonite and [O 2 ], but not for temperature and alkalinity (Wilcoxon test; Table 1).…”

Polyp flats, a new system for experimenting with jellyfish polyps, with insights into the effects of ocean acidification

“…The performance assessment presented in this study attests to the suitability and reliability of this system to meet the current needs of environmental laboratory research on jellyfish polyps, taking advantage of the benefits of working in a continuous flow system. This prototype adds to the current pool of newly designed devices (e.g., Fangue et al 2010;McGraw et al 2010;Bockmon et al 2013;Hoffmann et al 2013) aimed at providing better tools for testing the effects of acidification and other environmental stressors in marine organisms, a discipline that has recently been identified as research front number one in Ecology and Environmental Sciences (King and Pendlebury 2013).…”