Novel methodology for in situ carbon dioxide enrichment of benthic ecosystems

• Published in: Limnology and Oceanography: Methods
• Main Authors: Campbell, Justin E., Fourqurean, James W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2011
• Subjects: Ocean acidification
• Online Access: http://dx.doi.org/10.4319/lom.2011.9.97; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flom.2011.9.97; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lom.2011.9.97

Future climate change will likely represent a major stress to shallow aquatic and coastal marine communities around the world. Most climate change research, particularly in regards to increased pCO 2 and ocean acidification, relies on ex situ mesocosm experimentation, isolating target organisms from their environment. Such mesocosms allow for greater experimental control of some variables, but can often cause unrealistic changes in a variety of environmental factors, leading to “bottle effects.” Here we present an in situ technique of altering dissolved pCO 2 within nearshore benthic communities (e.g., macrophytes, algae, and/or corals) using submerged clear, open‐top chambers. Our technique utilizes a flow‐through design that replicates natural water flow conditions and minimizes caging effects. The clear, open‐top design additionally ensures that adequate light reaches the benthic community. Our results show that CO 2 concentrations and pH can be successfully manipulated for long durations within the open‐top chambers, continuously replicating forecasts for the year 2100. Enriched chambers displayed an average 0.46 unit reduction in pH as compared with ambient chambers over a 6‐month period. Additionally, CO 2 and HCO 3 − concentrations were all significantly higher within the enriched chambers. We discuss the advantages and disadvantages of this technique in comparison to other ex situ mesocosm designs used for climate change research.