MEPS 340:9-16 (2007)  -  doi:10.3354/meps340009

Exposure to carbon dioxide-rich seawater is stressful for some deep-sea species: an in situ, behavioral study

D. Thistle1,*, L. Sedlacek1, K. R. Carman2, J. W. Fleeger2, P. G. Brewer3, J. P. Barry3

1Department of Oceanography, Florida State University, Tallahassee, Florida 32306-4320, USA
2Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803-1725, USA
3Monterey Bay Aquarium Research Institute, Sandholdt Road, Moss Landing, California 95039-9644, USA

ABSTRACT: Since the beginning of the industrial revolution, the concentration of the greenhouse gas carbon dioxide in the atmosphere has increased from 275 to 370 ppm; the increase is thought to have caused much of the rise in global temperature that has occurred during the same period. A means of mitigating its effects is to collect industrial carbon dioxide and sequester it in the deep ocean. Knowledge of effects of such sequestration on deep-sea organisms is crucial to evaluation of the wisdom of deep-ocean sequestration. We therefore tested deep-sea animals for indications that exposure to carbon dioxide-rich seawater is stressful. Our study site was at 3087 m depth off the coast of central California (36°41.91’N, 123°0.14’W). We deployed liquid carbon dioxide in open-topped containers on the sea floor. The carbon dioxide reacted with the carbonate system in the overlying seawater, and carbon dioxide-rich seawater flowed out onto the sediment. We placed inverted-funnel traps near the containers and ~75 m away from them. Measurements of pH confirmed that the area near the containers was exposed to carbon dioxide-rich seawater. As a test taxon, we chose harpacticoid copepods. The traps near the source of the carbon dioxide-rich seawater caught significantly more harpacticoids than those far from it. The harpacticoids apparently attempted to escape from the advancing front of carbon dioxide-rich seawater and therefore presumably found exposure to it to be stressful.

KEY WORDS: Global warming · CO2 sequestration · Deep sea · Benthic infauna · Harpacticoid copepods · Emergence

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