Deep-sea Field Experiments on the Biological Impacts of Direct Deepsea CO2 Injection

Direct injection of CO2 into the ocean, a radical idea suggested 25 years ago (Marchetti 1977), is among several carbon sequestration alternatives under consideration to offset the accelerating rise in anthropogenic greenhouse gases (Reichle et al 1999, Brewer et al. 1999). This issue raises important questions concerning the impacts of pH changes and elevated CO2 levels for marine ecosystems and the role, if any, ocean sequestration should play in a national or global carbon management strategy. While there is uncertainty concerning physical responses to greenhouse gas forcing (Caldeira et al 2003), there is no doubt that oceanic CO2 levels have risen significantly (Keeling and Whorf 2002, Barnola et al. 2003) and will continue to do so (Marland et al. 2001). Roughly 1/3rd of current fossil fuel CO2 emissions (~7 GtCO2y -1) enter the sea surface through air-sea exchange (Houghton et al. 1990, McNeil et al 2003), thereby acidifying the upper ocean (Sabine et al. 2002). Continued acidification by air/sea CO2 exchange (Haugan and Drange 1992) or direct ocean CO2 sequestration (Drange et al. 2001, Harvey 2003) will challenge the physiological tolerances of species inhabiting both shallow (Kleypas et al. 1999, Knowlton 2001) and deep (Tamburri et al. 2000, Seibel and Walsh 2003) marine ecosystems. Here we present the initial results of in situ deep-sea CO2 release experiments off Central California, showing that various deep-sea taxa are sensitive to short-term (~ 1 mo.) exposure to CO2-rich, low pH plumes emanating from deep-sea CO2 pools