U.S. Geological Survey Data Series 712
1U.S. Geological Survey, St. Petersburg, FL 33701.
2University of South Florida, College of Marine Science, St. Petersburg, FL 33701
3Jacobs Technology, St. Petersburg, FL, 33701
U.S. Department of the
U.S. Geological Survey
St. Petersburg Coastal and Marine Science Center
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As humans continue to burn fossil fuels, the partial pressure of carbon dioxide (pCO2) increases in the atmosphere and a large portion of this anthropogenic CO2 is absorbed by the oceans (Broecker and others, 1979; Sabine and others, 2002). As CO2 is absorbed by surface waters, it forms carbonic acid, which then titrates carbonate ions (CO32-) to reestablish chemical equilibrium. As a consequence, the chemistry of the ocean is changing, a phenomenon now commonly referred to as “ocean acidification.” This is a problem for marine organisms that precipitate calcium carbonate to form their skeletons, tests, and shells (Kleypas and others, 1999). For example, the effects of ocean acidification on corals, which produce aragonite, are not directly related to changes in pH, but are instead related to corresponding changes in aragonite saturation state (Ωa), where Ωa is the ratio of the ion concentration product (Ca2+ x CO32-) to the stoichiometric aragonite solubility product (K*sp); (Langdon and Atkinson, 2005). Because pH and CO32- are strongly interdependent through the inorganic carbon system, the decrease in pH will cause a proportionally much greater decrease in CO32-. Experimental work has demonstrated decreases in calcification rates of corals, coralline algae, foraminifera, and other calcifying organisms in waters that are still supersaturated with respect to calcium carbonate minerals (Langdon and Atkinson, 2005; Orr and others, 2005). New research has recently confirmed that carbonate mineral saturation state has measurably decreased over the past two decades in the North Atlantic gyre (Bates, 2007). If the experimental data are directly applicable to the field, measurable decreases in calcification rates of important reef-building organisms should already be visible. It is critical to start measuring carbonate saturation state and calcification rates in a systematic way now, including subtropical latitudes where carbonate saturation states are already naturally low and fluctuate seasonally, in order to construct a baseline for the assessment of future changes.
As part of the U.S. Geological Survey USGS Climate Change project “Monitoring and modeling of Florida Shelf carbonate saturation state and calcification rates: setting a baseline for response of ocean acidification on marine habitats” and the USGS Coastal and Marine Geology Program project "Response of Florida Shelf Ecosystems to Climate Change" (Principal Investigator, Dr. Lisa Robbins), data on surface seawater (SW) carbonate chemistry were collected along transects on the shallow inner west Florida shelf. The data collected will allow the USGS, National Oceanic and Atmospheric Administration (NOAA), and University of South Florida (USF) to map variations in ocean chemistry including carbonate saturation states along designated tracks. The USGS is also partnering with NOAA and the National Aeronautics and Space Administration (NASA) for the modeling of saturation state data.
During May and June 2011 the (USGS), in cooperation with (USF), conducted geochemical surveys on the west Florida Shelf to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. The first cruise was conducted from May 3 to 9 (11BHM01) and the second was from June 25 to 30 (11BHM02). To view each cruise's survey lines, please see the Trackline page. Each cruise took place aboard the Research Vessel (R/V) Weatherbird II, a ship of opportunity led by Dr. Kendra Daly (USF), which departed from and returned to Saint Petersburg, Florida.
Data collection included sampling of the surface and water column with lab analysis of pH, dissolved inorganic carbon (DIC) or total carbon dioxide (TCO2), and total alkalinity (TA). lLb analysis was augmented with a continuous flow-through system (referred to as sonde data) with a conductivity-temperature-depth (CTD) sensor, which also recorded salinity and pH. Corroborating the USGS data are the vertical CTD profiles (referred to as station samples) collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence and optical backscatter. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts. Two autonomous flow-through (AFT) instruments recorded pH and CO2 every 3-5 minutes on each cruise (referred to as AFT data).
This report is divided into six sections: Acronyms and Abbreviations, Disc Contents, Methods, Cruise Data, Federal Geographic Data Committee (FGDC) Metadata, and Trackline. Links at the top and bottom of each page provide access to these sections. This report contains links to information from the USGS, collaborators, and other available resources if access to the Internet is available while viewing these documents. Geographic information system (GIS) files, HyperText Markup Language (HTML) files, and images used to produce the Web pages are also included in this report. The Disc Contents page contains a listing with locations and links to all files and folders contained on this disc.
To access the information contained on this disc, use a Web browser to open the file index.html.
Bates, N.R., 2007, Interannual variability of the oceanic CO2 sink in the subtropical gyre of the North Atlantic Ocean over the last 2 decades: Journal of Geophysical Research, v.112, 26 p, doi:10.1029/2006JC003759.
Broecker, W.S., Takahashi, T., Simpson, H.J., and Peng, T.H., 1979, Fate of fossil fuel carbon dioxide and the global carbon budget: Science, v. 206, no. 4417, p. 409-418.
Dickson, A.G., Sabine, C.L., and Christian, J.R., eds., 2007, Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 p, accessed November 25, 2013 at http://cdiac.ornl.gov/oceans/Handbook_2007.html.
Kleypas, J.A., Feely, R.A., Fabry, V.J., Langdon, C., Sabine, C.L., and Robbins, L.L., 2006, Impacts of ocean acidification on coral reefs and other marine calcifiers—A guide for future research: Report of a workshop held 18–20 April, 2005, St. Petersburg, FL, sponsored by the National Science Foundation, the National Oceanic and Atmospheric Administration, and the United States Geological Survey, p. 88.
Langdon, C., and Atkinson, M.J., 2005, Effect of elevated pCO2 on photosynthesis and calcification of corals and interactions with seasonal change in temperature/irradiance and nutrient enrichment: Journal of Geophysical Research, v. 110, 16 p, doi:10.10/2004JC002576.
Liu, Xuewu, Patsavas, M.C., and Byrne, R.H., 2011, Purification and characterization of meta-cresol purple for spectrophotometric seawater pH measurements: Environmental Science and Technology, v. 45, p. 4862–4868.
Orr, J.C., and others, 2005, Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms: Nature, v. 437, p. 681-686, doi:10.1038/nature04095.
Sabine, C.L. Feely, R.A., Key, R.M., Bullister, J.L., Millero, F.J., Lee, K., Peng, T.-H., Tilbrook, B., Ono, T., and Wong, C.S., 2002, Distribution of anthropogenic CO2 in the Pacific Ocean: Biogeochemical Cycles, v. 16, no. 4, p. 1083, doi:10.1029/2001GB001639.
Yao, W., and Byrne, R.H., 1998, Simplified seawater alkalinity analysis: Use of linear array spectrometers: Deep-Sea Research Part I, v. 45, no. 8, p. 1383-1392, doi: 10.1016/S0967.
Zhang, H., and Byrne, R.H., 1996, Spectrophotometric pH measurements of surface seawater at in-situ conditions: Absorbance and protonation behavior of thymol blue: Marine Chemistry, v. 52, no. 1, p. 17-25, doi:10.1016/0304-4203(95)00076-3.
Robbins, L.L., Knorr, P.O., Daly, K.L., Taylor, C.A., Barrera, K.E. 2014, USGS Field Activities 11BHM01 and 11BHM02 on the West Florida Shelf, Gulf of Mexico, May and June 2011: U.S. Geological Survey Data Series 712, 7 p., https://dx.doi.org/10.3133/ds712.
ISSN 2327-638X (online)