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U.S. Geological Survey Data Series 535A

USGS Field Activity 08FSH01 on the West Florida Shelf, Gulf of Mexico, in August 2008

By Lisa L. Robbins,1 Paul O. Knorr,1 Xuewu Liu,2 Robert H. Byrne,2 and Ellen A. Raabe1

1U.S. Geological Survey, St. Petersburg, FL 33701.
2University of South Florida, College of Marine Science, St. Petersburg, FL 33701.

U.S. Department of the Interior
U.S. Geological Survey
St. Petersburg Coastal and Marine Science Center

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Home | Acronyms | Contents | Instrument | Methods | Data | Metadata | Trackline

Page Contents:

Information Statement

System Requirements

Project Summary


Disc Organization

Getting Started


References Cited

Study Area Map

Information Statement

This publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

System Requirements

This disc is readable on any computing platform that has standard CD driver software installed. The minimum software requirements are a Web browser, Adobe Reader, and a text editor. If you cannot fully access the information on this page, please contact USGS Information Services at or 1-888-ASK-USGS.

Project Summary

From August 11 to 15, 2008, a cruise led by the U.S. Geological Survey (USGS) collected air and sea surface partial pressure of carbon dioxide (pCO2), pH, dissolved inorganic carbon (DIC), and total alkalinity (TA) data on the west Florida shelf. Approximately 1,600 data points were collected underway over a 650-kilometer (km) trackline using the Multiparameter Inorganic Carbon Analyzer (MICA). The collection of data extended from Crystal River southward to Marco Island, Florida (~400 km), and westward up to 160 km off the Florida coast. Discrete water samples from approximately 40 locations were also taken at specific localities to corroborate underway data measurements. The USGS St. Petersburg Coastal and Marine Science Center (SPCMSC) assigns a unique identifier to each cruise or field activity. For example, 08FSH01 tells us the data were collected in 2008 for the Response of Florida Shelf (FSH) Ecosystems to Climate Change project, and the data were collected during the first field activity for that study in that calendar year.


As humans continue to burn fossil fuels, the pCO2 increases in the atmosphere, and a large portion of this anthropogenic CO2 is dissolved in the oceans (Broecker and others, 1979; Sabine and others, 2002). As a consequence, the chemistry of the ocean is changing, a phenomenon now commonly referred to as "ocean acidification." As CO2 is absorbed by surface waters, carbonic acid forms, which then titrates carbonate ions (CO32-) to reestablish chemical equilibrium. This is a problem for marine organisms that precipitate calcium carbonate to form their skeletons, tests, and shells (Kleypas and others, 1999; Kuffner and others, 2008). For example, the effects of ocean acidification on corals, which produce aragonite, are related to changes in pH and 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). Since pH and CO32- are strongly interdependent through the inorganic carbon system, the decrease in pH will cause a proportionally 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 the 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. Measuring carbonate saturation states and calcification rates in a systematic way, particularly at subtropical latitudes, where carbonate saturation states are naturally lower than in the tropics and fluctuate seasonally, will allow scientists to construct a baseline for the assessment of future changes.

As part of the 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 Coastal and Marine Geology Program project Response of Florida Shelf Ecosystems to Climate Change, data on carbonate chemistry of the ocean's surface were collected along transects on the shallow inner west Florida shelf. Through a partnership with the University of South Florida (USF), ships have been outfitted with flow-through instrumentation, specifically the Multiparameter Inorganic Carbon Analyzer (MICA) instrumentation (Wang and others, 2007) developed by Dr. Robert Byrne and engineers from SRI and the University of South Florida College of Marine Science Center for Ocean Technology (more info). The system consists of three seawater channels (surface sea water pCO2, TCO2, and pH) and an air channel (atmospheric pCO2). All measurements (four channels) are based on the same spectrophotometric principles. The system can operate continuously with a sampling frequency of every 3 minutes. For each sample, all four parameters are measured and recorded simultaneously. Conductivity, temperature, and depth (CTD) measurements were performed concurrently. Total alkalinity was sampled at discrete locations, providing another level of quality control for MICA data. These are critical parameters for calculating saturation states and thus calcification potential of marine organisms. The data collected will allow the USGS, National Oceanic and Atmospheric Administration (NOAA), and 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.

Disc Organization

This report is divided into seven sections: Acronyms and Abbreviations, Disc Contents, Instrument, Methods, 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 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.

Getting Started

To access the information contained on this disc, use a Web browser to open the file index.html.


We would like to acknowledge Stephan Meylan and Matthew Gove for their contributions in preparing this Data Series for publication.

References Cited

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, 112.

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.

Byrne, R.H., Liu, Xuewu, Kaltenbacher, E.A., and Sell, Karen, 2002, Spectrophotometric measurement of total inorganic carbon in aqueous solutions using a liquid core waveguide: Analytica Chimica Acta, v. 451, no. 2, p. 221-229.

Clayton, T.D., and Byrne, R.H., 1993, Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results: Deep-Sea Research, v. 40, no. 10, p. 2115-2129.

Dickson, A.G., 2006, Oceanic Carbon Dioxide Quality Control-Batch 76 Information: Scripps Institution of Oceanography, available online at (92 KB PDF).

Dickson, A.G., 1990, Standard potential of the reaction AgCl(s) + .5H2(g) = Ag(s) + HCl(aq) and the standard acidity constant of the ion HSO4- in synthetic sea water from 273.15 to 318.15 K: The Journal of Chemical Thermodynamics, v. 22, no. 2, p. 113-127.

Dickson, A.G., and Millero, F.J., 1987, A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media: Deep Sea Research Part A, Oceanographic Research Papers, v. 34, no. 10, p. 1733-1743.

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., available online at

Kleypas, J.A., Buddemeier, R.W., Archer, David, Gattuso, J.-P., Langdon, Chris, and Opdyke, B.N., 1999, Geochemical consequences of increased atmospheric carbon dioxide on coral reefs: Science, v. 284, no. 5411, p. 118-120.

Kuffner, I.B., Andersson, A.J., Jokiel, P.L., Rodgers, K.S., and Mackenzie, F.T., 2008, Decreased abundance of crustose coralline algae due to ocean

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.

Liu, Xuewu, Byrne, R.H., Robbins, L.L., Knorr, P.O., Lebon, Geoffrey, Alin, Simone, and Feely, R.A., 2009, Use of the MICA system for coastal CO2 research: Second North American Carbon Program All-Investigators Meeting, February 17-20, 2009, San Diego, CA.

Mehrbach, C., Culberson, C.H., Hawley, J.E., and Pytkowicz, R.M., 1973, Measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure: Limnology and Oceanography, v.18, p. 897-907.

Orr, J.C., and 25 others, 2005, Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms: Nature, v. 437, p. 681-686.

Pierrot, Denis, Lewis, E., and Wallace, D.W.R., 2006, MS Excel program developed for CO2 system calculations-ORNL/CDIAC-105a: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee. 31 p.

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.

Wang, Z.A., Liu, Xuewu, Byrne, R.H., Wanninkhof, Rik, Bernstein, R.E., Kaltenbacher, E.A., and Patten, James, 2007, Simultaneous spectrophotometric flow-through measurements of pH, carbon dioxide fugacity, and total inorganic carbon in seawater: Analytica Chimica Acta, v. 596, no. 1, p. 23-36.

Yao, Wensheng, 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.

Zhang, Huining, 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.

Home | Acronyms | Contents | Instrument | Methods | Data | Metadata | Trackline

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