Ocean Acidification: Research on Top of the World
The oceans currently absorb approximately one-third of total emissions of carbon dioxide (CO2) generated by fossil-fuel combustion. As CO2 is absorbed by the ocean, it forms carbonic acid and lowers the slightly alkaline (basic) pH of seawater. This suite of chemical changes is known collectively as ocean acidification. Lowered ocean pH alters the ability of many calcifying marine organisms to produce calcium carbonate skeletons and shells. Ocean acidification is an emerging global problem because, as CO2 emissions continue, so will the lowering of ocean pH that may cause profound changes in marine food webs and global ecosystems. (See related Sound Waves articles "Impacts of Ocean Acidification on Coral Growth: Historical Perspectives from Core-Based Studies," "Research Cruises Collect Measurements on the West Florida Shelf for Modeling Climate Change and Ocean Acidification," and "Coral-Reef Builders Vulnerable to Ocean Acidification.")
The U.S. Geological Survey (USGS), along with other federal agencies, is working with the international scientific community to help standardize and compile information that adequately describes ocean chemistry trends and analyzes relations between these trends and carbon sources, cycles, and human activities. The USGS has been pioneering work to improve capabilities in measuring marine carbonate species and metabolic cycles that affect carbon compounds (http://coastal.er.usgs.gov/flash/), as well as characterizing CO2 concentrations in a wide variety of marine environments (http://coastal.er.usgs.gov/crest/).
As part of that effort, USGS scientists are participating in a unique opportunity to sample the remote waters of the Arctic Ocean during the 2010 U.S.-Canada Extended Continental Shelf Survey research expedition on board the U.S. Coast Guard vessel Healy from August 2 to September 6, 2010. (See related article "Scientists Set Sail to Map the Arctic Seafloor," this issue.) By collecting CO2 data and related chemical samples in the largely uncharted Arctic waters, scientists will fill important gaps of knowledge that will contribute to better understanding of the impacts of CO2 on ocean chemistry, trends in ocean acidification, and implications for climate change. "Models suggest that the Arctic is already undersaturated with respect to carbonate minerals during part of the year," said Lisa Robbins, USGS oceanographer. "Our data will provide important baseline information about this region that looks at marine carbonate chemistry; saturation states, dissolution potential and the role microbial communities play in carbon cycling."
"Shiptime research is very expensive, so ‘piggy-backing' science missions is always a good idea if it can be arranged to the benefit of all parties," said Robbins. Working together in the Arctic region and collecting such robust datasets will likely serve multiple uses and lines of research. "When scientists coordinate science activities in close proximity to one another, it creates a rich environment for dialogue and exchange. As we work together, ideas are cross-pollinated and everyone involved develops improved understanding. These are the kind of synergistic benefits that will take place during this research cruise," said Robbins. It is likely that these benefits will continue to be realized long after the data have been collected.
A highly specialized, collaborative team has been assembled for the Arctic cruise and includes USGS senior scientists Lisa Robbins and Kim Yates, and University of South Florida's (USF) College of Marine Science Professor Bob Byrne, along with technicians Chris Dufore (USGS), and Mark Patsavas (USF), and research associate Xuewu Liu (USF). During the cruise, discrete water samples will be collected along track lines and through the water column. They will be analyzed both on board the Healy and back in the USGS laboratory in St. Petersburg, Florida. Additionally, state-of-the-art equipment pioneered by Byrne's laboratory will provide "flow-through" data on the concentrations of total carbon and carbon dioxide in seawater, measured as the partial pressure expressed as pCO2, since it is in gas form. The system will also measure pH using highly precise spectrophotometric methods. For the first time, in-place measurement of carbonate ion concentrations will be attempted. Bacterial community samples will also be collected, along with nutrients, dissolved organic carbon, and oxygen and carbon isotope samples. USGS microbiologist John Lisle will analyze microbial samples. The team has been working for months preparing analytical and sampling equipment for the extended time at sea.
The USGS ocean acidification team–Lisa Robbins, Kim Yates, and Chris Dufore–participated in a high profile, first-of-its-kind, National Science Foundation (NSF)-sponsored short course on ocean acidification in November 2009 at Woods Hole Oceanographic Institution. Yates and Dufore demonstrated and taught spectrophotometric pH and alkalinity techniques, experimental techniques, and data analysis methods. Robbins, an invited member of the organizing committee for this unique short course, worked with the other members to develop the course content and agenda. Yates was chosen as one of 20 international expert scientists to lecture on specific topics in ocean acidification. Yates discussed manipulation of carbonate system parameters in ocean acidification experiments. The state-of-the-art analytical methods that she and Dufore demonstrated are used in the USGS laboratory in St. Petersburg, Florida.
This dataset will fill knowledge gaps in the global map of ocean carbon species and will be shared with the international scientific community. For more than 10 years, the USGS team has been working to characterize carbon species found in different marine environments. "We have detailed information from tropical waters, temperate waters, and open ocean as well as continental shelves. The data from the Arctic Ocean will give us the ability to compare trends from the equator to those observed at the Earth's poles," said Kim Yates, research oceanographer.
Understanding climate change in the Arctic, including ocean acidification, is of high priority to the U.S. Department of the Interior's Secretary Salazar. Potential impacts from observed trends will have broad global influence affecting the seafood industry, coral reef health, sedimentation patterns, carbon management policies and related economic impacts, as well as future climate. USGS science is critical for making informed policy decisions and in developing strategies to address ocean acidification with the global community.
Robbins participates on the Interagency Working Group on Ocean Acidification (IWG-OA). The IWG-OA was formed as a result of the Federal Ocean Acidification Research and Monitoring (FOARAM) Act of 2009, which calls for an interagency working group (IWG) under the Joint Subcommittee on Ocean Science and Technology (JSOST) to develop a strategic research plan and to coordinate Federal ocean acidification activities. This Act also calls for the establishment of a Federal ocean acidification program. An initial report from the IWG-OA was sent to Congress in March 2010, and the Strategic Plan is currently being written, with intent to deliver it to Congress in 2011.
The USGS also participates in the Arctic Mapping and Assessment Program, part of the Nordic Council. Robbins and Yates worked with other scientists to co-author an Arctic Ocean Acidification Scoping paper. Robbins presented the Scoping paper to the Arctic Monitoring and Assessment Program (AMAP) in February 2010.
The data from this research cruise will be shared with AMAP and the rest of the global scientific community. They will help expand knowledge and capabilities of scientists worldwide to understand future ocean and climate trends and impacts.
Follow the research team on the Healy at the Extended Continental Shelf Project Web site.
For more information on interagency science bodies and committees addressing the ocean acidification problem, see Ocean Carbon and Biogeochemistry and the Interagency Working Group on Ocean Partnerships (IWG-OP).
in this issue:
Ocean Acidification: Research on Top of the World