Ocean acidification project

Rising levels of atmospheric carbon dioxide (CO2), a major “greenhouse” gas and driven primarily through increased fossil fuel emissions and changes in land use, produce changes in ocean chemistry that may affect marine life globally. Since the Industrial Revolution (IR), the atmospheric CO2 concentration has increased by about 35%. When CO2 from the atmosphere dissolves in seawater, it reacts with water to produce carbonic acid that acidifies seawater. Carbonic acid decreases the ocean pH, hence the term “acidification”. In response, ocean pH has decreased from about 8.2 to 8.1 since IR. Ocean pH is expected to continue to decline additional 0.2 – 0.3 units by the next century.

In January 2009 PMEL, AOML, and NOAA’s Coral Health and Monitoring Program deployed the MapCO2 buoy in order to establish an Atlantic Ocean Acidification Test-bed (AOAT) in coastal coral reef environments. This mooring is located along the fore-reef of the Cayo Enrique shelf reef at La Parguera, Puerto Rico. This buoy complement the Integrated Coral Observing Network (ICON) located at Media Luna shelf reef. Local support for the mooring was initially provided by the Caribbean Coral Reef Institute; subsequently by CariCOOS and throughout the deployment by the University of Puerto Rico, Department of Marine Sciences. A suite of chemical, physical, and meteorological measurements monitored within the La Parguera Marine Reserve are used to track the dynamics and controls on local carbon chemistry at the site. These autonomous observations are validated and supplemented on a weekly basis through a discrete sampling campaign conducted by CariCOOS. For more information visit: http://www.pmel.noaa.gov/co2/story/La+Parguera

The figure shows measurements of annual seawater aragonite saturation state (Ωarg) from Enrique reef (black line) compared to the offshore Caribbean Sea estimations using OAPS model (blue line). Historical context estimates using the oceanic water values (red dashed lines) shows that during preindustrial times (PIR) the Ωarg value was approximately 4.6. After the Industrial Revolution the increase in CO2 emissions have decreased the Ωarg, in 2050 is expected to decrease around 3.4 and for the next century to 2.8. Currently, in tropical oceanic surface waters of the Caribbean, Ωarg typically ranges from 4 to 3.7, and is believed to be adequate to support robust calcification. However, these values are declining within the Caribbean region at a rate of about 3% per decade. Maximum values of Ωarg are in early spring and winter. During the summer and fall these values considerably decrease due to the “local effects”. Scientist from the University of Miami (UM), Columbia University, Woods Hole Oceanographic Institution (WHOI), the Atlantic Oceanographic and Meteorological Laboratory (AOML) and the Pacific Marine Environmental Laboratory (PMEL), in collaboration with CariCOOS expect to quantify local effects that drive down Ωarg in waters of the Marine Reserve of La Parguera. As the Caribbean waters are expected to exhibit some of the highest Ωarg values in the Tropical Atlantic throughout this century, these may become a refuge for many marine calcifiers.

More details of the Real Time MapCO2 Data in:

Pacific Marine Environmental Laboratory (PMEL)

Coral Reef Early Warning System (CREWS)

Coral Reef Watch

, December 2011. Web site.

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