Rate Of Acidification Off US West Coast Moving At Twice The Rate Of Planetary Average
The Pacific Ocean off the West Coast is acidifying at twice the rate of the rest of the world’s oceans, according to researchers, with potentially catastrophic effects on shellfisheries.
The findings, published Monday in the journal Nature Geoscience, were the product of a seven-year study led by Emily Osborne, a researcher with the National Oceanographic and Atmospheric Administration’s ocean acidification program. Osborne began collecting samples of sediment from the Santa Barbara Basin off the coast of Southern California in 2013. Because the basin has little oxygen and a dearth of plants and animals, the ocean floor has remained relatively undisturbed. The sediment cores she pulled from the basin contained the shells of foraminifera, a single-celled plankton, dating back to 1895.
After weighing and photographing each specimen, Osborne was able to use the thickness of the shells to establish a 100-year record of pH levels in the waters of the California Current, which runs along the West Coast. She found that, since 1895, shell thickness had decreased by 20 percent due to increased ocean acidification. “I started looking at the lowest, oldest parts of core and worked my way to top,” she said. “It was crazy to see visually how the shell changed throughout the core.”
5. The graph shows the decline from 1900 to 2000 in the concentration of carbonate ions in the waters off California. Carbonate ions are the building blocks used by foraminifera and other shelled marine species to build their shells. As carbon dioxide concentrations have risen in these Pacific Ocean waters due to absorbing excess carbon dioxide emissions and upwelling of carbon dioxide-rich waters from the deep, the carbonate ion concentration has declined and acidity has increased, making it more difficult for marine species to build shells. The inset photos show (a) a typical foraminifera shell; (b) cross section of a shell from 1900 showing thickness of the shell; and (c) a shell from 2000 showing a thinner shell wall. Courtesy/Emily Osborne/NOAA
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https://www.oregonlive.com/environment/2019/12/ocean-waters-off-west-coast-acidifying-at-twice-the-rate-of-global-average-noaa-researcher-finds.html
