Acidifying oceans will cause a diversity and survival crisis for microscopic marine organisms, finds research

Oceanic responses to climate and human interactions have been studied for decades. In recent years the effects of increasing ocean acidity have been featured, with stark images of coral reefs being decimated by bleaching.

Acidification results from ocean-atmosphere interactions, whereby carbon dioxide from the atmosphere is drawn down, reacting with water molecules to form carbonic acid. This then further breaks down into hydrogen ions and bicarbonate ions, with the former causing a reduction in pH.

Corals are not the only marine organisms to be made up of calcium carbonate and therefore susceptible to ocean acidification however. Single-celled organisms known as foraminifera produce chambered shells of calcium carbonate, and they are an important part of marine food chains, being primary and secondary consumers. Most tend to be benthic, where they live in or at the seafloor, but a smaller proportion are planktonic, living within the water column.

New research, published in Geoscience Frontiers, has focused on the impact of acidification on benthic foraminifera living on the continental shelf of the West Pacific Ocean. Researchers at the Institute of Oceanology in the Chinese Academy of Sciences conducted experiments for eight months on foraminifera cultures taken from four sites in the Yellow Sea, involving 4,626 specimens attributed to 39 species. They tested foraminifera response to marine conditions when progressively more carbon dioxide (400ppm, 800ppm, 1200ppm and 1600ppm) was fed into the system. This reflects modeling scenarios reported by the Intergovernmental Panel on Climate Change (IPCC) where worse-case scenario simulations are based upon carbon dioxide concentrations of 1,600 ppm and above.

[You can read the original research article published on the OA-ICC News Stream here.]

Hannah Bird,, 13 July 2023. Press release.

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