Ocean acidification likely hampers tiny shell builders in Southern Ocean



Shell-shocked: Ocean acidification likely hampers tiny shell builders in Southern Ocean

Posted: 25 Mar 2015 10:51 AM PDT

A ubiquitous type of phytoplankton — tiny organisms that are the base of the marine food web — appears to be suffering from the effects of ocean acidification caused by climate change.
According to authors of a new study, the single-celled organism under study is a type of “calcifying” plankton called a coccolithophore, which makes energy from sunlight and builds microscopic calcium carbonate shells, or plates, to produce a chalky suit of armor….
The coccolithophore E. huxleyi is important in the marine carbon cycle and is responsible for nearly half of all calcium carbonate production in the ocean, said lead study author Natalie Freeman, a doctoral student in the CU-Boulder’s Department of Atmospheric and Oceanic Sciences (ATOC). The new study indicates there has been a 24 percent decline in the amount of calcium carbonate produced in large areas of the Southern Ocean over the past 17 years. NOAA scientists have estimated that global oceans have become up to 30 percent more acidic since the Industrial Revolution. “While we generally expect acidification to negatively impact coccolithophore calcification and growth, other environmental stressors such as warming may have influenced these processes,” said Lovenduski. The two researchers, who also are affiliated with CU-Boulder’s Institute of Arctic and Alpine Research, used data collected by the SeaWiFS and MODIS satellite instruments. “These results suggest that large-scale shifts in the ocean carbon cycle are already occurring and highlight organism and marine ecosystem vulnerability in a changing climate,” wrote the CU-Boulder researchers in GRL.


Natalie M. Freeman, Nicole S. Lovenduski. Decreased calcification in the Southern Ocean over the satellite record. Geophysical Research Letters, 2015; DOI: 10.1002/2014GL062769

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