Reduced calcification in modern Southern Ocean planktonic foraminifera

• Published in: Nature Geoscience
• Main Authors: Moy, AD, Howard, W, Bray, SG, Trull, T
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2009
• Subjects: Earth Sciences; Atmospheric Sciences; Climate Change Processes; Southern Ocean; Ocean acidification; Planktonic foraminifera
• Online Access: http://www.nature.com/ngeo/index.html; https://doi.org/10.1038/NGEO460; http://ecite.utas.edu.au/57655

Anthropogenic carbon dioxide has been accumulating in theoceans, lowering both the concentration of carbonate ionsand the pH (ref. 1), resulting in the acidification of seawater. Previous laboratory experiments have shown thatdecreased carbonate ion concentrations cause many marinecalcareous organisms to show reduced calcification rates25.If these results are widely applicable to ocean settings,ocean acidification could lead to ecosystem shifts. Planktonicforaminifera are single-celled calcite-secreting organisms thatrepresent between 25 and 50% of the total open-ocean marinecarbonate flux6 and influence the transport of organic carbonto the ocean interior7. Here we compare the shell weights ofthe modern foraminifer Globigerina bulloides collected fromsediment traps in the Southern Ocean with the weights ofshells preserved in the underlying Holocene-aged sediments.We find that modern shell weights are 3035% lower thanthose from the sediments, consistent with reduced calcificationtoday induced by ocean acidification. We also find a linkbetween higher atmospheric carbon dioxide and low shellweights in a 50,000-year-long record obtained froma SouthernOcean marine sediment core. It is unclear whether reducedcalcification will affect the survival of this and other species,but a decline in the abundance of foraminifera caused byacidification could affect both marine ecosystems and theoceanic uptake of atmospheric carbon dioxide.