Threatened species drive the strength of the carbonate pump in the northern Scotia Sea

• Published in: Nature communications 2018-11, Vol.9 (1), p.4592-7, Article 4592
• Main Authors: Manno, C., Giglio, F., Stowasser, G., Fielding, S., Enderlein, P., Tarling, G. A.
• Format: Article
• Language: English
• Subjects: 631/45/47/4113; 704/47/4113; 704/829; Abundance; Acidification; Calcification; Carbon - analysis; Carbon dioxide; Carbon sequestration; Carbonates - analysis; Communities; Drawdown; Endangered & extinct species; Endangered Species; Humanities and Social Sciences; multidisciplinary; Oceans and Seas; Organic carbon; Organic Chemicals - analysis; Particulate Matter - analysis; Plankton; Plankton - metabolism; Polar environments; Predation; Science; Science (multidisciplinary); Seasons; Threatened species
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07088-y

The efficiency of deep-ocean CO 2 sequestration is regulated by the relative balance between inorganic and organic carbon export respectively acting through the biological carbon pump (BCP) and the carbonate counter pump (CCP). The composition and abundance of calcifying species in the prevailing oceanic plankton community plays a major role in driving the CCP. Here we assess the role of these calcifying organisms in regulating the strength of the CCP in a Southern Ocean region (northern Scotia Sea) known to be a major hotspot for the drawdown of atmospheric CO 2 . We show that, when shelled pteropods dominate the calcifying community, the total annual reduction of CO 2 transferred to the deep ocean doubles (17%) compared to when other plankton calcifiers dominate (3–9%). Furthermore, predation enhances their contribution through the removal of organic soft tissue. Pteropods are threatened in polar regions by ocean warming and acidification. We determine that their potential decline would have major implications to the comparative strengths of the BCP and CCP. The Scotia Sea, located in the Southern Ocean, is a major hotspot for the drawdown of atmospheric CO 2 . Here, the authors show that the strength of the carbonate counter pump doubles when shelled pteropods dominate the plankton calcifier community, counteracting the amount of CO 2 transferred to the deep ocean.