Remineralization of particulate organic carbon in an ocean oxygen minimum zone

• Published in: Nature communications 2017-03, Vol.8 (1), p.14847-14847, Article 14847
• Main Authors: Cavan, E. L., Trimmer, M., Shelley, F., Sanders, R.
• Format: Article
• Language: English
• Subjects: 704/106/829/827; 704/47/4113; 704/829/826; Carbon sequestration; Humanities and Social Sciences; multidisciplinary; Oceanography; Plankton; Respiration; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms14847

Biological oceanic processes, principally the surface production, sinking and interior remineralization of organic particles, keep atmospheric CO 2 lower than if the ocean was abiotic. The remineralization length scale (RLS, the vertical distance over which organic particle flux declines by 63%, affected by particle respiration, fragmentation and sinking rates) controls the size of this effect and is anomalously high in oxygen minimum zones (OMZ). Here we show in the Eastern Tropical North Pacific OMZ 70% of POC remineralization is due to microbial respiration, indicating that the high RLS is the result of lower particle fragmentation by zooplankton, likely due to the almost complete absence of zooplankton particle interactions in OMZ waters. Hence, the sensitivity of zooplankton to ocean oxygen concentrations can have direct implications for atmospheric carbon sequestration. Future expansion of OMZs is likely to increase biological ocean carbon storage and act as a negative feedback on climate change. The downward transfer of organic carbon from the surface to the deep ocean is increased in oxygen minimum zones relative to oxic waters. Here, the authors show reduced interactions of zooplankton with sinking particles owing to low oxygen are likely the primary reason for the observed high transfer of carbon.