Jelly biomass sinking speed reveals a fast carbon export mechanism

• Published in: Limnology and Oceanography
• Main Authors: Lebrato, Mario, Mendes, Pedro, Steinberg, Deborah K., Cartes, Joan Enric, Jones, Bethan, Birsa, Laura M., Benavides, Roberto, Oschlies, Andreas
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Society of Limnology and Oceanography 2013
• Subjects: National Science Foundation Office of Polar Programs; Ocean acidification
• Online Access: http://hdl.handle.net/10261/93861; https://doi.org/10.4319/lo.2013.58.3.1113

10 pages, 4 figures, 3 tables Sinking of gelatinous zooplankton biomass is an important component of the biological pump removing carbon from the upper ocean. The export efficiency, e.g., how much biomass reaches the ocean interior sequestering carbon, is poorly known because of the absence of reliable sinking speed data. We measured sinking rates of gelatinous particulate organic matter (jelly-POM) from different species of scyphozoans, ctenophores, thaliaceans, and pteropods, both in the field and in the laboratory in vertical columns filled with seawater using high-quality video. Using these data, we determined taxon-specific jelly-POM export efficiencies using equations that integrate biomass decay rate, seawater temperature, and sinking speed. Two depth scenarios in several environments were considered, with jelly-POM sinking from 200 and 600 m in temperate, tropical, and polar regions. Jelly-POM sank on average between 850 and 1500 m d−1 (salps: 800–1200 m d−1; ctenophores: 1200–1500 m d−1; scyphozoans: 1000–1100 m d−1; pyrosomes: 1300 m d−1). High latitudes represent a fast-sinking and low-remineralization corridor, regardless of species. In tropical and temperate regions, significant decomposition takes place above 1500 m unless jelly-POM sinks below the permanent thermocline. Sinking jelly-POM sequesters carbon to the deep ocean faster than anticipated, and should be incorporated into biogeochemical and modeling studies to provide more realistic quantification of export via the biological carbon pump worldwide We acknowledge funding from the ‘‘European Project on Ocean Acidification’’ (EPOCA), part of the European Community’s Seventh Framework Programme (FP7/2007–2013) (grant 211384), the Kiel Cluster of Excellence ‘‘The Future Ocean’’ (D1067/87), the German project Biological Impacts of Ocean Acidification (BIOACID), funded by the Federal Ministry of Education and Research (BMBF, FKZ 03F0608B), and the U.S. National Science Foundation Office of Polar Programs (grant OPP-0823101) Peer Reviewed