Export of submicron particulate organic matter to mesopelagic depth in an oligotrophic gyre

TitleExport of submicron particulate organic matter to mesopelagic depth in an oligotrophic gyre
Publication TypeJournal Article
Year of Publication2013
AuthorsClose H.G, Shah S.R, Ingalls A.E, Diefendorf A.F, Brodie E.L, Hansman R.L, Freeman K.H, Aluwihare LI, Pearson A.
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Pagination12565-12570
Date Published2013/07
Type of ArticleArticle
ISBN Number0027-8424
Accession NumberWOS:000322441500029
Keywordsbiogeochemistry; biomarkers; carbon export; Carbon isotopes; catalyzed reporter deposition; equatorial pacific; hybridization; in-situ; lipid biomarkers; microbial food-web; oceanography; oceans twilight zone; pacific subtropical gyre; small phytoplankton; time-series
Abstract

Sixty percent of the world ocean by area is contained in oligotrophic gyres [Longhurst A (1995) Prog Oceanog 36:77-16], the biomass of which is dominated by picophytoplankton, including cyanobacteria and picoeukaryotic algae, as well as picoheterotrophs. Despite their recognized importance in carbon cycling in the surface ocean, the role of small cells and their detrital remains in the transfer of particulate organic matter (POM) to the deep ocean remains disputed. Because oligotrophic marine conditions are projected to expand under current climate trends, a better understanding of the role of small particles in the global carbon cycle is a timely goal. Here we use the lipid profiles, radiocarbon, and stable carbon isotopic signatures of lipids from the North Pacific Subtropical Gyre to show that in the surface ocean, lipids from submicron POM (here called extra-small POM) are distinct from larger classes of suspended POM. Remarkably, this distinct extra-small POM signature dominates the total lipids collected at mesopelagic depth, suggesting that the lipid component of mesopelagic POM primarily contains the exported remains of small particles. Transfer of submicron material to mesopelagic depths in this location is consistent with model results that claim the biological origin of exported carbon should be proportional to the distribution of cell types in the surface community, irrespective of cell size [Richardson TL, Jackson GA (2007) Science 315:838-840]. Our data suggest that the submicron component of exported POM is an important contributor to the global biological pump, especially in oligotrophic waters.

DOI10.1073/pnas.1217514110
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Student Publication: 
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