Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports

Dennis A Hansell, Hugh W. Ducklow, Alison M. Macdonald, Molly O Neil Baringer

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Recently there has been discussion about the metabolic state of the ocean, with arguments questioning whether the open ocean is net autotrophic or net heterotrophic. Accurately determining the metabolic balance of a marine system depends on fully defining the system being evaluated and on quantifying the inputs and outputs to that system. Here, a net northward transport of dissolved organic carbon (DOC) (across 24.5°N) of 3.3 ± 1.9 Tmol C yr -1 was determined using basin-wide transport estimates of DOC. This flux, coupled with DOC inputs from the Arctic Ocean (2.2 ± 0.8 Tmol C yr-1), the atmosphere (0.6 ± 0.08 Tmol C yr-1), and rivers (3.1 ± 0.6 Tmol C yr-1), indicates net heterotrophy in the North Atlantic (full depth, 24.5-72°N) of 9.2 ± 2.2 Tmol C yr-1. This rate is small (<2%) compared to autochthonous production (∼494 Tmol C yr-1) and consumption (production:respiration of 0.98), indicating that the North Atlantic is essentially metabolically balanced and that autochthonous production is remineralized within the basin. The upper layer of the subtropical gyre has previously been reported to exhibit high rates of net heterotrophy, but our analysis does not support those findings. Instead, allochthonous inputs of organic carbon to the upper subtropical gyre are an order of magnitude less than required by the elevated rates of net heterotrophy reported. We find, too, that net mineralization of allochthonous DOC within the basin could account for 10% of the preindustrial inorganic carbon exported from the basin to the south. Two factors, the import of organic matter and the unique thermohaline circulation pattern of the North Atlantic, are primary in ensuring net heterotrophy in the basin.

Original languageEnglish (US)
Pages (from-to)1084-1094
Number of pages11
JournalLimnology and Oceanography
Volume49
Issue number4 I
StatePublished - Jul 2004

Fingerprint

heterotrophy
Atlantic Ocean
dissolved organic carbon
organic matter
basins
basin
gyre
oceans
thermohaline circulation
carbon
inorganic carbon
open ocean
imports
import
Arctic region
mineralization
respiration
organic carbon
North Atlantic Ocean
rivers

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

Cite this

Hansell, D. A., Ducklow, H. W., Macdonald, A. M., & Baringer, M. O. N. (2004). Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports. Limnology and Oceanography, 49(4 I), 1084-1094.

Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports. / Hansell, Dennis A; Ducklow, Hugh W.; Macdonald, Alison M.; Baringer, Molly O Neil.

In: Limnology and Oceanography, Vol. 49, No. 4 I, 07.2004, p. 1084-1094.

Research output: Contribution to journalArticle

Hansell, DA, Ducklow, HW, Macdonald, AM & Baringer, MON 2004, 'Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports', Limnology and Oceanography, vol. 49, no. 4 I, pp. 1084-1094.
Hansell, Dennis A ; Ducklow, Hugh W. ; Macdonald, Alison M. ; Baringer, Molly O Neil. / Metabolic poise in the North Atlantic Ocean diagnosed from organic matter transports. In: Limnology and Oceanography. 2004 ; Vol. 49, No. 4 I. pp. 1084-1094.
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