Contribution of combined carbohydrates to dissolved and particulate organic carbon after the spring bloom in the northern Bay of Biscay (North-Eastern Atlantic Ocean)

Engel, Anja, Harlay, Jérôme, Piontek, Judith and Chou, Lei (2012) Contribution of combined carbohydrates to dissolved and particulate organic carbon after the spring bloom in the northern Bay of Biscay (North-Eastern Atlantic Ocean) Continental Shelf Research, 45 . pp. 42-53. DOI 10.1016/j.csr.2012.05.016.

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Abstract

Two cruises were conducted after the diatom spring bloom in the northern Bay of Biscay (2006, 2007), to assess the contribution of combined carbohydrates to organic carbon partitioning. Partitioning of total organic carbon (TOC) into particulate organic carbon (POC) and dissolved organic carbon (DOC) differed between the two years, particularly for depths above 60 m, and was related to the vernal development of the system: a post spring-bloom system in 2007, and a more stratified summer system with higher coccolithophore abundance in 2006. In general, contribution of POC to TOC ranged between 4% and 28% and decreased with depth. Concentration of high-molecular-weight (HMW;>1 kDa) dissolved combined carbohydrates (dCCHO) ranged from 0.6 to 1.4 μmol L−1 and contributed between 4% and 11% to DOC. Concentration of particulate combined carbohydrates (pCCHO) varied between 0.03 and 1.3 μmol L−1. A high contribution of pCCHO to POC was observed in 2007, i.e. 22–60% C compared to 3–10% C in 2006, and coincided with a higher abundance of transparent exopolymer particles (TEP). TEP accounted for 0.4–2.0 μmol C L−1 in 2007 and 0.5–1.5 μmol C L−1 in 2006. Above 60 m, differences in contribution of TEP-C to POC were most pronounced yielding 15.4±3.0% in 2007 compared to relatively low 4.8±1.4%, in 2006. TEP-C could explain about 60% in 2007 and about 40% of pCCHO-C in 2006. Hence, TEP were identified as a substantial component of pCCHO and POC, particularly in the wake of the spring bloom. Molecular composition of CCHO, i.e. HMW−dCCHO+pCCHO, revealed little difference between the years but strong variation over depth. Uronic acids (URA) were identified as a major component of CCHO (20–40%). Our study indicates that the distribution and composition of CCHO in surface seawater are determined by biogeochemical processes on a seasonal scale. A better knowledge of CCHO cycling and molecular signature has therefore a high potential for a better tracing of carbon dynamics in shelf sea ecosystems.
Highlights:
► Role of combined carbohydrates for DOC–POC partitioning assessed (Bay of Biscay). ► TEP comprised substantial carbon fraction of particulate carbohydrates. ► Molecular composition of polysaccharides revealed organic matter diagenesis. ► Uronic acids comprised 20–40% of total and dissolved combined carbohydrates.

Document Type: Article
Additional Information: WOS:000308899500005
Keywords: Bay of Biscay; DOC; POC; Combined carbohydrates; TEP; Carbon partitioning; TRANSPARENT EXOPOLYMER PARTICLES; NEUTRAL SUGARS POLYSACCHARIDES; MARINE-PHYTOPLANKTON; AQUATIC ECOSYSTEMS; SIZE DISTRIBUTION; ALCIAN BLUE; MATTER; SEA; SEAWATER; TEP
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
AWI
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Refereed: Yes
DOI etc.: 10.1016/j.csr.2012.05.016
ISSN: 0278-4343
Projects: PEACE, CARBOOCEAN, Future Ocean
Date Deposited: 30 Aug 2012 12:05
Last Modified: 12 Dec 2017 10:34
URI: http://eprints.uni-kiel.de/id/eprint/15115

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