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| Titel |
Short term summer to autumn variability of dissolved lipid classes in the Ligurian sea (NW Mediterranean) |
| VerfasserIn |
M. Goutx, C. Guigue, D. D. Aritio, J. F. Ghiglione, M. Pujo-Pay, V. Raybaud, M. Duflos, L. Prieur |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-21), S.1229-1246 |
| Datensatznummer |
250003911
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| Publikation (Nr.) |
 copernicus.org/bg-6-1229-2009.pdf |
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| Zusammenfassung |
| Changes in concentration and composition of Iatroscan-measured dissolved
lipids were examined at a daily to month scale, in relation to the
hydrological and biological context at a central site of the Ligurian sea,
NW Mediterranean during the PECHE-DYNAPROC 2 experiment (14 September to 17 October 2004). Lipid concentrations (excluding hydrocarbons) (TLd-HC) and
TLd-HC to DOC ratios in the 0–1000 m water column, varied from 5.3 to 48.5 μg l−1 and 0.01 to 0.09, respectively. The highest TLd-HC
concentration values were found in the 0–50 m surface layer, coinciding with
phytoplankton biomass. Significant correlations (p<0.01, n=87) between
glycolipids from chloroplast membranes, namely the
monogalactosyldiacylglycerols, a major component of dissolved lipids
(25.1±10.8% of TLd-HC, n=166), and various phytoplankton pigments
(chlorophyll cs-170, violaxanthin, diadinoxanthin, zeaxanthin, and lutein),
suggested that picoeucaryote phytoplankton were a major source of dissolved
lipids. Lipid metabolites (free fatty acids, alcohols, diacylglycerols and
monoacylglycerols), an other important component of TLd-HC (37.6±11.1%, n=166), showed a greater degree of degradation of lipids in this
transitional period than previously observed earlier in the year.
Zooplankton wax and steryl ester biomarkers (WSE) and triacylglycerols
showed a distinct periodicity in the mesopelagic layer throughout the period
investigated. Concentrations of WSE (5.5–13.6 μg/l) increased in the
0–150 m surface layer, mid-way through the cruise (4–6 October), before the
winter mixing. WSE were observed later and deeper in the mesopelagic layer
(6–11 October), accompanied by rebounds in hydrocarbons (6–8 October)
and phospholipid concentrations (12 October) in the 400–1000 m depth
layer. Zooplankton migration and/or fecal pellet egestion, followed by DOM
release from POM, were likely responsible for the appearance of these lipid
signatures in the mesopelagic layer. Because we observed these signatures
during low wind period only (<15 knots: 28 September–12 October), it may indicate that this organic matter transfer to depth was
related to undisturbed trophic web in the water column above. The low
salinity water lenses that appeared twice during the cruise in the 40–80 m
surface layer had little effect on dissolved lipid concentrations. Lower
concentrations in phosphoglycerides and hydrocarbons (HC) than in nearby sea
water suggested different microbial assemblages and different level of HC
contamination in this low salinity water. |
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