BRIEF RESEARCH REPORT article
Front. Mar. Sci.
Sec. Marine Ecosystem Ecology
This article is part of the Research TopicEnvironmental and Biotic Drivers of Algae Distribution, Algae-Bacteria Interactions, and Algae Blooms in Marine EnvironmentsView all articles
Variations in carbon isotopic composition of fatty acids in Arctic pelagic particulate organic matter: A preliminary assessment over a latitudinal gradient
Provisionally accepted
Doreen Kohlbach1,2*
Benoit Lebreton3,4*
Gaёl Guillou3
Anette Wold2
Haakon Hop2
Martin Graeve1
Philipp Assmy2- 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven, Germany
- 2Norsk Polarinstitutt, Tromsø, Norway
- 3La Rochelle Universite, La Rochelle, France
- 4Hanse-Wissenschaftskolleg, Delmenhorst, Germany
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Studies of Arctic food-web structure and function by means of carbon isotopic composition (δ13C) of fatty acids (FAs) have a main challenge of identifying a proper baseline for pelagic particulate organic matter (PPOM). To assess variations in δ13C values of the FAs 16:1(n-7), 20:5(n-3) and 22:6(n-3) in PPOM, seawater was collected along a latitudinal sea-ice gradient across the Barents Sea in August 2019, spanning ice-free to fully ice-covered stations. δ13C values varied strongly along the sampling transect in all three FAs (16:1(n-7): -32.2 to -28.9 ‰, 20:5(n-3): -37.4 to -29.8 ‰, 22:6(n-3): -34.7 to -29.3 ‰) and, independently of the FA, were consistently higher at ice-covered (δ13C: - 30.2 ± 1.1 ‰) vs. ice-free stations (δ13C: -33.8 ± 2.2 ‰). This was likely the result of the contribution of ice-associated algae to PPOM due to ice melt as ice algae often have higher δ13C values than pelagic algae. Latitudinal differences in δ13C values of 20:5(n-3) and 22:6(n-3) displayed a similar trend, which partly differed from 16:1(n-7). This was likely related to differences in FA synthesis pathways and cellular functions between the membrane-associated FAs 20:5(n-3) and 22:6(n-3) and the storage FA 16:1(n-7). The δ13C values presented here are intended to support future food-web studies applying stable isotope mixing models to quantify carbon sources in the polar marine environment.
Keywords: Arctic Ocean, carbon isotopic composition of fatty acids, Particulate Organic Matter, sea ice, fatty acid synthesis
Received: 29 Jun 2025; Accepted: 14 Nov 2025.
Copyright: © 2025 Kohlbach, Lebreton, Guillou, Wold, Hop, Graeve and Assmy. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Doreen Kohlbach, doreen.kohlbach@awi.de
Benoit Lebreton, benoit.lebreton@univ-lr.fr
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