Temporal and vertical variations of lipid biomarke

Authors: Thomas A Brown Simon T Belt Benoît Philippe Christopher J Mundy Guillaume Massé Michel Poulin Michel Gosselin

Publish Date: 2010/12/30

Volume: 34, Issue: 12, Pages: 1857-1868

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Abstract

Variations in the concentrations of the sea ice diatom biomarker IP25 Ice Proxy with 25 carbon atoms were measured in the bottom 10 cm of sea ice collected from the eastern Beaufort Sea and Amundsen Gulf from January to June 2008 as part of the International Polar Year–Circumpolar Flaw Lead system study Temporal and vertical changes in IP25 concentrations were compared against other biomarkers and indicators of ice algal production IP25 was not detected in sea ice samples collected from midwinter to early spring likely as a result of lightlimiting conditions for algal growth and accumulation From early March to midJune IP25 concentrations correlated well with those of fatty acids r = 079 P  0001 less so with total sterols r = 063 P  0001 and qualitatively with chlorophyll a concentrations and diatom cell abundances from adjacent sea ice cores Approximately 90 of the total sea ice IP25 accumulation occurred from midMarch to lateMay coincident with the ice algal bloom period The majority ca 87–93 of IP25 was biosynthesised within the lower 5 cm of the sea ice where brine volume fractions were 5 which is consistent with the hypothesis that brine channel connectivity limits the internal colonisation of sea ice by diatoms Maximum IP25 concentrations occurred at 1–3 cm from the ice–water interface providing further evidence for a selective sea ice diatom origin for this biomarker In contrast vertical concentration profiles for fatty acids and sterols indicated mixed sources for these biomarkersWe thank the Natural Environment Research Council NERC UK for funding part of this work NE/D013216/1 LSMSBRIS026 04/08 and for providing a PhD studentship to TB NE/F007043/1 This work was also supported through grants from the Canadian International Polar Year–Federal government program office and the Natural Sciences and Engineering Research Council NSERC of Canada to MG and MP and financial help from the Canadian Museum of Nature to MP Partial operating funds for the CCGS Amundsen were provided by the International Joint Ventures Fund of the Canada Foundation for Innovation and the Fonds Québécois de la Recherche Sur la Nature et les Technologies FQRNT We would like to extend our gratitude to the officers and crew of the CCGS Amundsen for their invaluable support during the expeditions We are also particularly grateful to Dr JÉ Tremblay and S Pineault from the Université Laval Canada for providing us with filtered sea ice samples for the period 12 April to 8 May 2008 and to Andrea and Greg Niemi and C Michel for collection of early sea ice samples We thank Dr I Bull and J Williams from the University of Bristol NERC LSMSF facility for analyses of stable carbon isotopes by GC–IRM–MS This work is a contribution to the International Polar YearCircumpolar Flaw Lead system study IPYCFL We thank three anonymous reviewers for providing helpful suggestions to improve this manuscript

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