Biomarkers reveal the effects of hydrography on the sources and fate of marine and terrestrial organic matter in the western Irish Sea

Shane S. O'Reilly, Michal T. Szpak, Paul V. Flanagan, Xavier Monteys, Brian T. Murphy, Sean F. Jordan, Christopher C R Allen, Andre J. Simpson, Stephen M. Mulligan, Sara Sandron, Brian P. Kelleher*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


A suite of lipid biomarkers were investigated from surface sediments and particulate matter across hydrographically distinct zones associated with the western Irish Sea gyre and the seasonal bloom. The aim was to assess the variation of organic matter (OM) composition, production, distribution and fate associated with coastal and southern mixed regions and also the summer stratified region. Based on the distribution of a suite of diagnostic biomarkers, including phospholipid fatty acids, source-specific sterols, wax esters and C25 highly branched isoprenoids, diatoms, dinoflagellates and green algae were identified as major contributors of marine organic matter (MOM) in this setting. The distribution of cholesterol, wax esters and C20 and C22 polyunsaturated fatty acids indicate that copepod grazing represents an important process for mineralising this primary production. Net tow data from 2010 revealed much greater phytoplankton and zooplankton biomass in well-mixed waters compared to stratified waters. This appears to be largely reflected in MOM input to surface sediments. Terrestrial organic matter (TOM), derived from higher plants, was identified as a major source of OM regionally, but was concentrated in proximity to major riverine input at the Boyne Estuary and Dundalk Bay. Near-bottom residual circulation and the seasonal gyre also likely play a role in the fate of TOM in the western Irish Sea.

Original languageEnglish
Pages (from-to)157-171
Number of pages15
JournalEstuarine Coastal and Shelf Science
Early online date13 Nov 2013
Publication statusPublished - 01 Jan 2014


  • Irish Sea
  • Lipid biomarkers
  • Organic matter cycling
  • Phospholipid fatty acids
  • Plankton

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography


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