The Holocene sedimentary record of cyanobacterial glycolipids in the Baltic Sea: an evaluation of their application as tracers of past nitrogen fixation
Sollai, M.; Hopmans, E.C.; Bale, N.J.; Mets, A.; Warden, L.; Moros, M.; Sinninghe Damsté, J.S. (2017). The Holocene sedimentary record of cyanobacterial glycolipids in the Baltic Sea: an evaluation of their application as tracers of past nitrogen fixation. Biogeosciences 14(24): 5789-5804. https://doi.org/10.5194/bg-14-5789-2017
In: Gattuso, J.P.; Kesselmeier, J. (Ed.) Biogeosciences. Copernicus Publications: Göttingen. ISSN 1726-4170; e-ISSN 1726-4189, more
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| Authors | | Top |
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- Warden, L., more
- Moros, M.
- Sinninghe Damsté, J.S., more
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| Abstract |
Heterocyst glycolipids (HGs) are lipids exclusivelyproduced by heterocystous dinitrogen-fixingcyanobacteria. The Baltic Sea is an ideal environment tostudy the distribution of HGs and test their potential asbiomarkers because of its recurring summer phytoplanktonblooms, dominated by a few heterocystous cyanobacterialspecies of the genera Nodularia and Aphanizomenon.A multi-core and a gravity core from the Gotland Basinwere analyzed to determine the abundance and distributionof a suite of selected HGs at a high resolution to investigatethe changes in past cyanobacterial communities during theHolocene. The HG distribution of the sediments depositedduring the Modern Warm Period (MoWP) was comparedwith those of cultivated heterocystous cyanobacteria, includingthose isolated from Baltic Sea waters, revealinghigh similarity. However, the abundance of HGs droppedsubstantially with depth, and this may be caused by eithera decrease in the occurrence of the cyanobacterial bloomsor diagenesis, resulting in partial destruction of the HGs.The record also shows that the HG distribution has remainedstable since the Baltic turned into a brackish semi-enclosedbasin ?7200 cal. yr BP. This suggests that the heterocystouscyanobacterial species composition remained relativelystable as well. During the earlier freshwater phase of theBaltic (i.e., the Ancylus Lake and Yoldia Sea phases),the distribution of the HGs varied much more than in thesubsequent brackish phase, and the absolute abundance ofHGs was much lower than during the brackish phase. Thissuggests that the cyanobacterial community adjusted to thedifferent environmental conditions in the basin. Our resultsconfirm the potential of HGs as a specific biomarker ofheterocystous cyanobacteria in paleo-environmental studies. |
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