Use of Stress Signals of Their Attached Bacteria to Monitor Sympagic Algae Preservation in Canadian Arctic Sediments

• Published in: Microorganisms
• Main Authors: Rémi Amiraux, Bonin Patricia, Burot Christopher, Rontani Jean-François
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: sympagic algae; Arctic; bacterial stress; lipid tracers; sediments; preservation; Biology (General); QH301-705.5; Global warming; Sea ice
• Online Access: https://doi.org/10.3390/microorganisms9122626; https://doaj.org/article/609d4c0aed3843b2974163bf1c9fcede

Based on the strong aggregation of sympagic (ice-associated) algae and the high mortality or inactivity of bacteria attached to them, it was previously hypothesized that sympagic algae should be significant contributors to the export of carbon to Arctic sediments. In the present work, the lipid content of 30 sediment samples collected in the Canadian Arctic was investigated to test this hypothesis. The detection of high proportions of trans vaccenic fatty acid (resulting from cis-trans isomerase (CTI) activity of bacteria under hypersaline conditions) and 10 S -hydroxyhexadec-8( trans )-enoic acid (resulting from 10 S -DOX bacterial detoxification activity in the presence of deleterious free palmitoleic acid) confirmed: (i) the strong contribution of sympagic material to some Arctic sediments, and (ii) the impaired physiological status of its associated bacterial communities. Unlike terrestrial material, sympagic algae that had escaped zooplanktonic grazing appeared relatively preserved from biotic degradation in Arctic sediments. The expected reduction in sea ice cover resulting from global warming should cause a shift in the relative contributions of ice-associated vs. pelagic algae to the seafloor, and thus to a strong modification of the carbon cycle.