Occurrence of 1-O-monoalkyl glycerol ether lipids in ocean waters and sediments

The occurrence of 1-O-monoalkyl glycerol ethers (MAGEs) in marine sediments is typically attributed to the presence of sulfate reducers. However, little is known about other possible sources within the marine realm. We have examined the concentrations and distributions of MAGEs in suspended particulate organic matter from surface water and underlying sediments of the Southern Ocean and the eastern South Atlantic Ocean. MAGEs (including monounsaturated, diunsaturated and branched) were found in surface water from both settings, suggesting a planktonic source, likely aerobic bacteria. Supporting this, we found a significant correlation between the concentrations of phytoplankton biomarkers and MAGEs. MAGE distributions in Southern Ocean and South Atlantic surface water differed, with longer chain length and more unsaturated components in Southern Ocean water, which we suggest could be an adaptation to lower surface temperature. Sedimentary MAGE distributions were significantly different from those of overlying water, which we propose to be the result of an additional sedimentary source. However, MAGEs were present in both oxic and nitrogenous–ferruginous sediments, suggesting other bacterial sources besides sulfate reducers.