Sources and seasonality of long-chain diols in a temperate lake (Lake Geneva)

• 1,13- and 1,15-diols are seasonally produced during water-column stratification. likely by several species of eustigmatophytes. Diatoms unlikely to be 1,14-diol producers in Lake Geneva. Long-chain diols (LCDs) lipids commonly found freshwater environments. They lake waters low water-flow regions rivers but their sources the controls on abundance poorly constrained. To able use LCD as environmental proxy (e.g. for reconstructing temperature a indicator marine systems) we need understand these LCDs processes controlling distribution. Therefore, performed seasonal study suspended particulate matter Geneva, temperate at border France Switzerland 2017–2018. were most abundant surface water from late spring early autumn, coinciding with thermal stratification column. Their distribution varied throughout year, which points towards multiple producers. Incubation 13 C-labelled bicarbonate only showed uptake inorganic carbon peak abundance. An 18S rRNA gene amplicon analysis revealed that eustigmatophytes, known LCDs, present Geneva show same trend indicating algae important this lake. In combination previous studies our results suggest potential trace changes stratification, validate C 32 1,15-diol input lakes sediments.