Alkenone and tetraether lipids reflect different seasonal seawater temperatures in the coastal northern South China Sea

We examined the lipid-based temperature proxies U 37 K ′ and TEX 86 H in five short sediment cores from the inner shelf of the northern South China Sea and related them to local sea water temperature from the World Ocean Atlas (WOA) database. The U 37 K ′ -based temperature values are consistent with euphotic zone temperature in spring and summer, when the southeast monsoon prevails and vertical stratification occurs in the water column, whereas TEX 86 H -based temperature values reflect sea surface temperature in winter when the northeast monsoon prevails and vertical mixing occurs. The different temperature signals between the TEX 86 H and U 37 K ′ proxies could be a result of differences in the growing season between the source organisms, with alkenone-producing haptophyte algae blooming in the warmer and nutrient-rich season with higher fluvial influx, and tetraether-producing Thaumarchaeota blooming in the cooler and oligotrophic season.