Lipid biomarker as indicator for assessing the input of organic matters into sediments and evaluating phytoplankton evolution in upper water of the East China Sea

•OMs input from both terrestrial and marine in the East China Sea were indicated by Lipid biomarkers.•Fatty acids indicated that marine input dominated much more with intensified eutrophication.•Lipid biomarkers recorded the structure of phytoplankton community overlying.•Bra/Din was a critical indicator for inversion of phytoplankton community structure.•Complex red tides composed of diatoms and dinoflagellates tended to form.