A 50-year temporal record of dinoflagellate cysts in sediments from the Changjiang estuary, East China Sea, in relation to climate and catchment changes

Dinoflagellate cysts (dinocyst) are often used to trace environmental history within the marine realm. However, the recognition of a eutrophication signal in dinocyst records is ambiguous. In addition, as few studies have focussed on the climate signal as recorded by dinocyst proxies over a moderately short time scale, a moderately short temporal record of dinocysts in sediments from two cores recovered in the Changjiang estuary, East China Sea was investigated. Total cyst concentrations and Paralytic Shellfish Poison (PSP) cyst concentrations increased with eutrophication, and total cyst concentrations, run-off from the Changjiang River and Oceanic Niño Index peaks co-occurred. Total cyst concentrations and PSP cyst concentrations may be a potential eutrophication signal in subtropical estuaries and the climate signal could be recorded in the cyst assemblages in estuaries within a moderately short time scale as the run-off from rivers and their nutrient load changed over time.