The dinoflagellate Noctiluca scintillans blooms nearby Pingtan, Fujian from April to June regularly but the scales vary interannualy. A massive Noctiluca scintillans bloom broke out in April 2022, as confirmed by light microscopy, which affected the local fishery to a certain extent. The breakout of Noctiluca scintillans blooms in Pingtan is attributed to the combined effect by nutrients, hydrology, meteorology and other factors. Especially rich nutrients input from the Minjiang River through the Zhemin Coastal Current has promoted the diatom blooms and provided food source of Noctiluca scintillans. The nutrient content in the Taiwan Strait, including inorganic phosphorus (>0.4μmol/L) silicate (>30 μmol/L) and inorganic nitrogen (>20 μmol/L) are much higher near the Minjiang Estuary in April 2022 than in the same period of 2021. To investigate the mechanism driving the massive blooms of Noctiluca scintillans, the hydrodynamic model FVCOM (Finite Volume Community Ocean Model) was coupled with the ecological model ERSEM (European Regional Seas Ecosystem Model) to describe the physical biogeochemical process of the Taiwan Strait. The simulation experiments demonstrated that Noctiluca scintillans blooms in Pingtan were positively related with the sea surface temperature (SST) of Taiwan Strait, and the transport of nutrients by tides and the coastal current in northwest Taiwan Strait has promoted the blooms in Pingtan. Combined with the satellite remote sensing data and in-situ measurements, the model results demonstrated that the high concentration of the chlorophyll a (Ch1-a) near the Minjiang Estuary in April 2022 was contributed mainly by diatoms and dinoflagellates, and inorganic nitrogen played a key role in regulating the growth of phytoplankton. Sea surface wind (SSW) anomaly affected the vertical mixing and changed the distribution of nutrient, and the abnomal warming of Taiwan Strait favored the continued growth of Noctiluca scintillans. The extreme Noctiluca scintillans blooms in Pingtan, Fujian in April 2022 could partly be associated with La Nina climate anomaly. This study highlight the importance of climate change on Noctiluca scintillans blooms in Taiwan Strait, and provided scientific basis for predicting the occurrence of Noctiluca scintillans blooms in Pingtan sea area.

Keywords: Noctiluca scintillans blooms, FVCOM, ERSEM, Taiwan Strait