Harmful Dinoflagellate Prorocentrum donghaiense Lu is Widely Distributed Along the East China Sea and Korean Coastal Area

There have been controversies regarding the taxonomy of Prorocentrum donghaiense , however Zhang et al. (2016) recently developed a probe with a quantitative real-time PCR (qPCR) assay that targets the D1–D2 region of the large subunit (LSU) rDNA of this species. We used this qPCR assay to determine the spatial distribution and abundance of P. donghaiense along the East China Sea (ECS) and Korean coastal area. During 15–22 May 2017, surface water samples were collected to extract genomic DNA and subsequent qPCR at 29 stations of the ECS and Korean coastal area, and the water temperature and salinity were also recorded at the time of sampling. The morphological features of P. donghaiense collected from the study area were identical to those of P. shikokuense and P. donghaiense reported in previous studies. Higher cell densities were recorded at water temperatures of 14.8 to 19.3°C and at salinity of 32.3 to 34.0, indicating that P. donghaiense can grow in a broad range of water temperatures. In addition, relatively higher cell densities were generally observed within stations that are affected by the Changjiang Diluted Water and Taiwan Warm Current flows, and low cell densities were prominent near the Japanese coast that is affected by the Tsushima Current flow and in the southwest coast of Korea. These results suggest that P. donghaiense occurs throughout a broad area of the ECS and Korean coastal area, and the current flows in the ECS may stimulate P. donghaiense blooms.