With the development of industrialization and aquaculture in Jiangsu and Shandong Provinces along the South Yellow Sea coast,China,eutrophication has greatly intensified in the region,resulting in frequent occurrence of diverse harmful algal blooms.An algal bloom formed by a chain-forming dinoflagellate species was recorded in the Haizhou Bay,South Yellow Sea,in September 2020.The causative species was isolated and studied in morphology,molecular phylogeny,pigment profile,presence of paralytic shellfish toxins,and acute toxicity.The loop-shaped apical groove running anticlockwise around the apex,the presence of peridinin as characteristic pigment,as well as a single phylogenic clade of 28S ribosomal DNA(100％posterior probability),defined this species as Gymnodinium impudicum,a non-toxic species that exhibited no obvious biotoxicity to the rotifer Brachionus plicatilis,the copepod Artemia salina,and the shrimp Neomysis awatschensis.Gymnodinium impudicum is typically distributed in coastal waters with high nitrate concentrations,where it reaches a maximum density of 2.6×105 cells/L.This is the first report of a G.impudicum bloom in the Yellow Sea;however,G.impudicum blooms may have been misidentified or underreported in Haizhou Bay due to the species morphological similarity with G.catenatum.A combination of multiple methods is recommended to accurately identify new algal bloom species.

Jinxiu WANG;Fanzhou KONG;Yunfeng WANG;Nanjing JI;Minjie SONG;Zhangxi HU;Zhuang NIU;Chao LIU;Xin WANG;Yuanyuan SUN;Rencheng YU;Tian YAN

CAS Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Laboratory for Marine Ecology and Environmental Science,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China;Jiangsu Key Laboratory of Marine Biological Resources and Environment,Jiangsu Ocean University,Lianyungang 222005,China;CAS Key Laboratory of Experimental Marine Biology,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China

海洋湖沼学报（英文版）

[1]Jinxiu WANG;Fanzhou KONG;Yunfeng WANG;Nanjing JI;Minjie SONG;Zhangxi HU;Zhuang NIU;Chao LIU;Xin WANG;Yuanyuan SUN;Rencheng YU;Tian YAN-.Newly recorded bloom-forming dinoflagellate Gymnodinium impudicum in Haizhou Bay,Yellow Sea,China)[J].海洋湖沼学报（英文版）,2022(06):2430-2445

impudicum,Haizhou,peridinin,phylogenic,rotifer,Neomysis,awatschensis,misidentified

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