Search

Harmful algal blooms (HABs) in the Southern Yellow Sea (SYS) have shown a trend of increasing diversity and detrimental effects. While the Bohai Sea, East China Sea, and South China Sea have experienced a high incidence of HABs since the 1980s, the Yellow Sea provides a relatively healthy ecological environment in which fewer HABs have been documented before the 21st century. Yet large-scale blooms of the green macroalga Ulva prolifera (so-called "green tides") have occurred annually since 2007 in the Yellow Sea. Six people were poisoned and one person died in Lianyungang in 2008 due to ingestion of algal toxins. Moreover, the Yellow Sea experienced co-occurrence of harmful red tides, green tides, and golden tides in 2017. This combination of events, rare worldwide, indicates the potential for further deterioration of the marine environment in the Yellow Sea, which may be related to climate change, aquaculture, and other human activities. Using the SYS as an example, we collected data of the frequency and scale of HABs over the years, as well as that of marine algal toxins, and analyzed the trend in the diversity of HABs in the SYS, to explore the causes and impacts of HABs, as well as the interrelationships among different types of HABs, including harmful red tides, green tides, and golden tides. We also attempted to improve our understanding of HAB evolution under the influence of global climate change and intensified human activities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]