Succession of Planktonic Crustaceans Responding to Ulva Green Tide in the Subei Shoal, Southwestern Yellow Sea

The large-scale green tide (YSGT) has been persisting in the Yellow Sea over a decade, while its impacts on various trophic organisms remained inconclusive. Field surveys were conducted to investigate the dynamic of planktonic crustacean community in response to the massive blooming of Ulva biomass in the Subei Shoal and the adjacent water. A rapid change of the planktonic crustacean populations during the development process of YSGT was revealed by this study. Copepods, mysids and euphausiids, and amphipods were three major groups of the planktonic crustacean community in the survey region. Copepods were the dominant group, accounting for 82.16%±3.41% of the total biomass. The total biomass of planktonic crustaceans decreased from 70.98 mg/m³ to 7.36 mg/m³ with the bloom of Ulva algae. Copepods, mysids and euphausiids were the two groups contributing for the rapid decline. At the same time, amphipods showed evident species succession. The planktonic Themisto gaudichaudii absolutely dominated before the green tide, while the epizootic Sunamphitoe tea and Apohyale sp. succeeded during the bloom. Based on this study, the massive YSGTs seriously destructed the planktonic crustacean community and reduced the secondary productivity, which likely impaired the fishery resources and benthos through trophic chains.