The dynamics of red Noctiluca scintillans in the coastal aquaculture areas of Southeast China

摘要

Noctiluca scintillans(NS)adds an aes-thetic appeal to many coastal areas because of their bioluminescence.An intense bloom of the red NS frequently occurs in the coastal aquaculture region of Pingtan Island in Southeastern China.However,when NS exceeds in abundance,it causes hypoxia which has devastating impacts on the aquaculture.This study was conducted in the Southeastern part of China with an aim to examine the relationship between the profusion of NS and its impacts on marine environ-ment.Samples from four stations on Pingtan Island were collected for 12 months(January to December 2018)and were later analyzed in laboratory against five parameters,namely temperature,salinity,wind speed,dissolved oxygen,and chlorophyll a.Resultsshowed that the NS blooms were particularly active during the months of May and June in the Pingtan Island area.The seawater temperatures during that time were recorded between 20 and 28.8 ℃ indicat-ing the optimum survival temperature for NS.The NS bloom activity ceased above 28.8 ℃.A principal component analysis(PCA)indicated that the richness of NS was positively associated with temperature and salinity,whereas there was a significant reverse cor-relation between NS accumulation and wind speed.NS is a heterotrophic dinoflagellate and relies on the predation of algae for reproduction;therefore,a sig-nificant correlation was observed between NS abun-dance and chlorophyll a concentration,and an inverse correlation was observed between NS and phyto-plankton abundance.Additionally,red NS growth was observed immediately following the diatom bloom,suggesting that phytoplankton,temperature,and salinity are the essential factors in the evolution,progression,and termination of NS growth.