SPATIOTEMPORAL AND BIOLOGICAL VARIABILITY OF RED TIDE IN TIANJIN COASTAL WATERS DURING THE PAST 15 YEARS

Red tide is a major marine ecological disaster in the coastal area which indicates the change of ecological environment. Bohai Bay is an important platform for the Beijing-Tianjin-Hebei area for regional economic integration, which is an important channel for the marine biology in the Yellow Sea and Bohai Sea. Therefore, in this work, the red tide data from 2002 to 2017 were analyzed to study the spatiotemporal distribution and the changing characteristics of biological groups in this area. In the past 15 years, the occurrence of red tide has been limited from the month of June to August. Spatially, the red tide occurrence was less common in the south than north, and the most frequent red tide event recorded from Tianjin Port channel to the northern area of Jianhe kou. The main red tide biota were dinoflagellates, diatoms and Chrysophytae and the dominant red tide species were Noctiluca scintillans, Skeletonema costatum, Phaeocystis globosa and Karenia mikimotoi. Besides, the red tide caused by toxic algae was increasing year by year. However, the high seawater temperature in summer, flood, anthropogenic nutrient influx, and favorable southwest and southeast monsoon wind positively influenced the red tide events.