Temporal and spatial characteristics of harmful algal blooms in Guangdong coastal area

Based on the historical analysis of harmful algal blooms (HABs) in Guangdong coastal areas from 1980 to 2017, it is found that HABs occurred mainly in Pearl River Estuary, Dapeng bay and Daya bay waters.Guangdong coastal areas could be divided into high frequency region of diatom bloom (western Guangdong), dinoflagellate bloom (central Guangdong) and Chrysophyta bloom (eastern Guangdong) areas.HABs occurred almost every year in the central region of Guangdong (the Pearl River Estuary, Dapeng bay and Daya bay) from 1980 to 2017.The main HABs was no longer diatom bloom in Dapeng bay after 2000, and shifted from diatom blooms to dinoflagellate blooms in Daya bay after 2002.In contrast, HABs stared to occur frequently in the eastern and western Guangdong after 2000.The seasonal occurrence of HABs was different in different regions.In the western Guangdong (Zhangjiang), diatom blooms occurred mainly in summer.In the central Guangdong, toxic and detrimental blooms occurred mainly in Pearl River Estuary in spring; Noctiluca scintillans blooms occurred mainly in Dapeng bay in spring; Scrippsiella trochoidea blooms mainly occurred in Daya bay in summer and autumn.In the eastern Guangdong, P.globosa blooms occurred in the whole year.Based on the temporal and spatial characteristics of HABs in Guangdong coastal areas, we could provide important information for the management of HABs and suggestions for better utilization and protection of marine resources in different regions of Guangdong province.