Comprehensive Study of Algal Blooms Variation in Jiaozhou Bay Based on Google Earth Engine and Deep Learning

Abstract Jiaozhou Bay is one of China's most important marine ecosystems, experiencing increasingly prominent harmful algal blooms due to water quality deterioration and eutrophication. This study utilized the floating algae index (FAI), which was calculated from MODIS and Sentinel-2 satellite image datasets, to analyze the spatial and temporal variation of harmful algae blooms in Jiaozhou Bay between 2000 and 2022. The study discovered that the frequency of planktonic algal outbreaks was low and constant until 2017, but has increased annually since then. Algae blooms are most common in the summer, and the outbreak area is primarily concentrated in the bay's coast, middle and mouth, with obvious seasonal and spatial distribution characteristics. Several factors influencing algal outbreaks were identified in the study, including sea surface temperature, wind speed, air pressure, dissolved oxygen, nitrogen and phosphorus ratios, chemical oxygen demand (COD), and petroleum pollutants. Furthermore, according to the study, algal bloom outbreaks in Jiaozhou Bay are expected to remain high in 2023. Overall, the findings of this study provide crucial information for the management of water quality, as well as the prediction and prevention of future algal outbreaks in Jiaozhou Bay.