YANG Xiankun, LIN Rongjian, WANG Dakang, YANG Yingpin, WANG Jinnian
Journal of Guangzhou University(Natural Science Edition). 2025, 24(6): 1-12.
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The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is one of the most economically active regions in China. Its extensive fish pond aquaculture activities play an important role in the sustainable supply of regional aquatic products. However, the carbon balance contribution caused by the high-intensity aquaculture activities in these fish ponds is still lacking in quantitative research. This study used the Sentinel-3 Ocean and Land Colorimeter (OLCI) data, combined with a semi-analytical inversion algorithm based on key bands (Oa08, Oa09, Oa017), and performed atmospheric correction through the SeaDas software to improve the reflectance accuracy, providing reliable data for carbon concentration inversion, and then estimating the carbon concentration of phytoplankton in fish ponds in the GBA from 2016 to 2024.The results show that: ① Overall, the carbon concentration of phytoplankton in fish ponds in the GBA presents a spatial distribution of high in the northwest and low in the southeast, mainly showing a trend of gradually weakening from inland cities to coastal cities, and the concentration differences between different cities are obvious. ② The seasonal changes in the carbon concentration of phytoplankton in aquaculture fish ponds in the GBA are more significant than the interannual changes. The high concentration season is autumn, with an average concentration of 2.193 mg/L; followed by summer and winter, with 1.314 and 1.465 mg/L respectively; the lowest concentration is in spring, which is 0.632 mg/L. ③ The high concentration areas are mainly distributed in inland areas such as Zhaoqing City and Foshan City in the northwest, and the low concentration is mainly distributed in the coastal areas in the southeast. ④ The interannual variation of phytoplankton carbon concentration showed a statistically insignificant increasing trend, and showed a slight upward trend year by year in the Sen's slope estimation, with an annual increase rate of 0.01~0.05 mg/L, mainly concentrated in Huizhou, Foshan and Hong Kong. The study verified the application potential of the Sentinel-3 OLCI satellite in estimating carbon flux in aquaculture areas, clarified the spatiotemporal dynamic changes of phytoplankton carbon concentration in small fish pond ecosystems, and its important impact on the regional carbon cycle. The results provide a scientific basis for optimizing environmental management in the GBA and studying carbon dynamics in similar aquaculture systems.