Journal of Tropical Oceanography ›› 2026, Vol. 45 ›› Issue (4): 104-115.doi: 10.11978/2025200CSTR: 32234.14.2025200

• Ocean Remote Sensing • Previous Articles     Next Articles

Study on the spatial expansion mode of raft aquaculture in Qinzhou Bay since 2000 using remote sensing technology

JIN Song1(), ZOU Tao1(), LIAO Riquan2,3, CHEN Chaohao2,4, MI Huan5, TANG Jianhui1,2,3   

  1. 1 Shandong Key Laboratory of Coastal Zone Environmental Processes and Ecological Security, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
    2 Pinglu Canal and Beibu Gulf Coastal Ecosystem Observation and Research Station of Guangxi, Beibu Gulf University, Qinzhou 535011, China
    3 Guangxi Key Laboratory of Marine Environmental Disaster Processes and Ecological Protection Technology, College of Marine Science, Beibu Gulf University, Qinzhou 535011, China
    4 Qinzhou Marine Environmental Monitoring and Forecasting Center, Qinzhou 535099, China
    5 School of Civil Engineering of Yantai University, Yantai 264005, China
  • Received:2025-10-23 Revised:2025-11-24 Online:2026-07-10 Published:2026-07-31
  • Contact: ZOU Tao. email:
  • Supported by:
    National Natural Science Foundation of China(4240176); Natural Science Foundation of Shandong Province(ZR2022QD123)

Abstract:

Mapping the distribution of shallow-sea aquaculture and monitoring its spatial expansion are essential for implementing dynamic marine monitoring, improving regional aquaculture management, optimizing spatial layout, and promoting ecological conservation. This study selects Qinzhou Bay as the research area and proposes an adaptive threshold algorithm for extracting aquaculture raft frames to characterize their spatiotemporal dynamics. A raft index (RI) is constructed based on Landsat series imagery. A fuzzy clustering algorithm was employed to enhance structural features of the raft frames, and a chessboard segmentation algorithm was applied to partition the clustered RI image. The Otsu’s threshold method (OTSU) is then used to identify raft frames in the segmented images. The results reveal a significant expansion of aquaculture raft frames in Qinzhou Bay since 2000, with the maximum area reaching 7860.96 hm2 in 2022. The distribution of raft frames has expanded from the coastal waters near Longmen Town toward the outer parts of Qinzhou Bay and into the Maowei Sea (inner bay). A strong correlation was observed between the raft frame area and seawater quality in Qinzhou Bay, with coefficients of determination (r2) of 0.73 for active phosphate, 0.50 for the composite pollution index, and 0.36 for the eutrophication index. The findings of this study offer valuable insights into the spatiotemporal evolution of aquaculture raft frames in Qinzhou Bay and their relationship with the marine environment.

Key words: raft extraction, adaptive threshold algorithm, Landsat images, Qinzhou Bay

CLC Number: 

  • P714