Coral reefs are one of the most significant ecosystems in the ocean,and they play an essential role in preserving marine biodiversity,regulating marine climate,and developing tourism economy.In recent years,due to global climate change and increased human disturbance,coral reefs in the South China Sea deteriorate rapidly.Taking coral reefs of Xidao Island,Hainan Province,South China as an example,we extracted coral reef substrates in object-based image analysis(OBIA)method from Sentinel-2 time-serial satellite images in 10-m spatial resolution,and analyzed the change of the reef area of Xidao Island in two periods:December 2017～March 2018 and December 2021.The classification results in the end of 2021 were verified with field survey data,and the total classification accuracy and Kappa coefficient were 83.3％and 0.71,respectively.By comparing the classification results from two separate periods,we discovered that the coral coverage on the west side of Xidao Island showed no obvious variation,while it presented a recovery trend on the east.This study implied that an integrated application of 10-m spatial resolution satellite images and OBI A classification method,to some extents,can meet the requirement of information extraction related to coral monitoring and variation detection on a regional scale,and the monitoring results can provide a reference for coral conservation and restoration on Xidao Island and other small islands and reefs around Hainan Island.
维普
万方数据