Remote Sensing Monitoring Of The Spatial And Temporal Changes And Ecological Impact Analysis Of Coastal Aquaculture In Hainan Island

The increasing demand for aquatic products provides an ideal development space for the aquaculture industry.At present,the aquaculture industry has become one of the fastest growing sectors in the world’s food production.Especially in the near-shore areas,the aquaculture industry has rapidly started due to the suitable environment and abundant natural resources.The coastal area is a land-sea border zone,and the ecosystem is fragile.The development of the aquaculture industry has created economic benefits while also causing serious environmental problems,which has largely restricted the healthy development of the aquaculture industry.Therefore,it is of great significance to monitor the current status of aquaculture development in coastal areas.Hainan is located at the southernmost tip of China.It is an ideal place for China to develop tropical marine fisheries.Aquaculture industry is developed in Hainan,but environmental problems such as high farming density and farming wastewater discharge are becoming increasingly prominent.Mastering the development of Hainan’s aquaculture industry and evaluating its ecological impact is an important basis for scientifically and rationally developing and protecting the ecological environment in the coastal areas of Hainan.This paper uses Landsat Satellite imagery,combined with domestic GF satellite imagery,Google Earth satellite imagery,land use and water quality data and other auxiliary data,based on the Google Earth Engine cloud platform to extract aquaculture information fron 1987-2018 in Hainan Island and analyzed the change characteristics in time and space,then analyzed the impact of aquaculture on the coastal ecological landscape and coastal water environment,The main findings of this paper are as follows:(1)From 1987 to 2018,the area of aquaculture in the coastal area of Hainan Island increased significantly,and the area increased by 22,605 hectares in 31 years,of which the fastest growth period was 1995-2015;after 2015,the area of aquaculture decreased slightly.The distribution of the aquaculture area near the coast of Hainan Island is characterized by"more east and less west" and the development speed is uneven.The center of mass of the aquaculture area has moved 72.9km to the northeast,and the landscape pattern of the aquaculture area has become more complex.The industry has developed in a disorderly state for a long time.(2)The rapid expansion of aquaculture has had a negative impact on the coastal ecological landscape and water environment of Hainan Island.From 1990 to 2015,a large amount of coastal land was converted into aquaculture ponds,resulting in a large amount of land loss.The competitive relationship between aquaculture ponds and mangroves is the most significant.The expansion of aquaculture has become the main reason for the reduction of mangrove areas.The concentration of chlorophyll-a can reflect the eutrophication of seawater.The aquaculture area of Hainan Island has a positive correlation with the concentration of chlorophyll-a in the coastal area,and the correlation decreases with the increase of the offshore distance,indicating that aquaculture causes the proliferation of phytoplankton and causes seawater eutrophication.(3)For a long time,the lack of scientific management and policy support is an important reason for the ecological damage caused by the development of the aquaculture industry in Hainan.In recent years,The ecological restoration work has been continuously carried out in Hainan.This paper monitors the ecological restoration status of Hainan Island based on high-resolution data from Google Earth.We found that after 2010,the work of"returning aquaculture ponds to forests" and "returning aquaculture ponds to wetlands" in Dongzhai Port,Tielu Port and other regions has achieved certain results,and the aquaculture industry in Hainan will become more scientific and standardized.This study reveals the characteristics of the spatial and temporal changes of the aquaculture area of Hainan Island and its impact on the coastal area ecological environment over the past 30 years.It can provide a scientific basis for a better understanding of Hainan Island’s fishery development planning.At the same time,it can provide information support for promoting the scientific development and transformation of the aquaculture industry in Hainan Island and promoting the sustainable development of the coastal economy.