Spatial Change Analysis of Porphyra yezoensis Aquaculture in the Lianyungang Coastal Area by the Use of Remote Sensing and Geographic Information System Technology

Abstract

The rapid expansion of Porphyra yezoensis aquaculture in China has changed the sea surface landscape and caused inefficient sea-area usage. Thus, there is urgent to reasonably explore and utilize marine resources, protect marine ecology, and regulate the magnitude of sea-area usage. We monitored the spatial distribution of Porphyra yezoensis aquaculture and analyzed the spatial expansion patterns in the Lianyungang coastal area. It was found that the retrieval precisions of Porphyra yezoensis aquaculture based on the object-oriented classification method for 2002, 2008, 2013, and 2016 were 86.6%, 92.6%, 91.5%, and 94.8%, respectively. The spatial distribution domain has expanded and extended into the deep sea. The spatial expansion directions were to the NE around Qinshan Island, to the NW around Liandao Island, and to the NE around the Tianwan nuclear power plant. The highest spatial expansion degree was 0.29 around Liandao Island. The spatial center of gravity transfer index and transfer distance (TD) around three regions were discussed and showed the different transfer directions and the TDs. Further, there have been some conflicts between Porphyra yezoensis aquaculture and marine functional zoning in the Ganyu Port Shipping Area. The four driving factors causing the expansion and conflicts are natural conditions, cultivation techniques, economic development, and social progress. These results will help marine resource managers and municipal officials identify illegal use of sea areas and change unreasonable sea-area usage through digitalizing, visualizing, and networking of the sea-area usage.