Spatiotemporal Dynamics Of Coastal Aquaculture And Driving Force Analysis In The Ningde Coastal Region

Coastal region is a unique ecological transition region connecting terrestrial and marine ecosystems.Coastal ecosystems provide important ecosystem services for humans,such as seafood,defense and reduction of marine disasters,and the provision of ecotourism and leisure services.With the world's population expected to reach 9.7 billion by 2050,aquaculture products are expected to become main food.Thus,coastal aquaculture,as an important component of seafood aquaculture,has developed rapidly in recent years.However,large-scale disordered coastal aquaculture development causes severe environmental problems,such as coastal wetland loss,seawater pollution,and biodiversity reduction.It is a challenge to develope sustainable fishery economy in the coastal region.Therefore,clarifying the spatiotemporal dynamic characteristics of coastal aquaculture and its driving factors help to form standardized coastal aquaculture management,and have important reference value for promoting the sustainable development of coastal fisheries economy.Based on the high-resolution satellite remote sensing data and field survey data in 2003,2010,and 2016,the coastal region of Ningde City was studied,and the spatial and temporal patterns and dynamic changes of land use were studied in different periods.On this basis,we analyzed the overall landscape index of the Ningde coastal region and its coastal aquaculture.In addition,we also quantitatively analyzed the driving factors affecting the growth and decline of coastal aquaculture through multiple linear regression.The main conclusions of this thesis are as follows:(1)From 2003 to 2016,the construction land and forest land in the coastal region of Ningde City continued to increase at a high speed,while bare land and farmland continued to decrease,and the intensity of change in these four types was slowing down.The intensity of the overall landscape change in the coastal region from 2003 to 2010 is greater than that from 2010 to 2016.It is mainly due to relatively more drastic changes in construction land,bare land and farmland from 2003 to2010.From 2003 to 2016,the development trend of construction land and coastal aquaculture to the ocean has increased significantly.Coastal aquaculture has gradually shifted from inland expansion in the coastal region to large-scale ocean expansion.During the period,the main sources of growth in coastal reclamation were waterbody,farmland,and construction land,and attenuation was mainly used for construction land,water body,and farmland.(2)From 2003 to 2016,the growth of coastal aquaculture area in the Ningde coastal region accelerated,and its structure changed significantly.The areas of razor clam pond and artificial shrimp pond increased,while the area of farmland pond decreased.Among the three,the growth rate of artificial shrimp pond was the fastest,followed by razor clam pond.From 2003 to 2016,the area of artificial shrimp pond and razor clam pond increased by 496.15%(from 0.52 km~2 to 3.10km~2)and 12.15%(from 68.78 km~2 to 77.14 km~2),respectively.Meanwhile,the area of farmland pond decreased by 25.81%,from 21.35 km~2 to 15.84 km~2.(3)From 2003 to 2016,the change trends of the coastal aquaculture area and the entire Ningde coastal region were consistent,and became more fragmented and dispersive.At the same time,its shape becomes more complicated and irregular,reflecting that the coastal aquaculture has become more dispersed while growing.(4)Human activities were the main driving factors to change the way of land use of coastal aquaculture.The biggest driving factor for the growth and decline of the coastal aquaculture area was the initial cultivated patch area.The growth model of coastal aquaculture shows that the larger the initial cultivated patch area was,the larger the newly increased coastal aquaculture area was.In addition,the greater the distance from the nearest initial coastline,from the nearest initial coastal aquaculture patch,from the nearest initial road and from the nearest newly built port,the greater the area growth of the coastal aquaculture.The attenuation model shows that the larger the initial coastal aquaculture patch area was,the larger the attenuation area.In addition,the further away from the nearest initial road,the greater the area attenuation of coastal aquaculture.The closer the distance from the nearest new factory and the nearest new road was,the greater the attenuation of the coastal aquaculture area.The changes of coastal aquaculture areas were significantly affected by human activities,and the decline of coastal aquaculture areas were more affected by human activities.The results help to formulate a more reasonable coastal land use plan,reduce the destructive occupation of farmland and waterbody by coastal aquaculture,and promote the sustainable development of the coastal region.