Spatio-temporal Variations Of Shoreline And Habitat Fragmentation Along The Coastal Areas Of The Bohai Sea,China

Affected by the economic development of coastal areas,the expansion of urban land use and the sharp increase in population density,the reclamation activities rapidly expanded rapidly in the coastal areas due to their low cost and large social and economic dividends.However,the artificial surface landscape that appeared in the coastal area for a short time not only quickly reshaped the land cover type of the coastal zone,changed the material energy flow between the land and the sea in the coastal zone,affected the time and space changes of the coastline,and profoundly changed the coastal area.The type of landscape in the wetland area is aggravated by the fragmentation of the habitat.This study shows that due to the impact of reclamation activities,the artificial coastline in the Bohai Sea area increases rapidly,the natural coastline decreases rapidly,and the coastline expands rapidly toward the ocean.The geometric center of gravity of the bay moves rapidly to the middle of the ocean,and the geometry of the bay is more complicated.The reclamation project has been rapidly expanding in the coastal area of the Bohai Sea since 2000;the coastal wetland landscape pattern has been significantly fragmented,showing a rapid increase in the number of artificial patches,an increase in density,an increase in the average area,and a complicated geometric shape.And other characteristics.The specific results are as follows:1.Based on the Digital Shoreline Analysis System(DSAS),this paper studies the temporal and spatial variation of the shoreline of the Yellow River Delta and Laizhou Bay.Results show that:by extracting the Landsat 6 images from 1985 to 2015,it was found that the shoreline of the Yellow River Delta and Laizhou Bay showed a significant trend of expanding to the sea in the past 30 years,and the growth rate was accelerated.(1)The average of the End Point Rate(EPR)was about 73.0 m/a,and the linear regression rate(LRR)was about 75.48 m/a.The growth rate of the Yellow River port-Dazui ditch was the fastest(129.2 m/a).Due to the influence of the sediment transport in the Yellow River,the shoreline's geometric shaped of the Yellow River estuary and the old Yellow River estuary showed a smooth trend;(2)The average growth in the Laizhou Bay was about 139.5 m/a(EPR)and 144.3 m/a(LRR).The growth rate of the Zimai-Bailang section was the fastest(197.6 m/a).The areas with relatively significant changed in shoreline are concentrated in areas such as ports,seawall dams,mariculture,etc.DSAS model had a significant advantage in the quantitative analysis of shoreline.EPR and LRR indicators can scientifically and effectively simulated the time and space rate of shoreline2.The spatial-temporal variations of the shoreline and land reclamation in the Bohai Sea were analyzed based on 49 Landsat images of 7 periods from 1985 to 2015.The following conclusions were drawn.(1)The shoreline that was extracted based on visual interpretation had high precision,and the error could be controlled within the theoretical range.(2)Over the past 30 years,the shoreline of the Bohai Sea exhibited an average rate of change of 188.47 m/a and an average accretion distance of 3,554.27m toward the sea.The fastest rate of shoreline change occurred in Laizhou Bay(134.78m/a),followed by Bohai Bay(128.20 m/a)and Liaodong Bay(61.69 m/a).(3)The average rate of reclamation was 32.46×10~3 hm~2/a in the Bohai Sea,where the total area of aquaculture land,unused land,and salt land exceeded 60%of the total reclamation area.(4)The geometric shape of the bay became increasingly more complicated year to year,and the geometric center of gravity of the bay moved rapidly toward the sea.In addition,the area of the bay also showed a significant declining trend.In order to protect the function and structure of eco-system in the coastal region,we must control the scale and increasing rate of land reclamation in the future.3.Based on 49 Landsat remote sensing images from 1985 to 2015,the datasets of the spatial and temporal distribution of reclamation activities in the Bohai Sea area were extracted.Based on the data from 1982 to 2017,Ichthyoplankton Data(ID)The effects of reclamation activities on early fish supplementation;using Habitat Fragmentation(HF)indicators and Principal Component Analysis(PCA)models to study the effects of reclamation activities on the fragmentation of coastal wetland landscape patterns Finally,based on the HF index and ID,the First Principal Component(FPC)explains the relationship between reclamation activities and fish plankton.The results show that the number of plaques in the coastal reclamation project increases rapidly,the average area increases,the geometric shape is complex,the spatial aggregation increases,and the density increases.Compared with different types of plaques,the rupture index of industrial plaques and port plaques increased the fastest,the plaques of aquaculture land and salt field plaques were relatively small,and the unused plaques of cofferdams showed strong plaques.Fluctuation trend.Since 2000,the Bohai Sea reclamation project has shown a significant growth trend.At that time,the area of unused abandonment land and salt field for aquaculture land exceeded 60%of the total area of reclamation.There is a close negative correlation between the degree of habitat fragmentation and the quantity and abundance of fish stocks in the early stage of fishery resources.This may be due to the close relationship between the early habitats of fish and habitats caused by reclamation activities.