Study On The Relationship Between Human Activity Intensity And Offshore Macroalgae Disaster In Yantai Coastal Zone

There are a long coastline and abundant coastal resources in Yantai,but the coastal zone is currently facing significant pressures.In recent years,the development and utilization of coastal areas,such as ports and docks,mariculture and other human activities have a great impact on the coastal water.And the occurrence of red tide and U.prolifera has been continuously monitored in Yantai coastal waters,which also has a serious impact on the marine ecological environment.Whether the occurrence of disasters is related to human activities in the coastal zone has aroused widespread social concern.The influence of human activity intensity on the large algae disaster in Yantai coastal zone is not clear.Therefore,in order to further study the response relationship between changes in intensity of human activities in coastal zones and macroalgae disasters,remote sensing,geographic information system technology and statistical analysis methods were used to carry out vector extraction and data statistics on the surface coverage information of coastal zone within 2 km of Yantai and the coastal macroalgae disaster information of Shandong Peninsula including Yantai in this study.On this basis,the human activity intensity model in coastal zone was constructed.At the same time,the impact of the intensity of human activities in the coastal zone on the coastal red tide and green tide disasters is analyzed.Finally,the main influencing factors of the two algae disasters are studied and discussed,and the main research conclusions are as follows.(1)According to the land cover information of Yantai coastal zone extracted from remote sensing from 2000 to 2019,the area of the study area presented a trend of rapid growth at first and then a slow increase.The area has increased from 818.11 km~2 in2000 to 984.02 km~2 in 2019.Under the influence of human activities,the monitoring area of various regions is increasing,especially the area of structures,artificial excavated land and water area.The surface cover type of coastal zone is mainly transferred from bare land and water area to structures,forest and grass cover.The intensity of human activities in the coastal zone of Yantai is increasing on the whole,and the intensity of human activities in the coastal zone of Longkou,Zhifu,Laishan and Fushan is relatively high and concentrated.In the boundary zone of different land cover types,the intensity of human activities is high due to the superposition effect of human activities.(2)The occurrence of red tide disaster in coastal waters of Yantai has a certain change rule in time and space distribution,and its influencing factors are also multi-sided and uncertain.In terms of time distribution characteristics,the number and affected area of red tide disasters increased first and then decreased from 2000 to 2019.The maximum number of red tide outbreaks occurred from 2000 to 2010,with a total of 14 outbreaks,and the cumulative affected area reached 2108.40 km~2.In terms of spatial distribution,the red tide disaster prone areas are located in the Si Shiliwan area of Yantai and the coastal area of Qingdao.The coverage area of U.prolifera in the South Yellow Sea increased from 2011 to 2019.The coverage area of U.prolifera disaster reached the peak on June 21,2015,which was about 1714.21 km~2.Afterwards,the coverage area of U.prolifera began to decrease,but the affected area did not decrease,but showed an increasing trend.The monitoring results show that the U.prolifera disaster generally appears in the shallow coastal areas of Jiangsu Province in the middle and late May,and then rapidly grows and propagates and begins to drift to the south of Shandong Peninsula.Finally,it will drift to the south coastal areas of Yantai and Weihai on a large scale and enter the extinction stage.(3)The correlation between the change of the intensity of human activities in the coastal zone and the red tide disaster is mainly reflected in the different types of land cover pollution caused by the nearshore terrestrial human activities.The terrestrial land use types with strong correlation are water area(R=0.807)and structures(R=0.786).However,the disaster of U.prolifera in the southern sea area of Yantai city is caused by the drifting of U.prolifera on the Porphyra culture valve rack in Jiangsu shoal,which has little relationship with the change of human activity intensity in the coastal zone of Yantai,and its growth and reproduction will directly affect the change of seawater quality index,and then affect the coastal human activities.