Systematic Conservation Planning Research Based On The Characteristics Of Aquatic Resources In The Yangtze Estuary

The Yangtze Estuary is the largest estuary in China,with a unique ecosystem and rich aquatic biological resources,but in recent years the aquatic biological resources have continued to decline,and the conservation of aquatic biological resources has become an urgent priority.In order to conserve aquatic biological resources,a ten-year fishing ban has been implemented in the Yangtze River since 2020,and the scope of the fishing ban in the Yangtze estuary has been expanded to restore aquatic biological resources.Based on the monitoring survey of aquatic biological resources in the Yangtze River estuary from 2017 to 2021,this study summarizes and analyses the distribution characteristics of aquatic biological resources,uses a systematic conservation planning approach,explores conservation planning based on different objectives,and identifies priority areas for conservation.The results are as follows.(1)This study analyzed the distribution characteristics of aquatic biological resources in the Yangtze River estuary from 2017-2021,and the results showed that there were 21 species of aquatic biological resources in 6 orders,11 families and 19 genera of fish,10 species of crabs in 1 order,5 families and 7 genera,and 9 species of shrimps in 1 order,3 families and 5 genera in the Yangtze River estuary.The overall aquatic life resources distribution characteristics are obvious,the resource density of the northern branch of the Yangtze River estuary is greater than that of the southern branch waters,and the external waters of the east beach of Chongming Island are greater than that of the inner estuary of the Yangtze River estuary.2017,2018 and 2019 have similar overall resources,6400ind/h,7564ind/h and 4088ind/h respectively.2020 has a greater increase in resources than the previous three years,at The resources of Z5 and Z16 sampling sites are above 1400ind/h,and the distribution of aquatic high resource areas in the Yangtze estuary is more concentrated.(2)Systematic conservation planning was carried out by Marxan,from the overall resource distribution characteristics,different conservation grid scales were set,and the characteristics of each conservation scheme were compared under different degrees of conservation.The results are as follows: when the degree of conservation changes,there is a common trend of change for all specifications of planning cells.Taking the planning cell of 3km×3km specification as an example,the number of planning cells selected by high frequency(80～100)at 25% of the representative target is obtained to be the least,16;at 30% of the representative target,the number of planning cells selected by high frequency In other words,the higher the representative target,the more planning units are selected with high frequency and the higher the irreplaceability of the conservation solution.The planning units selected in the optimal solution also gradually become more and more concentrated in the east-west monitoring section of the north port of the south branch of the Yangtze River estuary and the external waters of the east beach of Chongming Island at 122°10′E.The distribution range of the planning units in the inner estuary expands to the west,and the planning units in the external waters of the east beach of Chongming Island gradually form a connection with the waters of the north branch of the Yangtze River estuary and expand to the west at the same time.The scope of protection is more connected and the degree of protection is more extensive,but the cost of protection is higher.For the same level of protection,planning units of different specifications change in different ways.Taking the 25% representative target as an example,in the 3km x3 km planning unit there are only 14 high-frequency planning units,accounting for 7%of all selected planning units.However,in the 5km x 5km planning unit there are 23high-frequency planning units,representing 24% of the total number of planning units selected.In the 10km×10km planning unit there are 21 high-frequency planning units,accounting for 51% of the total.The higher the percentage of planning units selected with high frequency,the higher the percentage of planning units selected with high frequency and the corresponding increase in the number of planning units selected in the optimal solution,which may be correlated with the distribution of species resources in the larger planning units.This may be related to the fact that larger planning units contain more species distribution features.(3)Systematic conservation planning sets a relatively high conservation urgency index to protect key aquatic organisms,and this index can have a large impact on the results of systematic conservation planning.In order to study the influence of this index on the planning,different conservation urgency indices were set,and the results were as follows: when the urgency conservation index was set for the key aquatic organisms,the system conservation planning gave a wider range of conservation programs and tighter connectivity.This is shown by the number of planning units selected in the optimal solution under the 25% representative target,for example,72 planning units were selected in the optimal solution with the introduction of the conservation urgency index,and only 39 were not introduced,and close to 50% of the planning units were not selected in both numbers.The number of planning units in the high frequency selection and optimal solution when the index is introduced is much larger than the number without the index,indicating that the index can influence the irreplaceability of key protected aquatic organisms,priority conservation areas and changes in conservation vacancies to a greater extent,so it can be concluded that it has a certain effect on the conservation of key protected aquatic organisms in systematic conservation planning.In this study,based on the characteristics of aquatic resources in the Yangtze River estuary,a series of conservation scenarios were proposed for the Yangtze River estuary using a systematic conservation planning approach,and the role of conservation urgency index on priority aquatic organisms was investigated through controlled analysis.An exploratory study on the conservation options of different targets in the Yangtze estuary is provided.In this study,based on the characteristics of aquatic resources in the Yangtze River estuary,a series of conservation scenarios were proposed for the Yangtze River estuary using a systematic conservation planning approach,and the role of the conservation urgency index on priority aquatic organisms was investigated through controlled analysis.An exploratory study on the conservation options of different targets in the Yangtze estuary is provided.Meanwhile,this study has some reference significance for the conservation of aquatic resources and ecological civilization construction in the Yangtze Estuary.