Analysis Of The Food Network Structure Of Oriental White Stork In Xingkai Lake

The conservation of endangered species is a hot issue in ecological research.A stable food web structure is vital to the survival and reproduction of the oriental white stork(Ciconia boyciana),an endangered species,which is of great significance to maintain species diversity in the ecosystem.Starting with the stability of the food web,this study aims to provide a clearer goal for the protection of the oriental white stork and a more novel idea for protecting endangered species,by quantitatively constructing the food web structure model of the oriental white stork using C and N stable isotope technology,and introducing the complex network centrality theory to identify the key species in the food web.In this study,fish samples and feather samples of fledglings of the oriental white stork were collected in Xingkai Lake area in 2018.On the one hand,the nutrient levels of each species were calculated through the analysis of C and N stable isotopes of the samples,and the SIAR(stable isotope analysis in R)in R software was used to quantitatively construct the food web structure model of the oriental white stork,so as to analyze the feeding habits of its fledglings.On the other hand,based on the complex network centrality theory,we ranked the centrality of complex networks under different indicators and analyzed the correlation and differences of centrality of different complex networks by treating the food web structure model of the oriental white stork as a directed-weighted network and calculating the degree centrality,closeness centrality,betweenness centrality and PageRank centrality of each node in the network.The results are as follows.1)There were significant differences in ?13 and ?15N among the species in the food web of the oriental white stork in Xingkai Lake area.The trophic level of each species ranged from 2 to 3.88.According to the diet,each species is divided into four trophic groups.The trophic level of primary consumers ranging from 2 to 3.15,with a span of 1.15;the trophic level of secondary consumers ranging from 2.98 to 3.32,with a span of 0.34;the trophic level of intermediate consumers ranging from 3.15 to 3.63,with a span of 0.48;the trophic level of senior consumers ranging from 3.64-3.88 with a span of 0.48.In general,the width of trophic level of the oriental white stork's food web was narrow,with the carnivorous fish Erythroculter ilishaeformis at the top of the food chain.2)Primary consumers were the main energy source of Oriental white stork's food web.The average contribution rate of Leander modestus to its predators was the highest(41.35%),followed by snails(30.61%)and loach(24.43%).Primary consumers had a high contribution rate in the food web,which was the basis of the structure of food web.it is believed that Leander modestus is the key species in the food web of the oriental white stork in Xingkai Lake.3)Although there were differences in the results of degree centrality,closeness centrality,betweenness centrality and PageRank centrality,the centrality results all showed that Leander modestus was the key species in the food web of the oriental white stork.4)Erythroculter ilishaeformis had the highest contribution rate(25.17%)as a food source of the oriental white stork;the lowest was Leander modestus(1.29%),while the average food contribution rate of shrimp was only 3.3%.nestling of the oriental white stork in the breeding ground primarily fed on fish(93.94%).In this study,key species in the food web was determined by constructing a quantitative food web model of the oriental white stork and calculating the critical degree of each species in the food web under multiple indicators.Through analyzing the structure of the food web,we could not only offer data for the wetland food web,but also provide important theoretical support for formulating policies for the protection of endangered species and making clear the direction of our protection efforts.