Habitat Evaluation Of Yangtze Finless Porpoise Provincial Nature Reserve In Zhenjiang

With good water quality,abundant fish resources,little human interference and superior natural environment,the provincial nature reserve of Yangtze finless porpoise in Zhenjiang,Jiangsu Province is a good place for Yangtze finless porpoise(Neophena asiaeorientalis)and other aquatic wild animals to live and care their young.With the development of local economy and the opening of deep-water waterways,the habitat characteristics of the reserve have changed to some extent,which may have a certain impact on the Yangtze finless porpoise.Therefore,it is particularly important to carry out ecological research on the habitat of the Yangtze finless porpoise,evaluate its suitability,and provide scientific basis for the management of the reserve.In order to understand the distribution and population quantity of the finless porpoise in the Nature Reserve,the transversal sampling method was used to conduct scientific investigation of the finless porpoise in three different water periods.In order to explore the key factors affecting the distribution characteristics and activity patterns of the finless porpoise in the reserve,the water environment indexes and fish and other aquatic biological resources were investigated simultaneously,and the correlation analysis was conducted based on the distribution characteristics of the finless porpoise.Finally,Eco Path habitat evaluation model was used to evaluate the habitat status of Zhenjiang Yangtze finless porpoise provincial nature reserve,so as to provide a theoretical basis for habitat protection.The experimental results are as follows:1.According to the comprehensive analysis of annual data,the population of the Yangtze finless porpoise in the reserve will be about 20 in 2020.The distribution of finless porpoises was mainly in groups(≥2)and near shore(≤500 m from shore),mainly concentrated in the beachhead area of Jiaobeitan,the northeast corner of Hechangzhou and the area in the east of it.2.The annual TLI of water was 51.647±6.074,and the water was slightly eutrophication;A total of 6 phyla,49 genera and 79 species were collected and identified.The density and biomass were 9.26×10~5cells/L and 0.29 mg/L,respectively,and the genus Pseudanabaena sp.Was the most dominant.A total of 32 species of four species were collected and identified,and the density and biomass were 119.19 ind./L and 0.04 mg/L,respectively.Tintinnidium entzii was the dominant species.A total of 26 species,17 genera and 4 phyla,were collected and identified,and the density and biomass were 184.44ind./m~2and 0.41 g/m~2,respectively.Teneridrilus mastix was the dominant species.3.A total of 51 species of 15 orders,8 families were collected and identified,including 5 dominant species.They were Parabramis pekinensis,Coilia nasus,Pelteobaggrus nitidus,Hypophthalmichthys molitrix and Aristichthys Nobilis.According to the ecological types,omnivorous fish,bottom fish and freshwater sedentary fish are dominant.The annual survey of the reserve showed that the fish community diversity index was at a high level,and the results were successively:Margalef index(R)was 7.76,Shannon-Wiener index(H’)was 2.80,Dominant index(J)was 0.70,and Pielou index(D)was 0.10.In terms of spatial characteristics,the Dominant index(J)and Pielou index(D)have significant differences between different sections(p<0.05).In terms of time characteristics,there was no significant difference in fish community diversity index(p>0.05).4.The main factors affecting the activities of the finless porpoise in the waters of the Nature Reserve were vessel navigation,phytoplankton biomass and hydrological conditions,which showed that the finless porpoise was mainly distributed at the head and tail of the river core,meandering river reaches and the confluence of multiple streams.However,the effect of water quality on finless porpoise was not obvious.5.Based on the Ecopath model to reserve the Yangtze finless porpoise habitat quality analysis and evaluation,reserve functional group scores trophic level range 1.000-2.795,trophic level to the highest species in reserve for the Yangtze finless porpoise,reserve ecosystem energy source for phytoplankton and debris,energy flow are two ways to have pastoral food chain and food chains.Among them,the energy from primary producers accounted for 60.00%of the total energy flow,and the energy from organic debris accounted for 40.00%of the total energy flow.The ratio of total primary production to total respiration(TPP/TR)was 4.754,and the ecosystem connectivity coefficient(CI)of the reserve was 0.321.The Finn circulation index(FCI)of the reserve was 1.818%.The characteristics show that the ecosystem of the reserve is still in the immature state,the food web links are not stable,the nutrient structure is simple,and the material recycling ability is low.