Study On The Structure Of Marine Fishery Community And Its Niche And Interspecific Association In The East Of Nanji Islands

According to the November 2017 and April 2018 waters in the east of Nanji Islands of fishery resources survey data obtained,using biological index of relative importance index?IRI?,abundance biomass comparing curve?ABC?sort multidimensional scaling?NMDS?clustering analysis niche breadth and some methods such as correlation coefficient???,number of fishery biological species composition in the area distribution characteristics of species diversity ecological niche and interspecific associativity are studied,analyzed the species spatial change of community structure relations and the ecological relationship between the succession of kinds of results show:?1?The catches obtained from the survey,through analysis,a total of 96 species of fishery biological species in the sea area on the east side of Nanji Islands were identified,belonging to 17 orders,49 families,and 73 genera.Among them,there are 48 species in spring,belonging to 43 families and 15 genera of 15 orders;80 species in autumn,belonging to 60 genera,39 families and 15 orders.The number of species in autumn is much higher than that in spring,showing a large difference.In terms of dominant species,fish was the first dominant species in both seasons.Spring includes Scomber japonicus,Odontamblyopus rubicundus,Portunus trituberculatus,Oratosquilla oratoria,Trachurus japonicus,Chelidonichthys kumu and There are 7 species of Thrissa kammakensis;in the fall,there are only 4 species of Harpodon nehereus,Portunus trituberculatus,Oratosquilla oratoria and Benthosema pterotum.The biomass and abundance of fishery organisms in the surveyed sea areas were significantly higher in autumn than in spring.?2?The weight density of this sea area was 244820.2g·km^-22 1231080.9g·km^-22 in spring and autumn,and the mantissa density was 61557ind·km^-22 126241ind·km^-2.The density of fishery biological resources in the surveyed sea area in autumn was much higher than that in spring,and the mantissa density difference was nearly 2 times Spring south quantities distribuion of the east sea area on the spatial distribution of the number of species near south quantities distribuion of stance on one side of the reef species abundance,anaverage of 18 kinds,at the same time in the survey sea southwest and northwest reach maximum densities,and the minimum appeared in 11 stance and station are from the south quantities distribuion,located in the northeast corner of the sea fall survey sea area the number of species distribution more uniform,stood an average 35 kinds.?3?By calculating the biodiversity index,the spring and autumn richness index values are 2.03 and 3.16,respectively.It can be seen that the biodiversity in spring is lower than that in autumn.In specific group comparisons,the biodiversity of fish and crustaceans is higher than that of shrimp and cephalopods.Hierarchical clustering analysis shows that fishery organisms in this area have obvious classification.We can use two-dimensional scale sorting to divide the fishery organisms in the sea area on the east side of Nanji Islands into four groups,and there are differences in the composition of each group.Comparing the results of the study with historical data in this area,it can be seen that with the impact of marine engineering and human activities,the number of species is decreasing and the community structure has also changed accordingly.Abundance biomass comparing curve?ABC?,according to the statistics of W value of 0.045 in the spring,autumn is 0.001biomass curve starting point compared with abundance starting point,the spring abundance curve starting point higher than that of biomass,and autumn beginning almost overlap,thus,the spring is given priority to with small individual in fisheries biology and their difference is small,the weight of the autumn fisheries biology individuals more than spring.?4?Among the 12 stations established by the survey of fisheries resources at the bottom of the trawl,we compared and screened the fishery organisms that appeared in both spring and autumn voyages,and obtained 30 major fishery organisms.The dominant species are three types of Harpodon nehereus,Portunus trituberculatus,and Oratosquilla oratoria,which have a wide niche width.Using niche breadth clustering analysis,the main fishery organisms can be divided into three categories,namely,broad-niche species,meso-niche species,and narrow-niche species.The niche overlap value distribution interval is[0,0.98],indicating that there are differences in the similarity of species'use of resources,and the niche differentiation and accompanying species competition.According to the variance ratio and W test,it was concluded that there was a significant positive correlationamong the main fishery organisms.The test results show that there are 76 species pairs??²?3.841?with significant association,which is related to the community structure stability and species coexistence.The test results of association coefficient?AC?,co-occurrence percentage?PC?and point correlation coefficient???showed that the association between species was strong,and the overall performance was positive correlation.