Community Structure And Diversity Of Fish In The Sea Area Of Nanji Islands

Studies on biodiversity status of fishery community in sea area of Nanji islands.Based on the data fishery resources from the four seasons trawl survey in sea area of Nanji islands during November 2013 to September 2014.This paper discussed the charzcteristics of fish community structure,species dominancy and diversity.The results are as follows:(1)A total of 102 species were identified which were consisted of 5 species of Chondrichthyes fish and 97 species of Osteichthyes fish.Chondrichthyes fish and Osteichthyes fish were respectively account for 4.90% and 95.1% of the total number of species of fish.The most species-rich orders were Perciformes(51 species),next was Clupeitormes(9species).The number of species in different seasons respectively were Spring(58 species)>Winter(55 species)>autumn(51 species)>Summer(42 species).There were 19 common species in four seasons.There were only warm-water species and warm-temperate species.And warm-water species were dominant.Through the analysis of the Index of Relative Importance(IRI)showed that there had no dominant fish species in one year around,also had no dominant fish species in three seasons.There were 3 fish species were dominant species in two seasons,and 4 fish species were dominant species in single season.And the succession of dominant species between different seasons was obvious.The average biomass and average abundance were highest in summer.The average biomass was lowest in spring,and the average abundance was lowest in autumn.(2)The value of Shannon-Weaver index(H')was highest in Autumn,Spring took second place,and it was lowest in Summer.The value of Pielou index(J')was closely in four seasons;it was highest in autumn and lowest in spring.The value of Margalef index(D)varies greatly,and the value in spring was absolute higher than other seasons.(3)According to the NMDS analysis,2 d scale sequence diagram had a certain meaning interpretation in four seasons.CLUSTER analysis showed that autumn and winter had 3 different community groups,spring and summer had 2 different community groups.ANOSIM analysis showed that there had obvious difference in part of community groups,and in part of community groups had little difference.SIMPER analysis showed that the average similarity in different group of every season was low.The average dissimilarity of fish group was highest between summer and autumn,and it is lowest between winter and spring.