Study On Seasonal Variations Of Community Structure Of Fishery In Rushan Bay And Its Adjacent Waters

This research is based on the data of the samples collected from two surveys inRushan Bay and adjacent waters in spring (May,2010) and autumn (October,2010),analyzing the species composition, key species,, biomass, biodiversity and ABC curveof the fishery there and the relative environmental factors. This paper summarize thefishery community structure in Rushan Bay and adjacent waters, study the connectionbetween the fluctuation of fishery and the environmental factors, analyze some maineconomic fishes and bring forward some suggestion about how to manage andmaintain the fishery resources in Rushan Bay and adjacent waters. The situations inthe two seasons are compared to table a proposal for protecting the fishery resource inRushan Bay and its adjacent waters.The main results of this research are as follows:1. A total of69species of fishery were collected from the research region in the twocruises, including Osteichthyes (31)，Crustacea (18)，Mollusca (16)，Coelenterata (1),Echinodermata（3）.There are altogether32common species in the two cruises. Ofwhich13species are identified as the dominant species in the research region in twocruises, including Osteichthyes (5), Crustacea (5), Mollusca(3).Alpheus japonicusand Oratosquilla oratoria are common dominant species in both of the two cruises.2. The average biomass of the two cruises is343.88kg/km~2, and those of the fivesampling stations are: R5>R1>R3>R2>R4. The biomass range from spring to autumnis313.36～374.40kg/km~2, and the range of sampling stations is from247.82～556.02kg/km~2. The average abundance of the two cruises in Rushan Bay and its adjacentwaters is76614.09ind./km~2, the range from spring to autumn is75349.04~77879.13ind./km~2, those of the five sampling stations are: R5>R4>R2>R1>R3. The abundancerange of sampling stations is from32026.19to142293.10ind./km~2, and the averageabundance of spring is lower than that of autumn, the abundance of Osteichthyes inspring and autumn is higher than the rest of the species. 3. Biodiversity indices of fishery in autumn are all higher than those in spring.Whencompared with the Biodiversity indices of fishery outside the Rushan bay,there arehigher index in Shannon-Weiver and Pielou’s evenness index but lower index inMargalef index in Rushan bay.4. The ABC curves of sampling stations and the values of W from most stationsindicate that, compared with adjacent waters, the fishery communities in the researchregion have trends of modest disturbance in Ruanshan bay. The low-level catchingintensity may be the main reason resulting in the smooth disturbance.5. The results of SIMPER analysis showed that the average similarity of communitystructure in two cruises is18.68%and the dominant species (the contribution tosimilarity>5%) are Alpheus japonicus（22%）, Oratosquilla oratoria（14.35%）,Loligo sp（.12.59%）, Palaemon gravie（r12.44%）and Parapenaeopsis tenell（a10.5%）.Multivariate ANOVA analyses confirm that there are significant differences in thespecial environmental factors among the two cruises. The results of RELATE analysisamong the two cruises show that the environmental factors is significantly correlatedwith the community structure of fishery. BIOENV and BVSTEP(Spearman) resultsimply that ph value、chemical oxygen demand and dissolved oxygen can affect thecommunity of fishery significantly while the biomass is mainly influenced by thetemperature, salinity, chemical oxygen demand，dissolved oxygen and Hg。Correlation(Pearson) analyses reveal that chemical oxygen demand，dissolved oxygen，Hg，thesalinity and suspended solids are most closely related to the biodiversity.