Temporal And Spatial Variations Of The Fish Community Structure In Haizhou Bay And Adjacent Waters

Based on the data collected from the bottom trawl survey in Haizhou Bay andadjacent waters in March,May,July,September and December2011, the area typesand species composition,temporal and spatial variations of quantity variations,dominant species and species diversity were studied in this paper. Cluster analysis andnon-metric multidimensional scaling were used to study the spatial pattern of fishcommunity, and its relationship with environmental factors was discussed usingcanonical correspondence analysis.The main results of this study are listed as follows:1. A total of89fish species were captured from the surveys, belonging to74genera,46families and12orders, besides Raja porosa was cartilaginous fish, theremaining species were bony fishes. There were45warm temperate fishes accountingfor50.56%of the total number of fish species occurred,31warm water fishesoccupying34.83%, and13cold temperate fishes amounting to14.61%. There were72bottom fish species amounting to80.90%, and pelagic fish species accounting for19.10%of the total number of fish species. The number of different ecological fishshowed different variations with time.2. The mean relative resources changed significantly in each month. The meanrelative biomass was10744.32g/h, varied from2648.95to19240.14g/h, the meanrelative abundance was1743.88ind/h, varied from588.80to3198.80ind/h in theperiod of the surveys, which was the lowest in March and the highest in July.3. The composition of dominant species and their numbers were different in eachsurvey. The numbers of dominant species ranged from4to9differently and there wasa certain variation of dominant composition. The cold temperate species weredominant in spring, the warm water and warm temperate species began to dominate insummer and autumn gradually and the warm temperate species were dominant inDecember. Pholis fangi and Syngnathus acus became the dominant species4times in the surveys.4. The number of species, Margalef species richness index, Shannon diversityindex and Pielou evenness index ranged from41(March) to64(September),4.66(May) to6.94(September),2.47(March) to2.90(December), and0.63(May) to0.71(December) respectively with time. Except the Pielou evenness index, the number ofspecies, Margalef species richness index and Shannon diversity index showed thedistribution trends which were low in the external waters and high in inshore watersentirely. But these distribution trends in December were just contrary to other months.Correlation analysis of community diversity index and environmental factorsindicated that water temperature and water depth were the most importantenvironmental variables having impact on the spatial patterns of community diversityindex.5. Cluster analysis and non-metric multidimensional scaling (MDS) analysisshowed that the fish communities in Haizhou Bay and adjacent waters could beclustered into four station groups: the northeast fish community in the deep waters(group I of five surveys), fish community in inshore waters near bay-head (group II ofDecember), southern fish community (group III of March and December, group II ofSeptember)，mixed fish community (group II of May, including fish community ininshore waters near bay-head and southern fish community). ANOSIM analysisshowed that there existed highly significant differences (R=0.45—0.99, P<0.01)among different station groups and between pairwise comparisons in Haizhou Bayfish community.6. The canonical correspondence analysis (CCA) showed that the bottom watertemperature and water depth were the most important environmental variablesaffecting the spatial pattern of fish community in Haizhou Bay and adjacent waters,while the salinity also had some influence on spatial distribution of the fishcommunity.