Spatial And Temporal Variations Of Macro-invertebrate Community Structure And Diversity In Haizhou Bay And Adjacent Waters

Haizhou Bay, a shallow open coastal bay in the western Yellow sea, was ever animportant spawning ground, nursing ground for many commercially important marineliving resources and one of the important fishing grounds. Macro-invertebrate is animportant part in marine ecosystems, and it is indispensable in circulation ofsubstances and flows of energy in the ecosystems of Haizhou Bay. Studies on themacro-invertebrate community structure and diversity in Haizhou Bay and adjacentwater are essential to the deeply understand the variation in fishery resources andsustainable utilization and management of macro-invertebrate resources.In this study, based on data collected from a bottom trawl survey in March, May,July, September, and December2011, temporal and spatial variations of themacro-invertebrate species composition, community stucture and diversity wereexamined, and the effects of ecological factors on the community structures anddiversity in Haizhou Bay were evaluated. Structure of macro-invetebrate communityand its affecting factors were examined using multivariate statistics analysis includingcluster analysis and non-metric multidimensional scaling methods. The diversity ofmacro-invertebrate community and its affecting factors were examined usingecological diversity indices and generalized additive models (GAMs).There were72macro-invertebrate species collected, belonging to2classes,5orders,28families and53genera. Brachyuras (37taxa,51.4%of the total number ofspecies) were the most abundant taxonomic group in the macro-invertebrate taxa, andcephalopods (7taxa,9.7%) were in the last place.27taxa (37.5%) caught in thesurveys were Decapodas. There were no significant temporal differences in taxonomic group compositions (P>0.05). Determined by IRI, the dominant species of themacro-invertebrate community were Metapenaeopsis dalei and Alpheus japonicas inMarch; M. dalei, Loligo sp. and Crangon affinis in May; only M. dalei in July; loligosp., Charybdis japonica and Trachypenaeus curvirostris in September; M. dalei, T.curvirostris, Octopus ocellatus, loligo sp. and Charybdis bimaculata in December.Margalef species richness index d, Pielou evenness index J’ andShannon-Wiener diversity index H’ was calculated and diversity contour maps wereplotted. There were distinct seasonal variations in the spatial distribution of themacro-invertebrate community diversity. Northwest coastal and southern waters ofHaizhou Bay and adjacent waters were the areas with high H’, and northeasternwaters were of the low value of H’ excepte in winter, and the same as d and J’. The H’values of the areas with a high abundance of the dominant species were lower thanthose in other areas.GAM was used to relate H’ to a readily measured or computed variables,including bottom water temperatures, salinity, month, latitude, longitude and chla. TheGAM in this part included bottom water temperatures, salinity, month, latitude andchla in total explained49.79%of the deviance of Shannon-Wiener diversity index H’.Month exerted the strongest effects of any individual variable, and it explained18.46%of the deviance of H’. Relatively high bottom water temperatures wereassociated high value of H’, and it explained9.45%of the deviance of H’. Latitude,salinity and chla also had close relationships with H’, and they explained8.75%,7.02%and6.11%of the deviance of H’, respectively.The analysis of multivariate methods showed that three community groups(station group) were identified for macro-invertebrate community in Haizhou Bay andadjacent waters: Northeastern and northern waters community group I; Coastal andoffshore community group II; Southern waters community group III. One-wayanalysis of similarity (ANOSIM) indicated that there were significant differences incommunity species compositions among different community groups in four seasonsurveys. The typifying species in each station groups were also the discriminatingspecies in different station groups, most of which were the dominant species in each station groups as well. The variations of relative biomass and abundance of thesespecies led to the discrimination between different station groups.BIOENV analysis illustrated that water temperature, salinity, depth of water,dissolved oxygen (DO), pH and their combinations were related with structure ofmacro-invertebrate community in Haizhou Bay and adjacent waters. The distinctionof above environmental factors affected by different water masses and currentsresulted in different spatial pattern of macro-invertebrate communities in HaizhouBay and adjacent waters.