The Macrobenthic Community Structures In The Yellow Sea And The Bohai Sea

In the present study, the macrobenthic species composition, abundance, biomass,diversity and community structure of were analyzed using the macrobenthic data ofJun.13~Jun.30,2011(summer cruise), Nov.24~Dec.6,2011(winter cruise) andMay.5~May.20,2012(spring cruise), together with the environmental factors in theYellow Sea and the Bohai Sea (31°N-40°N,120°E-124°E). The seasonal and largescale spatial variations of macrobenthos were exhibited in our study. Meanwhile, thespatial variations of macrobenthos were analyzed in this paper using the biologicaldata of Laizhou Bay (Jun.1~Jun.4) and Daya Bay (Aug.29~Sep.1).(1) Macrobenthos in the Yellow Sea and the Bohai Sea.119species were identified in spring,120in summer and101in winter. Thesespecies belonged to eight phyla: Cnidaria, Nemertea, Annelida, Echiura, Mollusca,Arthropoda, Chaetognatha and Echinodermata. Annelida, Mollusca and Arthropodacontributed most to the species composition.The mean abundance in spring was227ind/m2,430ind/m2in summer and94ind/m2in winter. The mean abundance was higher in summer and lower in winter. Theabundance was higher in waters near the Shandong and Liaodong Peninsula and in thecenter of cold water mass of the North Yellow Sea. Thyasira okunagai, Sternaspiscutata, Ampelisca bocki and Paralacydonia paradoxa were the dominant species inthe three seasons.The mean biomass in spring was14.7g.wwt/m2,21.9g.wwt/m2in summer and16.3g.wwt/m2in winter. The mean biomass was the highest in summer and lowest inspring, this might be due to the occurrence of more juveniles which were smaller inbody size. The mean biomass did not show obvious differences among different seaarea. Species of Echinodermata and Mollusca usually exhibited high values of biomass as they were larger in body sizes, and some species of Arthropoda also hadhigh values of biomass as their high abundance.The mean secondary production in Yellow Sea and Bohai Sea was8.087g（AFDW）/(m2.a) in spring,9.412g（AFDW）/(m2.a) in summer. This value wasmuch lower in winter (5.505g（AFDW）/（m2.a）.Species richness index (d) were similar in spring and winter, but lower insummer. The values of d were higher in the Bohai Sea. Species evenness index (J’)were more even in the Yellow Sea (especially the South Yellow Sea) than that in theBohai Sea. Shannon-Wiener diversity (H’) were similar in spring and summer, andthis index was lower in the winter. Taxonomic diversity of the Yellow Sea (especiallythe North Yellow Sea) was below average in spring and winter.Results of two-way ANOVA tests showed that there were no significant areaseason interaction effect for taxonomic diversity and species diversity indexes (exceptspecies evenness index). Species evenness index (J’) and Shannon-Wiener index (H’)showed significant difference between areas. Average taxonomic distinctness (△*)and average taxonomic distinctness based on presence/absence species (△+) weresignificantly different between seasons.The macrobenthos of Yellow Sea and Bohai Sea could be generally grouped intothree communities.Community: Bohai Sea and nearshore community. It was located at the nearshorearea of Shandong and Liaodong peninsula and in the Bohai Sea and the North YellowSea. The abundance and species numbers were high in this community. S. scutata wasdominant in this community.Community Π: Cold water mass community. It was located at the cold water mass ofNorth Yellow Sea with deeper waters. Species were often typical cold water species. T.tokunagaii was dominant in this community.Community Ш: the South Yellow Sea community. It was located in the South YellowSea. Species were often warm water species and mollusks were dominant in thiscommunity.(2) Macrobenthos in the Laizhou Bay and Daya Bay. The mean abundance in Laizhou Bay was higher than that of the Yellow Sea andthe Bohai Sea, but the mean biomass and secondary production were lower. Speciesrichness, species evenness and Shannon-Wiener diversity were all lower in LaizhouBay. This maybe because that the sampling area was concentrated in Laizhou Bay.The species composition of Daya Bay was very different with Laizhou Bay.Arthropoda’s dominant position was taken by Mollusca and warm water species weremore dominant. Its mean abundance was smaller than that of Laizhou Bay, but meanbiomass and secondary production were higher as big-sized species were common inDaya Bay. The macrobenthos in Daya Bay were more diverse than that in LaizhouBay.