The Ecological Study Of Macrobenthos In North Yellow Sea In Spring And Autumn

According to the investigations in North Yellow Sea in May,2007(spring cruise) and Oct.,2007(autumn cruise). The macrobenthic species composition, abundance, biomass, biodiversities, and community structure were analyzed. The secondary production and Taxonomic Distinctness of macrobenthos in North Yellow Sea were caculated for the first time.1. In spring,332 species were identified, in autumn, it was 315. These species belong to Coelenterata, Nemertinea, Annelida, Echiura, Sipuncula, Mollusca, Arthropoda, Brachiopoda, Bryozoa, Echinodermata, Hemichordta and Chordata. Annelida contributed most to the species composition.2. The total mean abundance in spring was 1130 ind./m2, ranged from 30 to 4095 ind./m2. In autumn, it was 830 ind./m2, ranged from 25 to 2495 ind./m2. The distributions of abundance were similar in two seasons. The abundance was higher in Liaodong coastal water, east of Bohai Strait and the center of cold water mass. It is lower in the east of North Yellow Sea. Annelidas were the dominant group in both cruise.3. The total mean biomass in spring was 65.04g.wwt/m2, ranged from 0.33 to 1117.95g.wwt/m2. In autumn, it was 50.60 g.wwt/m2, ranged from 0.40 to 394.27 g.wwt/m2. Echinodermatas were dominant group in both cruise. The centre of cold water mass had higher biomass. 4.The dominant species in spring were:Thyasira (Thyasira) tokunagai, Ophiura sarsi, Eudorella pacifica and Sternaspis scutata.The dominant species in autumn were:T. tokunagai,O. sarsi, S. scutata and Nereis longior. T.tokunagai and O. sarsi distributed in centre of the cold water mass, they were the most important dominant species of North Yellow Sea.5.The secondary production of macrobenthos in North Yellow Sea was 7.596 g (AFDW)/(m2.a), P/B was 0.912. O.sarsi and T.tokunagai contributed most to the secondary production.6. The macrobenthos of North Yellow Sea can be grouped into 3 communities. Communityâ… :offshore community. It was located at offshore area of shandong and liaodong peninsula. It was influenced by the terrigenous climate and anthropogenic activities, and composed mainly of widespread species. The species numbers, abundance and biodiversities were high in this community. Communityâ…¡:cold water community. It was located at the cold water mass. It had the lowest bottom temperature and highest bottom salinity, toc, biomass, secondary production and P/B among 3 communities. Communityâ…¢:sandy sediment community. This community was found in medium to course sediment in the east of North Yellow Sea, with lowest toc, abundance, and biodiversity. Comparing with historical data:the community structure had changed in recent fifty years:dominant species in offshore areas became polychaetes instead of echinoderms and arthropods, the range of cold-water community diminished about half longitude.7. The mean Taxonomic Distinctness in spring is 84.96. Communityâ…¡had the highest value,88.86. Different from Taxonomic Distinctness, Shannon-Wiener is highest in community I, lowest in communityâ…¡.