The Study On Macrobenthos By Bottom Trawling In The North Yellow Sea

The systematical research has been carried out based on the composition and distribution of species,quantity variations,biodiversity and community structure of macrobenthos mainly from the date of surveys of 4 cruises from July 2006 to October 2007 in the North Yellow Sea.The samples were collected by bottom trawling.Major conclusions from the research are the below:1. It was of stablization of the composition of macrofauna in North Yellow Sea, especially for the one in winter and spring. Great disparity of replacing rate between seasons in different macrofaustic groups was observed. Among all macrofaustic groups, the greatest flucutation of species compostion was observed in fish group and the average replacing rate between seasons was the greatest one.2. Horizontal distribution of dominant species: The cold water and high salinity species, Ophiura sarsi was absolute dominant in the deep water area.In the coastal waters richness of species composition and dominance was not obvious. The subrogation rate of fish is, the largest. That of Echinoderms, is the smallest. Total subrogation rate of dominant species is steady.3. During the surveys, mean catch per haul in Spring was the highest, in Summer was the second highest,in Winter was the third and in Autumn the lowest。It was lower in the coastal of LiaoDong Peninsula and ShanDong Peninsula。analysis showed that the distribution of mean catch per haul and water depth was very significant positive correlation.4.Coelenterate(main specie was Metridium sensile fimbriatum) was more than two groups Crustaceans and Mollusc in the contribution of the mean catch per haul. Trawl surveys at the end of the previous rare reports on the Coelenterate, tolerance ability as a result of sea Actiniaria, so fouling organisms commonly found in the investigation report, the North Yellow Sea captured a large number of Actiniaria may be a signal change in the marine environment.5.The overall index of biodiversity characteristics is on the low side. Inshore is higher than deep sea area in the horizontal distribution of biodiversity. individual stations' index of biodiversity significant variations were observed in different seasons,resulting in overlapping community structure.6.According to the CLUSTER and MDS analysis, three assemblages of macrobenthos were classifed: Assemblage 1: Crangon affinis- Luidia quinaria- Carcinoplax vestitus, Assemblages 2: Ophiura sarsi - Metridium Oregonia gracilis, Assemblages 3: Acila mirabilis- Ophiura sarsi - Cancer gibbosulus.