Ecology Of Macrobenthic Community In Rushan Bay And Its Adjacent Waters

The ecological characteristics of macrobenthos and some environmental factors in the southern coastal water region of the Shandong Peninsula are approached during the thesis work, based on the material collectiong by the cruises in December 2006, May 2007, August 2007 and November 2007, which represent winter, spring, summer and autumn respectively. The ecological charactors include species number, key species, abundance, biomass, community structure, biodiversity, ABC curve, secondary production of the macrobenthos, and the relative environmental factors. The situations in the four seasons are compared. The software packages of PRIMER 5.0 and SPSS 15.0 are used in the data analysis. The results are compared with those from Jiaozhou Bay. This is the first time to report systematically the macrobenthic community structure from the coastal water off Rushan.The main results of this research are as follows:1. A total of 183 macrobenthic species are collected from the research region by the field works, including Polychaeta (64 species), Mollusca (51), Crustacea (48), Osteichthyes (7), Echinodermata (5), Coelenterata (3), Hemichordate (2), Flatworm(1), Nemertinea (1) and Sipuncula (1). Of which, 33 species are common species by the four cruises. The species numbers presenting in the four cruises are: spring (103 species)>winter (94)>autumn (88)>summer (87).Eleven species are identified as the dominant species in the research region in different cruises in accordance with their dominant values (Y) in different cruises. The polychaete species Nephtys oligobranchia and Sternaspis scutata are always dominant in the four cruises. The ratio of seasonal alternations is winter-spring: 62.50%, spring- summer: 77.78%, summer-autumn: 57.14% and autumn-winter: 57.14%, respectively.2. The average abundance of the four cruises is 238 ind./m2, those of the four cruises are respectively: spring (319 ind./m2)>winter (218 ind./m2)>autumn (217 ind./m2)>summer (201 ind./m2). The average biomass of the four cruises is 104.64 g/m2, those of the four cruises are: summer (229.22 g/m2)>spring (86.10 g/m2)>autumn (60.69 g/m2)> winter (42.54 g/m2).3. The richness indices of the marcobenthos of the four cruises are: spring (3.472)>winter (3.166)>autumn (2.874)>summer (2.864) and the average value is 3.094±0.288. The evenness indices are: winter (0.884)>spring (0.875)>autumn (0.867)>summer (0.866) and the average value is 0.873±0.009. The Shannon-Wiener indices are: spring (2.671)>winter (2.503)>autumn (2.352)> summer (2.293) and the average value is 2.441±0.147. The average values of the above three indices from the stations near to the culture field of Ruditapes philippinarum are the lowest.4. The average secondary production of the research region is 8.44 g/(m2·a) in which Ruditapes philippinarum contributes the highest 5.60 g/(m2·a) among all the macrobenthic species. The average P/B value is 0.45, means that one life circle of most species in the macrobenthos of the research area needs about two years.5. The ABC curves of four cruises and the values of W from most stations indicate that the macrobenthic communities in the research region has not been disturbed distinctly in addition to few stations, which have trends of modest disturbance. The sediment type may be the reason resulting in the disturbance.6. The results of SIMPER analysis shows that the average similarity of community structure is 28.24% and the dominant species (the contribution to similarity >5%) are Nephtys oligobranchia(19.62%), Mediomastus californiensis(8.60%), Sternaspis scutata(8.34%) and Heteromastus filiformis (7.41%). One-Way ANOSIM test of four cruises reveals significant differences both globally and for pairwise test between seasons of which the autumn-winter pair has the highest average dissimilarity value, contributed by the following main species (the average dissimilarity >2%): Eocylichna cylindrella (2.77%), Mediomastus californiensis (2.53%), Theora lubrica (2.43%), Nephtys oligobranchia (2.35%), Ampelisca cyclops (2.23%) and Sternaspis scutata (2.19%).7. Multivariate ANOVA analyses confirm that there are significant differences in the special environmental factors among the four cruises. BIOENV and BVSTEP (Spearman) results imply that the temperature, salinity, nutritive salt and the content of silt in sediment affect the macrobenthic community significantly while. the biomass is mainly influenced by salinity, nutritive salt, the sedimental concentrations of heavy metal As. Correlation (Pearson) analyses reveal that the salinity, nutritive salt, temperature and the sedimental concentrations of heavy metal Zn are closely related to the biodiversity whereas the total alkalinity, salinity and nutritive salt to secondary production of macrobenthos.8. In comparison with the macrobenthic community of Jiaozhou Bay, the ecosystem of research region seems more stable while the shellfish culture still affects the community structure more or less.The conclusions are expected to be as an important reference in the exploiting of Rushan Bay and as well for the social and economic acquirement in long term.