Preliminary Study Of Functional Groups And Ecological Study Of Macrofauna In Jiaozhou Bay

To study the ecological characteristics of macrofauna especially for the functional groups and their relationships with environmental factors in Jiaozhou Bay, and to provide the scientific basis for sustainable use of marine biological resources and ecosystem health evaluation, macrofauna samples as well as environmental factors were collected at 14 stations in February, May, August, and November,2014. A quantitative study of macrofauna in Jiaozhou Bay was conducted, including abundance and biomass, species composition and community structure, biodiversity, and secondary production. The functional groups of macrofauna was also studied, and the relationships of macrofauna and environmental factors were analyzed by using multianalysis.A total of 251 species were collected during the 4 cruises, including 104 species of Polychaeta,73 species of Crustacea,51 species of Mollusca,11 species of Echinodermata, and 12 species of other taxa. The average abundance was 2525.50 ind./m2, and the average biomass was 158.79 g/m2. The dominant groups were Polychaeta, Crustacea, and Mollusca. Compared with the historical data, and the proportion of each taxa were similar, which indicated that the taxa composition of the macrofauna in Jiaozhou Bay was very stable within the latest 30 years. The spatial distribution pattern of macrofaunal abundance was a little different with biomass in the 4 cruises. The highest biomass value was found in autumn, intermediate in summer and spring, and the lowest in winter, while the abundance value in spring was higher than that in summer. Compared with the historical data, the abundance was higher than the historical data of Jiaozhou Bay and the adjacent sea. which could due to a great quantity of Hemileucon bidentatus and Ruditapes philippinarum were collected in this research. Based on Pearson correlation analysis, the abundance of macrofauna had a significant positive relationship with bottom water temperature while it had significant negative relationship with bottom water salinity, and had no significant relationships with sediment environment factors.Nineteen dominant species were found in the 4 cruises besides Ruditapes philippinarum. and the most dominant species were Polychaeta. which could conclude that the macrofauna of Jiaozhou Bay had showed an obvious "miniaturization" trend. ANOSIM analysis showed that the community structure of the 4 cruises were siganificant different. Two groups were indentified through Cluster analysis in winter cruise, spring crusis and summer curise, and four groups were indentified in autumn crusie, respectively. The environment factors which can affect the community structure were different in different waters and even the same waters in different periods, it was evidenced in this study that the water depth had an important effect on the community structure of macrofauna.The results of one-way ANOVA showed that species richness index (d) of winter cruise had significant difference with summer and autumn cruise respectively (P<0.05), and spring curise had significant difference with autumn curise (P<0.05). Evenness index (J’) of spring cruise had significant difference with winter and summer cruise respectively (P<0.05). There were no significant seasonal differences among Shannon-wiener diversity index (H’). The overall means of species richness index, evenness index and Shannon-wiener diversity index were 5.14,0.75 and 3.96, respectively. The results of this research showed that the trends of spatial distribution patterns of the three index were similar, the higher value areas were located at the areas around Station J10, and had a reduced tendency to the surrounding. Richness index had a significant negative relationship with bottom water salinity while evenness index and Shannon-wiener diversity index had significant positive relationship with pH.The average secondary production was 23.16 g (AFDM)/(m2·a). and the average P/B was 1.05. The average secondary production without Ruditapes philippinarum was 82.09 g (AFDM)/(m2·a). and the average P/B was 0.46. The existence of Ruditapes philippinarum could reduce the P/B of macrobenthos.There were 83 species belonged to carnivorous (C) functional group,85 species belonging to detrilivorous (D) functional group.63 species belonging to planktophagous (Pl) functional group,16 species belonging to omnivorous (O) functional group and 4 species belonging to phytophagous (Ph) functional group among the 251 species. The percentage of abundance of the 5 functional groups was D>C>O>Pl>Ph, and the percentage of biomass was D>Pl>Ph>C>O. Integrating the analysis of this research with the historical data, we can find that, the main functional groups of macrobenthos in the subtidal zone were D, C and Pl, and the functional groups was different between intertidal zone and subtidal zone. Because of the lack of hard phase sediment such as rocky mud and rocky shore in Jiaozhou Bay, the algae and other plants were very few, which led to the kind of macrobenthos belonging to Ph functional group was rare.