The Timeperal-spatial Variation Of Zoobenthos And Its Functional Groups In Yellow River Delta Wetlands

The large zoobenthos played an important role on the transformation process of substance and energy in wetland ecosystem. However, the correlation study centralized on the level of species inventory presently. To perfect the structure and composition in Yellow River delta wetlands, and revealed the spatial and temporal variation of large zoobenthos, field surveys carried out on their species composition, diversities, community structures and environmental factors in different habitats on spring and summer in 2006 and summertime in 2008. Moreover, we compartmentalized the functional groups of the zoobenthos. A total of 41 zoobenthos species were found, of which consisted of Mollusk, Annelid and Arthropod, Planktophagous group, phytophagous group, camivorous group, omnivorous group, detritivorous group composed the functional groups of the zoobenthos of Yellow River delta wetlands. The contents and results were summarized as follows:(1) The spatial distribution of zoobenthosIn the horizontal space, from the estuary to inland, 80% of the Mollusk dispersed in low tidal beach. The number of Annelid in descending order is aquatic plant community, mesophyte community, and xerophyte community. The Arthropod gradually converted from crustacea to insectacra. Dominant species varied clearly among different habitats. High community similarities of zoobenthos existed between woodland and farmland and lower community similarities existed between other habitats. Species number, biomass and diversity index in descending order was aquatic plant community, mesophyte community, xerophyte community, and that of evenness index, abundance index was mesophyte community, aquatic plant community, xerophyte community. In vertical distribution, 95% of the species and individuals distributed within top 10cm depth of the surface layer.(2) The temporal distribution of zoobenthosSpecies number of zoobenthos in spring has little difference when compared with that of the summer, Comparing with other investigation, species in Yellow River delta wetlands is short of. Biomass in different habitats and in different season changed a little. Biomass in descending order was bulrush land, cotton field, intertidal zone, shelter forest and grassland. Biomass in summer is higher than biomass in spring.(3) Compartmentalize the functional groups of the zoobenthosThere are 14 kinds phytophagous group, its representative species are Sympiezomias velatus, Agrotis segetum, Holotuichia parallela. phytophagous group is preponderant group. There are 7 kinds planktophagous group, its representative species are Stenothyra glabar, Assiminea lutea. There are 6 kinds detritivorous group, its representative species arePerinereis aibuhutensis, Pirata boesenberget. There are 6 kinds detritivorous group, its representative species are Perinereis aibuhutensis, Pirata boesenberget. There are 6 kinds camivorous group, its representative species are Capitella capitata, Phertima tschiliensis.There are 8 kinds omnivorous group, its representative species are Formica japonica, Artemia sp, Hyale grandicornis.In the space distribution, from estuary to inland, planktophagous group distributed in aquatic plant community. phytophagous group distributed in mesophyte community. In the temporal distribution, there was little diversity in functional groups composition and diversity indexes of zoobenthos between different seasons. Bulrush land had most difference. There was 2 kinds detritivorous group in spring, and disappeared in summer.(4)Analysis of the relationship between zoobenthos and environmental factorsIn all of the soil physical factors, the relativity between moisture in the soil and zobenthos is the most significant one, except species, others are all above the significant level; the influence of soil salinity on zoobenthos abundance is large, the relativity between them was 0.604. Diversity indexes of zoobenthos negatively correlated with the soil PH expect species. Water-solubility organic C much negatively correlated with biomass, correlational index is -0.738. Inorganic C much positive correlated with biomass. Available N much negatively correlated with biomass. Available K much negatively correlated with Abundance index. Available P much correlated with Evenness index (0.810).(5) Comparability of zoobenthos and Cluster analysisThe environmental factor at sampling points are the more similar, the similarity of benthic fauna are also higher. Through the analysis of the comparability index of zoobenthos showed that the similarity of zoobenthos community and the differences of zoobenthos community composition. The cluster analysis of environmental factor of zoobenthos and the similarity analysis of the comparison between zoobenthos communities, the results showed that the more similar living environment, the higher the coefficient of similarity. The similarity index between forest land and farmland was highest, but lower on the other habitat.