河口盐沼植物对大型底栖动物群落的影响

Influence of Characteristics of Scirpus mariqueter Community on the Benthic Macro-invertebrate in a Salt Marsh of the Changjiang Estuary

通过对长江口崇明东滩盐沼海三棱藨草带大型底栖无脊椎动物进行取样调查 ,研究了不同盐沼带的底栖动物群落结构及其多样性特征 ,分析了盐沼植物群落特征与底栖动物群落的关系。研究发现 :1沿着河口盐沼海拔梯度 ,从低位盐沼到高位盐沼 ,底栖动物群落结构及多样性具有明显的梯度变化 ;2盐沼植被与底栖动物群落有密切的关系 ,尤其是植株高度、地下部分生物量与底栖动物密度、Shannon-Weiner多样性指数、物种丰度的相关性最显著 ;3盐沼植被影响底栖动物群落 ,是由于植物的地上部分和地下部分结构导致盐沼生境结构复杂 ,增加了沉积物表层环境的结构异质性 ,使生境多样化 ,给底栖动物提供了大量生活空间 ;4不同盐沼带海三棱藨草群落的差异 ,提供了盐沼表层地貌的变化。这种变化及植物结构的复杂化 ,在为一些动物提供拓殖地的同时 ,也为底栖动物躲避捕食者提供了良好的避护所 ;5盐沼植被可以改变河口潮滩生境中的沉积环境 ,并通过消浪。

Both intertidal plant community and zoobenthic community are important parts of estuarine ecosystem, which determined many significant ecological processes in the estuarine ecosystem. Survival of zoobenthos in the tidal flat of estuary is influenced by stability and heterogeneity of habitats closely related to tidal dynamics, sediment conditions, characteristics of physiognomy and vegetation pattern. Scirpus salt marsh is widespread throughout the Changjiang estuary, China. It is one of the most common plant species in the tidal wetland as primary colonizer. Vegetation, sediment properties, and macrofaunal communities of Scirpus mariqueter habitat in the salt marsh of the estuary were described in this paper. Our objectives were to describe and compare macrofaunal assemblages of a variety of S. mariqueter habitats, examine the effects of salt marsh vegetation on the macro invertebrate community of the associated sediment, and evaluate relationships between habitat properties of salt marsh and macrobenthic community. This study sites is located at the eastern beach of Chongming Island, in the Changjiang estuary, China. S.mariqueter forms dense pure stands in the study site, stretching about 2 5 km from bare beach to Phragmite asutrilia community that distributes near the reclamation dike, about 50 cm above the mean water level. 6 stations were set, namely A and B, C and D, E and F, roughly belonging to low marsh, middle marsh and high marsh respectively, at an interval of about 500m along elevational habitat gradient. Faunal samples consisted of 4 randomly located quadrat (50×50 cm 2, 20 cm deep) at each station. Samples were sieved through 1.0 mm meshes. The retained plant material separated into structural components (roots, rhizomes, corms and stembase below ground) was dried to constant mass for 48 h at 80℃, then weighted. Macrofauna founded were identified and enumerated. Numerical data analyses included Shannon Weiner index ( H ′), Pielou index ( J ) and Margalef index ( S ). Similarity matrix was constructed using the Bray Curtis similarity measure on transformed (√√) data. Subsequent ordination from the similarity matrix was produced by multidimentional scaling (MDS). Significance testing for differences in faunal composition between sampling sites and linear regression among all plant and faunal community parameters were down. Based on the data collected from samplings on S. mariqueter community and the benthic macro invertebrate community in the salt marsh in the eastern beach of Chongming Island in the Changjiang estuary, the structure of benthic macro invertebrate community, diversity, and relation between plant community and zoobenthic community were analyzed. Major conclusions from this research are as follow. Along the elevational gradient, plant community and zoobenthic community zonation was conspicuous in the mud flat of the Changjiang estuary. From low salt marsh to high salt marsh, each zone has its dominant species. Mollusc predominates in the low salt marsh, in which Corbicula fluminea and Gammerus sp. were dominant species. In the middle salt marsh the dominant groups were small snail and crab, in which Stenothyra glabra, Rissoina sp. and Ilyrplax deschampsi predominated in there. Helice tridens tientsinensis, Sesarma denaani and Rissoina sp. were dominant species in high salt marsh. There were significant gradient variation in community structure and diversity of zoobenthos from low marsh to high marsh. Zoobenthic community zonation but only related to habitat differentiation induced by variation of plant community along elevational gradient and topographic heterogeneity, but also was result of zoobenthos adapting to environment. There was close relationship between vegetation of salt marsh and benthic community. The main factors explaining the differentiation in density, Shannon Weiner indices and species richness of zoobenthos along the habitat gradient were shoot density, total plant biomass, plant biomass below\|gr