长江口崇明东滩盐沼湿地围堤工程对底栖动物群落的影响

长江口崇明东滩盐沼湿地围堤工程是以清除入侵植物互花米草为目的而进行的生态修复工程。由于大型底栖动物可作为重要的环境指示生物,分析比较了围堤前后围堤工程内和工程外大型底栖动物群落结构及多样性的变化。结果表明,在2013年围堤工程前和2016年围堤工程后两次调查共采集到大型底栖动物29种,分别隶属于无针纲、多毛纲、腹足纲、双壳纲、甲壳纲和昆虫纲。在2013和2016年围堤外光滩生境分别采集到底栖动物21种和27种,并且所有样线都表现出物种数量增加或持平;然而在围堤内区域,两条全封闭样线(样线2和样线3)由围堤前的12种减少到围堤后的6种,而在保留进出水口的半封闭样线1围堤内由围堤前7种增加到围堤后12种。底栖动物平均密度在半封闭样线1围堤内由围堤前的(75±0)个/m²增加到围堤后的(288±111)个/m²(P=0.091),在全封闭的样线2(2013:(120±17)个/m²; 2016:(7±7)个/m²)和样线3(2013:(359±20)个/m²; 2016:(93±93...

Effects of saltmarsh dike project on benthic community in Chongming Dongtan of the Yangtze Estuary

Chongming Dongtan saltmarsh serves as an important habitat for both migratory and resident birds. However, the exotic plant of Spartina alterniflora has changed the community structure and function of the saltmarsh. Diking at the Chongming Dongtan saltmarsh is an ecological restoration project aiming to eradicate Spartina alterniflora. In order to discuss the influence of human interference on the structure and function of estuarine saltmarsh ecosystem, this study analyzed the change of macroinvertebrates in diversity and composition of species before and after diking project construction, since macrobenthos are considered as important environmental indicators. The quantitative sampling of macrobenthos were carried out in June 2013 and June 2016 to assess the ecological influence of the diking project on the macrobenthos of an Yangzte Estuary. The surveys were conducted each year in three sample lines from inside and outside the dyke. In total, 25 and 27 species were recorded from all sample lines in 2013 and 2016, respectively. All species belonginged to Anopla, Polychaeta, Gastropoda, Bivalves, Crustacea and Insecta respectively. In the mudflat area of outside dyke, 21 and 27 species occurred from 2013 and 2016 respectiely. All lines showed the increased number of species. However, in the inside the dyke area, the number of species changed from 12 to 6 in sample line 2 and 3 (completely closed), and from 7 to 12 in sample line 1 (semi closed) after diking project construction. In addition, the average density of macrobenthos in the inside dyke area were (75±0) ind./m² in 2013 and (288±111) ind./m² (P=0.091) in 2016 from sample line 1, whereas those were decreased significantly (P<0.05) from 2013 to 2016 in sample line 2 (2013:(120±17); 2016:(7±7) ind./m²) and 3 (2013:(359±20); 2016:(93±93) ind./m²). In the outside dyke area, all sample lines showed the increased average density after dyking project construction (from (410±83) to (1184±393) ind./m², P=0.072). The results revealed that preserving the tidal water inlets and outlets had positive effect on macrobenthos inside the dyking project, while the density and diversity both showed an ascending growth outside the dyke area. Moreover, the diking project mostly affected mollusks and polyaetes, which acted as indispensable food sources for birds and fishes. In terms of the change of macrobenthos community, we suggest to preserve water inlets and outlets while diking. Additionally, the gates should be unclosed regularly in order to maintain the connectedness inside and outside the dyke. The study provides an valid evidence for the saltmarsh management and protection of birds and fishes.