围垦对南汇东滩湿地大型底栖动物的影响

为评价围垦促淤工程对南汇东滩湿地大型底栖动物生态学的影响,根据2004年10月和2009年10月对南汇东滩湿地底栖动物的定量定性调查数据,进行对比分析。结果表明:2004年共采集到大型底栖动物32种,其中在经围垦促淤后形成的堤内、堤外两个区域分别采集到底栖动物20种和21种,2009年堤内外分别为9种和19种,共26种;2004年堤内和堤外优势种分别为8种和4种,共有优势种为中华蜾蠃蜚和谭氏泥蟹,2009年堤内优势种仅有摇蚊幼虫1种,堤外有4种,优势种种类组成也发生了很大变化;2004年大型底栖动物的平均丰度和生物量分别为44.15个/m2和38.80 g/m2,2009年为86.76个/m2和1.97g/m2,2009年堤内、堤外的生物量与2004年相比明显降低,丰度变化则相对较小;运用SPSS软件的单因素方差分析、群落聚类和MDS排序对南汇东滩湿地各断面进行群落结构分析,结果表明围垦是大型底栖动物群落结构改变的一个重要因素,围垦造成堤内底栖动物群落结构发生了明显差异,堤外群落结构变化相对较小。大型底栖动物的生物多样性指数(Shannon-Weiner指数H'、Pielou均匀度指数J'、Margalef物种丰富度指数d和Simpson指数D)受到围垦促淤工程的影响均降低,尤其以围垦圈淤的堤内湿地生物多样性指数最低。围垦促淤工程对盐度、潮汐动力、底质特征的改变以及人类活动等因素是影响大型底栖动物群落结构的主要原因,工程结束后的湿地生态修复十分必要。

The influence of a reclamation project on the macrobenthos of an East Nanhui tidal flat

Quantitative and qualitative sampling of zoobenthos was carried out in October 2004 and October 2009 to assess the ecological influence of a reclamation project on the macrobenthos of an East Nanhui tidal flat.The surveys were conducted each year in four sections: S1—S2 and S3—S4 were inside and outside the dyke,respectively,in 2004,while T1-T3 and T4 were inside and outside the dyke,respectively,in 2009.In total,32 species were found across all areas in 2004,Twenty of these species occurred inside the dyke and 21 species occurred outside the dyke.Twenty-six species were found in 2009 whit nine species inside the dyke and 19 species outside the dyke.On both sampling occasions,most of the macrobenthos were euryhaline species and the rest were freshwater species.From 2004 to 2009 species abundance of Crustacea,Mollusca and Polychaeta exhibited a clear decline inside the dyke,while aquatic insect abundance increased to there species inside the dyke.Outside the dyke,Crustacea and Polychaeta decreased between 2004 and 2009 but Mollusca increased by five species.In 2004,there ere eight dominant species inside the dyke,namely: Corophium sinensis,Uca arcuata,Sesarma dehaani,Ilyoplax deschampsi,Assiminea latercea,Cerithidea sinensis,Capitella capitata and Rhуacodrilus sinicus.Four species were dominant outside the dyke: Corophium sinensis,Ilyoplax deschampsi,Momoculodes limnophilus and Bullacta exarata.Corophium sinensis and Ilyoplax deschampsi were common dominant species.In 2009,Chironomid larvae were the dominant species inside the dyke and Assiminea latercea,Elachisina sp.,Glauconome chinensis and Heteromastus filiformis were the four dominant species outside the dyke.The average abundances and biomass values for macrobenthos were 44.15 ind/m2 and 38.80 g/m2 in 2004 and 86.76 ind/m2 and 1.97 g/m2 in 2009.Macrozoobenthos biomass decreased significantly between 2004 and 2009,although abundance did not decline.Data were analyzed using SPSS,one-way ANOVA,hierarchical cluster analysis and non-metric multidimensional scaling(MDS).The results of cluster analyses and MDS indicated that the eight sections were divided into four groups with different macrobenthic communities: the first group included four sections,S1-S4 from 2004;the second group included T1 and T2 from 2009,which were statistically very different from S1 and S2;while the last two groups were T3 and T4.The structure of the macrobenthic community in T4 was very similar to that in S3.T3,on the other hand,was subjected to frequent human disturbance generating a greater level of habital heterogeneity. Reclamation is an important factor of changing macrobenthic communities.In this study,the composition of dominant species changed markedly with a clear decline in species diversity(Shannon-Weiner index,Pielou′s evenness index,species richness and Simpson′s diversity index).The lowest diversity index was recorded in the reclaimed area.Reclamation on tidal flats changes salinity,tidal action and tidal flat sediment characteristics and dynamics.Human activities have a major impact on zoobenthos communities.Ecological restoration following reclamation projects is essential and may include building water gates,or restocking with macrobenthos and native plant species that can adjust and survive in the new environment.