围垦对崇明东滩潮沟大中型浮游动物群落结构的影响

为揭示围垦对潮间带潮沟水域浮游动物群落结构的影响,于2008年4月至2009年12月在崇明东滩选取3条围垦潮沟共9个站点进行两年4个季节的浮游动物采样调查,分析了浮游动物的种类组成、优势种、现存量及物种多样性等生态特征参数在围垦前后的变化.结果显示,围垦后潮沟浮游动物种类数明显减少,主要是桡足类物种的减少;围垦前以桡足类为主要优势种,围垦后则以日本新糠虾(Neomysis japonica)为主要优势种;围垦后较围垦前丰度明显降低,生物量则相反;且季节变化趋势也发生了较大变化.围垦工程阻断了潮沟与潮沟外长江口水域物质、能量的交流,导致围垦潮沟内水体的盐度等环境因子发生较大变化,从而对该水域浮游动物群落结构产生重要影响.因此,建议围垦时在坝下修建通水管道等以沟通内外水系,另在被围区域可利用原有潮沟投放水产养殖动物,这对维持湿地生态系统的功能,特别是为崇明东滩水鸟提供不同的栖息地具有现实意义.

The Effect of Reclamation on Community Structure of Macro-meso Zooplankton in Tidal Creeks of the Chongming Dongtan

To reveal the effect of reclamation on community structure of zooplankton in tidal creeks,zooplankton were sampled at 9 stations in three reclamation tidal creeks during four seasons from April 2008 to December 2009,and the variations of species composition,dominant species,standing crop,and species diversity of zooplankton before and after reclamation were recorded.The results showed that the species number of zooplankton reduced significantly due to the decrease of copepods,and the main dominant species was Neomysis japonica instead of copepods after the reclamation.Moreover,the abundance of zooplankton decreased obviously,while the biomass increased evidently after reclamation,and the seasonal variation varied significantly before and after reclamation.Exchanges of material and energy between tidal creeks and Yangtze River estuary water were blocked by reclamation project,resulting in great changes of salinity and other environmental factors of reclaimed tidal creek waters,and these changes had an important impact on the biology community in the waters.This finding indicate the importance to build pipelines under the reclamation dam to connect tidal creeks and outside water.Meanwhile,it is significant to maintain wetland ecosystem functions to stock aquatic animals in the original tidal creeks,which also provides different habitats for waterfowl of Chongming Dongtan.