长江镇江段不同生境类型底栖动物群落结构研究

MACROZOOBENTHIC COMMUNITY STRUCTURE IN DIFFERENT TYPES OF HABITAT,ZHENJIANG REACH,THE YANGTZE RIVER,CHINA

2010年3～12月在长江镇江段进行4次采样共采集到底栖动物26种,隶属于7科21属,其中水栖寡毛类2科7属12种,多毛类1科1属种,软体动物2科4属4种,水生昆虫2科9属9种。长江镇江段共有4个优势种:厚唇嫩丝蚓(Teneridrilus mastix)、苏氏尾鳃蚓(Branchiura sowerbyi)、多鳃齿吻沙蚕(Nephthys polybranchia)和长足摇蚊(Tanypus sp.)。底栖动物平均栖息密度和生物量分别为74ind./m2和0.2g/m2。各种生境类型中,保护区的底栖动物密度和生物量相对较高,北湖次之,主航道最低。同时存在着季节变动,密度以春夏较高,秋冬较低,生物量以春秋较高,冬夏较低。各季度功能摄食类群密度相对丰度以直接收集者所占比例较高,滤食收集者次之。比较长江下游各江段,底栖动物群落有较大差异:密度最高值出现在扬中段,最低值出现在镇江段;生物量最高值出现在江阴段,最低值出现在镇江段;而种类数在镇江段和扬中段较高,江阴段较低。

With the rapid economic development and overexploitation of resource,the aquatic ecosystem of the Zhenjiang Reach of the Yangtze River is threatened by all kinds of disturbances.In order to fully understand the present status of the macrozoobenthic community,this study was carried out from March to December in 2010.Sediment samples were collected with a 1/16 m2 Peterson grab and cleaned with a 420 μm sieve.Animals were sorted in a white porcelain dish and specimens were preserved in 10% formalin.Altogether 26 species belonging to 7 families and 21 genera were recorded,including 12 species of oligochaetes,1 species of polychaetes,4 species of molluscs and 9 species of aquatic insects.The dominant species were Teneridrilus mastix,Branchiura sowerbyi,Nephthys polybranchia and Tanypus sp..The standing crop of the macrozoobenthos was 74 ind./m2 in density and 0.2 g/m2 in biomass.Among three habitats,higher biodiversity were found in conservation district.Generally,higher density of the macrozoobenthos was observed in spring and summer,while the biomass was found greater in spring and autumn.The composition of the functional feeding groups was mainly determined as collectors.Comparisons of macrozoobenthic community characteristics among the lower reaches of the Yangtze River were carried out.Density was highest in Yangzhong Reach and lowest in Zhenjiang Reach.However,biomass was highest in Jiangyin Reach and lowest in Zhenjiang Reach.Zhenjiang Reach and Yangzhong Reach had more species than Jiangyin Reach.