东洞庭湖保护区大型底栖动物空间分布格局及水质评价

Spacial distributional pattern of macrozoobenthos and pollution evaluation in East Lake Dongting Reserve

2001年9月对东洞庭湖保护区大型底栖动物进行调查,共记录动物4门8纲20科51种．其中,寡毛类2科18种(35．3％),软体动物8科15种(29．4％),水生昆虫7科14种(27．5％),其他动物4种(9．1％)．软体动物是东洞庭湖底栖动物的最主要类群(占总丰度的71．1％)．其中,腹足类的长角涵螺(Alocinma longicornis)、铜锈环棱螺(Bellamya aerugi- 120sa)、中华沼螺(Parafossarulus sinensis)、纹沼螺(P．striatulus)和寡毛类的苏氏尾鳃蚓(Branchiura sowerbyi)为该保护区的优势种．样点间平均物种丰富度6．3,三种多样性指数(Margalef,Simpson和Shannon)平均值分布为1．38、4．05和1．47．刮食者和直接收集者为底栖动物最重要的摄食类群(占总密度的66．7％和19．9％)．结合GPS,将野外调查数据构建GIS数据库．基于GIS软件平台,运用Kringing插值法,构建动物丰度、生物多样性及污染生物指数(BI)等的空间分布格局,较为直观地反映了保护区底栖动物的分布情况及污染状况．提取出主要生物类群(软体动物、寡毛类和摇蚊幼虫)和5种优势种分布的高浓度块,显示寡毛类与其它两类的分布基本不重叠,主要分布在保护区的东南和西北的深水区域．进一步分析检验各主要分布区域的16种水体理化指标,发现水深是影响保护区底栖动物分布的关键因子,而硫酸盐则主要制约寡毛类的分布格局,硬度是影响软体动物分布的主要因子．全湖平均Hilsenhoff生物指数(BI)值8．18,指示保护区承受较高的有机污染,模拟生成的BI分布图显示,西南部的深水区域、北部及东南部的局部区域水质相对较好,而东北部的沿岸带大部分水体及南部近六门闸的部分区域水体水质相对较差．

Investigation of macrozoobenthos was carried out in East Lake Dongting Reserves in September, 2001. All total, 51 taxa were identified from thirty-two sampling sites, of which, 18 oligchaetes, 15 mollusks, 14 insects and 4 other forms. Mollusks constituted the most dominant group and accounted for more than 70% of the total abundance. Among which, four gastropods, Alocinma longicornis, Bellamya aeruginosa, Parafossarulus sinensis, P. striatulus and one oligochaete Branchiura sowerbyi were the dominant species. The richness and three biodiversity index values （ （ Margalef, Simpson and Shannon） per site were 6.3, 1.38, 4.05 and 1.47, respectively. Assemblages were composed mainly of scrapers （66.7%） and collector-gatherers （19.9%）, and to a lesser extent to other functional feeding groups. The investigation data were compiled and a GIS database of macrozoobenthos was established. A vector boundary map of the lake was digitized and georeferenced, then used to introduce sampling sites. Under the support of GIS software Arcview 3.2 and the relative extension modules （ Spatial Analyst Extension 2.0 and Kringing Interpolator Extension 3.22 SA）, the GIS database was employed to simulate spacial distribution patterns of parameters of macrozoobenthos and Hilsenhoff biotic index （BI）. The simulation process was based on the principle of Kringing interpolation technique. The simulated results were stored as Arcview Grid format with a grid precision of 20 m. The higher distributional pattern of main groups and five dominated species were overlapped based on the 2 - 4 times as mean abundance, and the 16 physical-chemical parameters were collected in these higher distributional regions. The simulated patterns of macrozoobenthos showed that these patterns were relatively high spatial heterogeneity, and distributions of most parameters of macrozoobenthos had usually 2 -4 high value distributed zones in the whole lake, The oligochaete pattern showed basically no overlapping with two other groups, and mainly distributed in deeper region, ANOVA detected water depth was the key factor influencing the distribution patterns of maerozoo- benthos, and SO^2- 4 mainly controlling the pattern of oligochaete, and hardness the main factor affecting mollusks. The average of BI （8.18） revealed the Reserves endured higher organic pollution.