平原河网地区大型底栖动物群落结构及其与环境因子的关系

大型底栖无脊椎动物是河流生态系统的重要组成生物,具有活动范围相对固定、生命周期较长、生活习性相对稳定等特点,可有效指示河流水质和水生态系统健康状况。有关大型底栖生物群落结构特征及其与水环境之间的关系研究一直是河流生态系统的研究热点。底栖动物具有较强的地域性,其群落结构特征受当地的自然环境特征和社会经济发展程度的双重因素影响。为研究典型平原河网地区的底栖动物群落结构及对水环境状况的响应特征,在上海市选取了83个河道断面进行大型底栖动物采样分析,共获取底栖动物20个分类单位（种）,其中软体动物10种,环节动物6种,节肢动物4种。上海河道底栖动物群落结构总体呈现结构单一、物种丰富度低、高度耐污性等显著特征,环节动物的栖息密度和出现频率均最高。城市化水平的空间差异性直接影响底栖动物空间分布的异质性,由市区至近郊、远郊,物种数从11种逐渐上升至15种,而栖息密度则由8 776.3个/m2下降至690.3个/m2。底栖动物群落结构的空间分布特征与水质理化指标的空间分布特征具有良好的对应性,水质空间变化导致环节动物和软体动物、节肢动物的空间分布存在一定交错性,耐污性较强的环节动物主要分布在有机污染重、溶解氧低的市区河道断面,而喜清洁环境的软体动物和节肢动物主要分布在水质较好的郊区断面。寡毛纲物种的栖息密度与溶解氧质量浓度呈显著负相关性。

Characteristics of macrobenthos community structure and its relationship to environmental factors within a typical plain river network

Benthic macroinvertebrates are abundant in the streams and lakes. Since most of them have sessile mode of lives or limited migration distance, their species and numbers are important parameters to access the habitat environmental quality. Collection of macroinvertebrates biosurvey data has worldwidely been used as a routine approach by most water quality agencies. The communities of benthic macroinvertebrate have distinct geographical characteristics, correspondingly reflecting the quality of natural environment and socio-economic development of surronding regions. To understand and characterize the benthic biota and elucidate their adaptive responses to environmental factors, we investigated benthic macroinvertebrate fauna at 83 sites in Shanghai city, which is a representative plain river network. In total, we found 20 taxa of the benthic macroinvertebrate： 10 Mollusca, 6 Arthropoda and 4 Annelida. Our data showed that macrobenthos community structure processed typical characteristics including simple composition, low species richness and high pollution-tolerant. Among all species, Arthropoda was found to be the most frequently detected one with highest population density. The spatial heterogeneity of macrobenthos community was linked to the regional extents of urbanization level, respectively. From the downtown area to suburb or rural areas, the number of species increased from 11 to 15 while habitat density decreased from 8776.3/m2 to 690.3/m2. Moreover, it exhibited high degree of correlation between the physicochemical indicators of water quality and the spatial distribution of macrobenthos fauna. Most species of Arthropoda are high pollution-tolerants and were absolutely dominant in the downtown area with heavier organic pollution and lower dissolved oxygen. In contrast, the species of Mollusca and Annelida predominated in the suburb and rural areas with lighter pollution and higher dissolved oxygen level. The significant negative correlation was found between population density of Oligochaetes and dissolved oxygen concentration. Taken together, Mollusks are indicator species showed relatively healthy aquatic environment and annelids such as oligochaetes are indicator species indentifying organic polluted and low-DO environments.