Community structure and species diversity of benthic macroinvertebrates in Taihu Basin of Jiangsu Province

Abstract

To explore the characteristic of community structure and species diversity of benthic macroinvertebrates, samples were collected three times at 120 sampling sites in Taihu Basin of Jiangsu Province. Twenty-nine sampling sites were located in Lake Taihu, and the number of sites in other lakes, rivers, reservoirs and streams were 20, 40, 15 and 16, respectively. The three investigations were conducted in the periods from January to March, from July to August and from October to November in 2013. In total, 280 taxa of benthic macroinvertebrates from 124 families and 6 phyla were recorded. The taxa number (4-51), density (5.5-23363.4 ind./m2) and biomass (0.1-6269.2 g/m2) varied greatly among sites, and community structure differed significantly among water bodies. In the western hilly region, the community of streams were dominated by aquatic insects from Ephemeroptera, Trichoptera and Odonata, while reservoirs were mainly dominated by Chironomidae larvae. In the eastern plain area, pollution-tolerant oligochaetes dominated the community of rivers, while lakes were dominated by Chironomidae larvae, Oligochaeta and Mollusca. Cluster analysis and One-way analysis of similarity classified the 120 sites into nine groups characterized by different characteristics species, showing the hierarchical gradient of sampling sites in lakes, rivers, reservoirs and streams. Streams(group IX) were the least stressed by integrating the results of abundance-biomass curves, characteristics species and diversity of each affinity group. Species richness and evenness were relatively lower in central region(group II) and macrophytes dominated areas(group III) of Lake Taihu, whose biomass curves were above the abundance curves and dominated by Mollusca, Malacostraca and Oligochaeta, indicating that the communities suffered relatively weak disturbance. The biomass curves of groups including reservoirs (group VII), lakes (group IV) and rivers (group VI), which were in the out-flow direction of Lake Taihu, were very close to or intersected with the abundance curves and dominated by Chironomidae larvae, Oligochaeta and Gastropoda, indicating that the communities were moderately disturbed. However, the other groups (group I, V and VIII) were only dominated by Chironomidae larvae and Oligochaeta, indicating intense disturbance. Community structure and spatial distribution of benthic macroinvertebrates in Taihu Basin of Jiangsu Province were strongly correlated to two ecological factors-habitat complexity and water quality, which could be used by managers and policy makers to evaluate and improve restoration practices.