Macroinvertebrate Assemblages And Its Application In The Water Management

1 The Advancement of Biotic Index of Water Quality Bioassessment Using Benthic Macroinvertebrate Assemblages and Its Perspective in ChinaThe history of bioassessment of rivers is a good hundred years old, and the importance of bioassessment is recognized gradually. Among the biological communities, the macroinvertebrates are by far the most frequently used group for bioassessment in standard water management. This paper reviews the history and development of three principal bioassessment approaches--saprobic indices, biotic indices and scoring systems, diversity indices, and critically evaluates these three principal approaches. Comparing with the developed countries, the development of biomonitoring in China was far behind. Impediments to biomonitoring in our country include:the insufficient taxonomic literature, the tolerance values of benthic macroinvertebrates have not scientifically established, standard sampling tools and methods for benthic macroinvertebrates and bioassessment criteria of BI have not been established, besides these, people pay less attention to biomionitoring. EU member states, North America and Australia have already had their national river monitoring programmes, respectively. Lacking standard biotic index is the most important problem in China. Presently, the BI is extended to all kinds of water bodies (stream, river, lake and reservoir), which provides a good opportunity for popularizing BI. We suggested that it is urgent to conduct study on BI and its criteria in water quality biomontoring, and to set up a standard biomonitoring programmes based on BI eventually, giving full play to the importance of biological monitoring in water management.2 Community Structures of Macroinvertebrates and Bioassessment of Upstream Qinhuai RiverBenthic macroinvertebrates assemblages were collected from the upstream of the Qinhuai River in April,2009. A total of 63 macroinvertebrate taxa were found including 30 genera and 12 families of Insecta,19 species and 11 genera in 9 families of Mollusca,9 species and 7 genera in 2 families of Oligochaeta. Our study indicated that BI had a better discrimination than Shannon-Wiener diversity index. The Pearson's correlation analysis showed that BI corresponded strongly with TN (r=0.44, p<0.05) and NH4+(r=0.40, p<0.05), that Shannon-Wiener diversity index had no significant correlation with TN (r =-0.187, p=0.370) and NH4+(r=0.44, p=0.451). The results showed that the upper reaches of Qinhuai River suffered from severe pollution and the water quality of Nanjing area was worse than that of Jurong's.3 Selection of indicator species of major environmental variables affecting macroinvertebrate communities in the Xitiao Stream, Zhejiang, ChinaThe land covers for 55 sampling sites were estimated at sub-basin, riparian-zone and local scales using 2003 satellite image and a Digital Elevation Model. By applying the redundancy analysis (RDA) the minimum variables combination-NH4+, canopy, conductivity, sub-scale cropland% and habit complexity which can significantly explain the macroinvertebrate communities were screened. The result of variance partitioning showed that NH4+was the most important variables affecting macroinvertebrate communities in the Xitiao Stream, and sub-scale cropland% was also another important factor. Under the species fit range between 50% and 100%, Cheumatopsyche sp.1 and Cheumatopsyche sp.2 were finally obtained, the abundance of Cheumatopsyche increased as the NH4+ and the sub-scale cropland% increased. The Cheumatopsyche has following advantages:widely distributed, could be easily collected, with moderately tolerance, actively drift, large body size with slower turnover rates and ecological plasticity, they exhibit to be excellent indicators for the NH4+and the sub-basin scale cropland% of disturbed sites in the Xitiao Stream.4 Research on the river nutrients threshold based on benthic macroinvertebrateassemblages:a case study in the upstream of the Xitiao Stream, Zhejiang, China Eutrophication has become a global problem and is one of the major environmental problems faced by China. At present, studies on the water eutrophication were mainly focused on lakes and reservoirs in China, whereas studies of river eutrophication were few. Based on the stress-response between macroinvertebrate assemblages and nutrients, we used nonparametric deviance reduction (change point analysis) to determine breakpoints in nutrient concentrations at which there was the most abrupt biotic response in the upstream watershed of the Xitiao Stream. The results indicated that the threshold was 1.409mg·L-1for TN and 0.033—0.035mg-·L-1for TP. The TN and TP concentrations of reference sites and city sewage polluted sites are lower and higher than the changepoints respectively. Nutrient concentrations higher than the thresholds may lead to the degradation of macroinvertebrates structures. We wish to set up nutrients criteria based on aquatic organisms, and give full play to the importance of biological monitoring in water management, for example, a total maximum daily load (TMDL) estimate.