| Benthic diatom is an important indicating group of biological monitoring, and it has been widely used for assessment of river health. However the species lists of benthic diatoms for biological biomonitoring are still incomplete in many watersheds in China. It is difficult for local governments and managers of river systems to carry out biological monitoring program. Investiagtion to establishing species lists in representive water systems is required. In 2015, such an investigation was run, in which 77 samples were collected in 4 sampling periods from Liuxi River, a typical meddle sized river in Gunagzhou(Guangdong Province). The biological and environmental data were analyzed and the results were summarized as follows:1. Two hundred and fifty species of benthic diatoms in 55 genera were observed from 21 sites and 4 sampling periods. Achnanthidium?Navicula?Nitzschia and Gomphonema were the main dominant genera with high frequency and high relative abundance. Diatom diversity indexes, such as richness and true Shannon-Wiener diversity index, showed a certain spatial pattern increasing with river class. Community dissimilarity of benthic diatoms decreased from class 1 to class 2 but increased in class 3. Structure of benthic diatoms had temporal and spatial patterns by Two-Way PERMANOVA analysis.2. Environmental variables had certain temporal and spatial patterns. Redundancy analysis showed that environmental variables could significantly explain the variation of benthic diatom communities,especially altitude, turbidity, dissolved oxygen and other nutrients had high explanation ability. Variation partitioning showed that nutrition is the most important factor affecting community structure of benthic diatoms.3. The sample size increases up to 600 shells to cover most of the diatom species(15.2%).4. Biological Diatom Index could reflect the environmental information of sampling sites, and was suitable for the health assessment of the water quality the rivers like the Liuxi River. |
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