淦河流域底栖藻类特征及其生态学研究-@@专业论文.docxVIP

中南民 中南民族大学硕士学位论文 淦河流 淦河流域底栖藻类特征及其生态学研究 PAGE PAGE V VI VI ABSTRACT Benthic algal assemblages on natural substrata, water quality, and habitat conditions were investigated in 21 locations of the Ganhe River watershed from February to December 2011, several researches were carried out during investigation period: 1) the spatial-temporal patterns of concentration of chlorophyll a (Chl a), ash free dry mass (AFDM), and autotrophic index (AI) of benthic algae. 2) the spatial-temporal patterns of benthic diatoms and their relationships with environmental variables. 3) application of biological diversity and three diatom indices including Trophic Diatom Index (TDI), Specific Polluosensitivity Index (IPS) and Biological Diatom Index (IBD) to estimate the health status of the Ganhe River watershed. The main results are as follows: The water quality of agricultural region in upstreams belonged to class II to class IV based on TN and TP levels during the survey, and class IV to bad classⅤin the urban region. There were muti-peak fluctuation characteristics in concentration of Chl a and AFDM, and significant correlation between them （r=0.655，P＜0.001）. Regression analysis showed that total phosphorus (TP) only explained 5.07% (P=0.013) of the variability in benthic algae Chl a. AI varied between 54.9 to 806.5 with overall average of 144.7 throughout the year, had no significant differences between the upstream and downstream samples, and it was not related to the level of TP in water column (r=-0.074, P=0.456). A total of 503 taxa (including variations) in 22 families of 50 genera were observed, in which 487 taxa, 12 taxa, 4 taxa and 1 taxon belonged to Bacillariophyta, Chlorophyta, Cyanophyta and Chrysophyta respectively. Diatoms comprised 96.6% of the total taxa. Benthic diatom communities in the upstream samples (S1-S15) were relatively stable in the seasonal changes throughout the year, and Achnathes minutissima, Cocconeis placentula and Cymbella affinis were the predomina