| Benthic macroinvertebrate is an important biotic component of lake ecosystem and plays multiple functions in aquatic ecosystem. This thesis is based on the quarterly investigation of the benthic macroinvertebrate community at 28 sampling sites in Ulungur Lake during November,2006 to July,2008. The pattern of spatial and temporal variation of the species composition, the dominant species, density and biomass of benthic macroinvertebrate were analysized. The water quality of this lake was evaluated on the basis of benthic macroinvertebrate community and the potential fish production provided by benthic macroinvertebrate was estimated. The main results are as follows:1. A total of 87species were observed in Ulungur Lake,14 species of Oligochaeta 16.2%,61 species of Insecta 70.1%,7 species of Mollusca 8.0% and 5 species of others 5.7%.2. The species composition of benthic macroinvertebrate manifested significantly temporal and spatial characteristics. The benthic macroinvertebrate species number was highest in winter, followed by the autumn, spring and summer both in 2006-2007 and 2007-2008. The species composition of benthic macroinvertebrate was dominanted by Insecta, followed by Oligochaeta, Mollusca and others. The horizontal variations of benthic macroinvertebrate species in 2006-2007 was in accordance with that in 2007-2008, and the species number of benthic macroinvertebrate was highest at sampling site 21# (27and 26 species, respectively) and lowest at sampling site 26# (3 and 2 species, respectively).3. The mean density and biomass of benthic macroinvertebrate in Ulungur Lake were 1015.01 ind./m2 and 9.83 g/m2. The density and biomass of Insecta were 503.27 ind./m2 and 8.67 g/m2, accounting for 49.58% of total density and 88.20% of total biomass, respectively, The density and biomass of Oligochaeta were 482.89 ind./m2 and 0.42 g/m2 g/m2, accounting for 47.57% and 4.27%, respectively. The density and biomass of Mollusca were 17.98 ind./m2 and 0.38 g/m2, accounting for 1.78% and 3.78%, respectively. The density and biomass of others were 10.88 ind./m2 and 0.36 g/m2, accounting for 1.07% and 3.66%, respectively.4. There were remarkably spatial and temporal variations in density and biomass of benthic macroinvertebrate. The seasonal distribution of density and biomass of benthic macroinvertebrate both in 2006-2007 and 2007-2008 had the same pattern: winter>autumn>spring>summer. The one-way ANOVA analysis showed that:the density of benthic macroinvertebrate in winter and summer were significantly different (P<0.05) and the biomass of benthic macroinvertebrate among the summer, spring and winter were significantly different (P<0.05). The density and biomass of benthic macroinvertebrate in Ulungur Lake showed remarkable changes in the horizontal distribution during 2006-2007 and 2007-2008. The sampling site 27# in Jili Lake and the sampling site 26# in Houpaozi had the maximum and the minimum annual average density of 2450 ind./m2 and 68 ind./m2, respectively. The sampling site 14# and the sampling site 26# had the maximum and the minimum annual average biomass of 27.13 g/m2 and 0.87 g/m2, respectively.5. Among the major environmental parameters, the water depth had highly significant influence on the spatio-temporal distribution of biomass (P<0.01, n=28) and significant influence on the spatio-temporal distribution of density (P<0.05, n=28).6. During 2006-2008, Ulungur Lake was classified as mesotrophic water when the indicator species were adopted to assess the eutrophication level, but was categorized into eutrophic water when biomass index was used. While the physiochemical index indicated that the lake belonged to mesotrophic state. Based on the results of evaluation of Shannon-Wiener diversity index (H'), Goodnight biotic index (GBI), Margalef richness index (D), Chandler's score system (CS) and Integrated pollution index (BI). Ulungur Lake belonged to slight-middle pollution, similar to the evaluation result (middle pollution) shown by the physiochemical index.7. According to the annual mean biomass of benthic macroinvertebrate, the potential fish production provided by benthic macroinvertebrate were 5.36×105 kg and 5.12×105 kg in 2006-2007 and 2007-2008, respectively, which were lower than those in 1985-1987 (1.973×106kg).
|
PDF Full Text Request