| Aritifical lakes formed from land subsidence play a central role in ecological restoration of Huainan coal mine area, the ecosystem structure and functional health is the precondition to guarantee the sustainable utilization of mining area water resources. Research the subsidence lake's biological community structure energy flow?material cycle and reveal its development and change rule can provide theoretical gist to help us with deeply understanding the structure and function of aquatic ecosystem.There four small subsidence lakes at PXPJ site, PXGQ site, PXXQ site in Panxie mining area and HXH site were chosen as research sites, lake quarterly investigation was conducted in 2014-2015 to analyzing the characteristics of the aquatic environment and the community of plankton. The Ecopath model was used to analyze the trophic structure in the PXXQ ecosystem. The main research results and the relevant conclusion were shown as the following:1) Averaged annual concentrations of total nitrogen (TN) in the four site are 1.69 mg/L,0.91 mg/L,2.82 mg/L and 4.26 mg/L, averaged annual concentrations of total phosphorus (TP) in the four site are 0.104 mg/L,0299 mg/L,0.045 mg/L and 0.381 mg/L, total Chlorophyll a concentration were 28.3 mg/m3,26.9 mg/m3,38.1 mg/m3 and 53.6 mg/m3 respectively. Four lakes belong to eutrophic lake, and HXH is the most eutrophic site.2) A total of 136 species of phytoplankton were identified, which belong to 7 phyla,9 classes, 18 orders,34 families and 74 genera. The primary phytoplankton species were Cyanophyta, Chlorophyta, and Bacillariophyta Chlorophyta, Cyanophyta, and Bacillariophyta had 59,24 and 22 species, respectively accounting for 45.0%,18.3% and 16.8% of the total specie, respectively. The predominant species at PXPJ site are Chlorophyta, Bacillariophyta and Cryptophyta The predominant species at PXGQ in summer and autumn is Cyanophyta accounting for 61.5% and 46.2%, respectively. The predominant species at PXXQ site in spring is Cryptophyta, in summer and autumn is Cyanophyta The predominant species at HXH site in summer and autumn is Cryptophyta accounting for 70.52% and 66.8%, respectively.3) A total of 34 species have been recorded, which belong to fifteen genera,25 species of thirteen genera at PXPJ site.24 species of thirteen genera at PXGQ site,20 species of eleven genera at PXXQ site and 11 species of 5 genera at HXH have been indentified. Keratella valga, Trichocerca rousseleti, Asplanchna priodonta, Pofyarthra trigla Ehrenberg Asphnchna brightwelli. Gosse were the dominant species in the lakes.4) A total of 26 species have been recorded, which belong to twenty-three genera,16 species of thirteen genera at PXPJ site.13 species of twelve genera at PXGQ site,19 species of fourteen genera at PXXQ site and 20 species of 11 genera at HXH site have been indentified. Bosmina longirostris, Mesocyclops leuckar, Thermocyclops were the dominant species in the lakes.5) Ecopath model of PXXQ ecosystem involved 14 functional groups, including fish(Channa argus, Pelteobagr fulcidraco, Cyprinus carpio, Carassius auratus, etc), detritus, plankton, which basicly covered the main trophic structure composition and the main energy flow process of Xieqiao ecosystem. In the end, the ecosystem was integratied into five trophic levels. The conversion efficiency from trophic level to trophic level were 12.3%,13.5% and 14.7% respectively, with an averaged value of 13.5%, the ratio among trophic level and system total input of each group decreased gradually along the food chain. The trophic flow of Xieqiao ecosystem has two ways, one is using phytoplankton as the beginning of prey on the food chain and the conversion efficiency was 13.3%; Second is using detrital as the beginning of detrital food chain and the total conversion efficiency was 13.4%.The mixed trophic impact shows there are negative effects of serf group, catch fleet have a significant negative effect on fish group, but to shrimp?benthos?zooplankton and phytoplankton, especially the shrimp group,there are positive effects. As primary productors in ecosystem, detritus?phytoplankton has the positive effects on other group. Hypophthalmichthys molitrix as the most important commercial fishes have the significant positive effect on other groups in ecosystem. Cyprinus carpio, Aristichthys nobills, Hypopthalmichthys molitrix and shrimp have a high predator overlap index, while rotifer and crustacean have a high prey overlap index.There are a series of parameters to evaluate the ecosystem's stability and maturity. PXXQ ecosystem's total primary production/total respiration is 2.207, higher than 1,which indicated that system had not reached a stable stage. System omnivory index (SOI) and connectance index (CI) were important parameter reflecting the ecosystem internal connection the CI value and SOI value of this research system are 0.284 and 0.099 respectively, and the functional groups of the site is weak, and the stability of the system is not enough. Finn's cycling index and Finn's mean length can show the maturity of the system,7.93% and 2.849 respectively, low material recycling ratio indicate the short path that nutrient flow through the food chain and low system maturity. |
PDF Full Text Request