The Periphytic Algae Community Structure And Stream Ecosystem Health Assessment In Liao River Basin, China

River ecosystem is one of the major natural ecosystem, natural resources and main channel of biosphere material circulation and energy flow. River ecosystem health evaluation is important to maintain river ecosystem integrity, to establish scientific and rational river management programme. Liao river Basin is one of China seven major river basin, it is the research hotspot of watershed ecology. In a three-year time(respectively, in September 2012 and September 2013 and September 2014), 5 stream segment of Liao river Basin(Dongliao river, Xiliao river, Liao river and tributary, Hun river and Taizi river) 300 sampling sites of the algal community structure features and physical and chemical of water environmental factors were investigated, analysis algae community structure and physical-chemical characteristics of water environmental factors of each sample, and to use periphytic index of in integrity(P-IBI) and periphytic index of ecologica integrity(P-IEI) assessment ecosystem health the five stream segment in Liao river Basin, and then compare P-IBI and P-IEI applicability of the evaluation system. Results were shown as fllows:The periphyton species were diversity and the community structure were complex in Liao river Basin. A total of 95 species in 3 phylum were identified in Dongliao river, the average value of species richness, species density, Shannon-wiener index and pielou index is 10、1.86×104 ind/cm2、2.43 and 0.78, respectively; A total of 179 species in 4 phylum were identified in Xiliao river, the average value of species richness, species density, Shannon-wiener index and pielou index is 18、2.01×104 ind/cm2、2.89 and 0.78, respectively; A total of 180 species in 5 phylum were identified in Liao river and tributary, the average value of species richness, species density, Shannon-wiener index and pielou index is 21、0.21×104 ind/cm2、3.56 and 0.88, respectively; A total of 214 species in 3 phylum were identified in Hun river, the average value of species richness, species density, Shannon-wiener index and pielou index is 21、2.70×104 ind/cm2、3.27 and 0.78, respectively; A total of 173 species in 3 phylum were identified in Taizi river, the average value of species richness, species density, Shannon-wiener index and pielou index is 16、5.13×104 ind/cm2、3.03 and 0.79, respectively. For each section, Bacillariophyta was the dominant class, followed by Chlorophyta and then Cyanophyta. The periphytic algae community structure and spatial distribution had a significant difference in 5 stream-stretchs.Ecosystem integrity is the capability to support and maintain abalanced, Assessment of ecological integrity has great significance for preventing sensitive nature habitats from human disturbance. Each stream segment, combined with the feature of sample point and algae community structure choose not interfere site or interfere minimal site as a reference site. The results shown that, Dongliao river(E6, E15 and E17), Xiliao river(W23, W25 and W35), Liao river and tributary(L9, L56, L60 and L65), Hun river(H3, H11, H12, H36 and H54), Taizi river(T13, T37, T62 and T63). Selection 27 indicators of algae, 5 physical index and 8 chemical indicators of water environmental factors, according to the P-IBI and P-IEI system assessment each river health.The P-IBI results show that five stream segment aquatic ecosystem health is “good–general–good–general–good” for Dongliao river Xiliao river, Liao river and tributary, Hun river and Tizi river, respectively. However, The P-IEI results show that five stream segment aquatic ecosystem health is “good–good–general–good–good” for Dongliao river Xiliao river, Liao river and tributary, Hun river and Tizi river, respectively. The evaluation system of P-IBI and P-IEI correlation analysis showed that Dong laio river, Xiliao river, Liao river and tributary and Hun river had significant difference, the Taizi river had no-significant difference. Therefore, use P-IEI method to evaluate aquatic ecosystem health, theoretically more accurate evaluation of the integrity of ecosystems, is feasible.