Study On The Habitat Characteristics And Ralated Environmental Factors Of Hampala Macrolepidota

Hampala macrolepidota belongs to the genera of Hampala, in the subfamily Barbinae, the family Cyprinidae, and the order Cypriniformes. It has been placed on the endangered-species lists of “Endangered in China Red Data Book of Endangered Animals-Pisces”. With the influence of human activities, environment in Nanla River region was damaged in recent years. Aquatic biodiversity and habitats of Hampala macrolepidota were under serious challenges. Researches on Hampala macrolepidota’s habitats and its relationships with water quality and plankton were very important for the protection of Hampala macrolepidota in Nanla River region. The main results are as follows:1. The water quality of Lan-cang River(Xishuangbanna section) was the best of these areas, followed by Liu-sha River and Nan-a River with lower level of dissolved oxygen in part of sampling sites than the standard. Whereas DO of all sampling sites in Nan-la River and Luo-suo River did not meet the standard of study areas, NH3-N of few sampling sites in Nan-la River and Luo-suo River were beyond the standard of study areas, TN of all sampling sites in Nan-la River exceeded the standard of study areas. Based on classifications of the water quality using cluster analysis, the surveyed rivers could be divided into three categories. One was the good water quality river like Lan-cang River(Xishuangbanna section). The second category had lower water quality level, such as Liu-sha River and Nan′a River. The third category had poor water quality like Luo-suo River and Nan-la River. Results of principal component analysis showed that Tur, EC, WT, NH3-N, DO and p H were the main factors which could reflect the water quality state in study areas. Tur of Lan-cang River(Xishuangbanna section) in different hydrological periods was much lower than that of other rivers, and Tur of Liu-sha River and Nan-a River had shown great seasonal variations. Tur of Nan-la River in flood season was significantly higher than turbidity in dry season and average season and the spatial distributions of Tur were very uneven. Lan-cang River(Xishuangbanna section) had the highest EC while Liu-sha River and Nan-a River had the lowest EC. EC of Nan-la River in flood season was significantly higher than that in dry season and average season. The highest of NH3-N was in Nan-la River, followed by Luo-suo River, Liu-sha River, Nan-a River and Lan-cang River(Xishuangbanna section). WT, DO and p H had not shown significant differences in temporal and spatial in this research.2. Cyanophyta was dominant population in the upstream while Bacillariophyta was dominant population in the downstream. The cell density of phytoplankton did not change significantly between the seasons,but showed extremely significant difference in spatial distribution. It was found that the water body of Nanla River belonged to α/β-ms type compared the phytoplankton biodiversity index. Results of principal component analysis and canonical correspondence analysis indicated that TN was likely to be a limiting factor for the growth of phytoplankton in the rainy season. And WT was the main factor affecting phytoplankton in the dry season. Meanwhile Tur and SS were inhibitory effect on the density of phytoplankton in the dry season. Protozoans were dominant population in the most reaches of Nanla River, especially in the downstream river. Rotifers had most species and the contribution of Cladocera was much lower than protozoa, Rotifers and copepods. The density of zooplankton did not change significantly between the seasons,but showed extremely significant difference in spatial distribution. Results of principal component analysis and canonical correspondence analysis indicated that p H and Chl-a were the the main factors affecting zooplankton in the rainy season, DO and WT were likely to be the limiting factors for the growth of zooplankton in the rainy season. And TP was the main factor affecting zooplankton in the dry season.3. Hampala macrolepidota was mainly concentrated in Dasha Dam Reservoir and Jinfeng Reservoir. It was also founded in the vicinity of Mengha Bridge which was in the middle river and the downstream of Dasha Dam Reservoir and Jinfeng Reservoir. The capture quantity of Hampala macrolepidota in the former region was larger than the latter regions. It was not found traces of Hampala macrolepidota in the other sections. Results of habitat evaluation showed that comprehensive evaluation index of distributions of Hampala macrolepidota was between 106 and 165, with an average of 130. Habitat quality of Hampala macrolepidota in Nanla River was good. Results of correlation analysis showed that phytoplankton density, habitat complexity, channel alteration and capture quantity of Hampala macrolepidota were significantly positively correlated. Velocity-depth combination, intensity of human activities and capture quantity of Hampala macrolepidota were significantly negatively correlated. Substrate, habitat complexity, velocity-depth combination and channel alteration were the main indexes of habitat quality assessment. Conductivity, Water Temperature, Turbidity, Suspended Solids and Total Nitrogen were easily influenced by the changes of river habitat quality. And the abundance of phytoplankton was easily influenced by the vegetation diversity of the river bank.