title: Analysis on biomass and productivity of epilithic algae and their relations to environmental factors in the Gufu River basin, Three Gorges Reservoir area, China.
abstract: The main purpose of this study conducted from August 2010 was to find biomass and productivity of epilithic algae and their relations to environmental factors and try to explore the restrictive factors affecting the growth of algae in the Gufu River, the one of the branches of Xiangxi River located in the Three Gorges Reservoir of the Yangtze River, Hubei Province, Central China. An improved method of in situ primary productivity measurement was utilized to estimate the primary production of the epilithic algae. It was shown that in rivers, lakes, and reservoirs, algae are the main primary producers and have a central role in the ecosystem. Chlorophyll a concentration and ash-free dry mass (AFDM) were estimated for epilithic algae of the Gufu River basin in Three Gorges Reservoir area. Environmental factors in the Gufu River ecosystem highlighted differences in periphyton chlorophyll a ranging from 1.49 mg m-2(origin) to 69.58 mg m-2(terminal point). The minimum and maximum gross primary productivity of epilithic algae were 96.12 and 1439.89 mg C m-2day-1, respectively. The mean net primary productivity was 290.24 mg C m-2day-1. The mean autotrophic index (AFDM:chlorophyll a) was 407.40. The net primary productivity, community respiration ratio (P/R ratio) ranged from 0.98 to 9.25 with a mean of 2.76, showed that autotrophic productivity was dominant in the river. Relationship between physicochemical characteristics and biomass was discussed through cluster and stepwise regression analysis which indicated that altitude, total nitrogen (TN), NO3--N, and NH4+-N were significant environmental factors affecting the biomass of epilithic algae. However, a negative logarithmic relationship between altitude and the chlorophyll a of epilithic algae was high. The results also highlighted the importance of epilithic algae in maintaining the Gufu River basin ecosystems health.
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China. gejiwen2002@aliyun.com.
authors: Jiwen
authors: J
authors: Ge
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.|Shanghai Waterway Survey and Design Institute Co. LTD, Shanghai, 200120, People's Republic of China.
authors: Shuyuan
authors: S
authors: Wu
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Dado
authors: D
authors: Touré
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Lamei
authors: L
authors: Cheng
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Wenjie
authors: W
authors: Miao
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Huafen
authors: H
authors: Cao
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Xiaoying
authors: X
authors: Pan
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Jianfeng
authors: J
authors: Li
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Minmin
authors: M
authors: Yao
authors: Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, Institute of Ecology and Environmental Sciences, School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, People's Republic of China.
authors: Liang
authors: L
authors: Feng
mesh_terms: D018533:Biomass; D002681:China; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis; D045483:Rivers / Q000737:chemistry*
chemical_list: D002734:Chlorophyll; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Ash-free dry mass (AFDM); Chlorophyll a; Energy flow; Epilithic algae; Primary productivity
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