title: Effects of sediment and turbulence on alkaline phosphatase activity and photosynthetic activity of phytoplankton in the shallow hyper-eutrophic Lake Taihu, China.
abstract: Sediments play important roles, as nutrient reservoir, especially in shallow lake ecosystem. The water column of large shallow lakes is often stable but also disturbed by turbulence causing resuspension of sediments. While considerable research has been carried out to investigate the influence of sediment resuspension on nutrient release, fewer studies have been done to understand the contribution of alkaline phosphatase activity (APA) in water as a response to the two conditions (turbulence and stability). Also, effects of the two lake conditions on photosynthetic efficiency of phytoplankton are still poorly understood. This study will evaluate the effect of these two conditions on photosynthetic efficiency and APA. Sediments used in the indoor experiments were collected from Zhushan Bay in Lake Taihu. Turbulence was generated by rotors to simulate the strong wind-induced disturbance in Lake Taihu. Results of the experiments showed that TN and TP in the stable and episodically turbulent conditions were not significantly different, with TN ranging from 1.34 to 1.90 mg/L and TP from 0.08 to 0.18 mg/L. Whereas, the soluble reactive phosphorus in the episodically turbulent condition was significantly higher than in the stable condition. Episodic turbulence could enhance P cycling by resuspending sediment-associated P, which alleviated algal P limitation. In stable conditions, P deficiency induced the production of high APA, which enhanced the availability of P. Although episodic turbulence could also cause increased algal biomass, photosynthetic efficiency of the algae was also affected not only by the nutrients but also by many other factors, especially light availability. Our results suggest that episodic turbulence is an important driver of biogeochemical cycling in large shallow hypertrophic lake ecosystem.
authors.affiliation: School of Resources and Geosciences, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, Jiangsu, China. qinbq@niglas.ac.cn.
authors.forename: Boqiang
authors.initials: B
authors.lastname: Qin
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, Jiangsu, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Xu
authors.affiliation: Fishery Machinery and Instrument Research Institute, Chinese Academy of Fisheries Sciences, Shanghai, 200092, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D018533:Biomass; D002681:China; D005068:Eutrophication; D019015:Geologic Sediments; D060106:Lakes; D010758:Phosphorus / Q000378:metabolism*; D010788:Photosynthesis; D010839:Phytoplankton / Q000201:enzymology*; D014919:Wind
chemical_list: D010758:Phosphorus; D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase activity; Phosphorus; Photosynthetic efficiency; Phytoplankton; Sediment resuspension