Amechi S Nwankwegu1, Yiping Li2, Yanan Huang1, Jin Wei1, Eyram Norgbey1, Qiuying Lai1, Linda Sarpong1, Kai Wang1, Daobin Ji3, Zhengjian Yang3, Hans W Paerl4. 1. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China. 2. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China. Electronic address: liyiping@hhu.edu.cn. 3. College of Hydraulic and Environmental Engineering, Three Gorges University, Yichang, 443002, Hubei, China. 4. Institute of Marine Sciences, The University of North Carolina at Chapel Hill, Morehead City, NC, USA.
Abstract
The increasing freshwater ecosystem nutrient budget is a critical anthropogenic factor promoting freshwater eutrophication and episodic bloom of harmful algae which threaten water quality and public health. To understand how the eutrophic freshwater ecosystem responds in term of phytoplankton community structure dynamics to a sudden rise in nutrient concentrations, a microcosm study by nutrient addition bioassay was implemented in Xiangxi Bay (XXB) of Three Gorges Reservoir, China. Our results showed that dissolved trace elements supply adequately altered the phytoplankton community structure creating a regime shift from cyanobacteria-dominated to essentially Chlorophytes-dominated system, relative abundance (>70%). Combined N, P, and Si led to maximum growth stimulation accompanied by the highest chlorophyll yield (82.7 ± 14.01 μgL-1) and growth rate (1.098 ± 0.12 μgL-1d-1). N separate additions resulted in growth responses which did not differ while P -addition differed significantly (p∠0.05) with the control justifying a P limited system. Si enrichment stimulated diatom growth, relative abundance (20.62%) and maximum utility rate (USi = 83.37 ± 0.33%). This study also reveals that increasing nutrient loading from anthropogenic sources adequately decrease the ecological diversity (H < 1) and community overlap (CC ≤ 0.5) intensifying competition and succession which then select the fast-growing taxa to dominate and expand. Result points to the need for multiple nutrient control of N, P and Si loading into XXB through a prudent nutrient management protocol for lasting bloom mitigation in the tributary bay.
The increan class="Chemical">sing freshn class="Chemical">water ecosystem nutrient budget is a critical anthropogenic factor promoting freshwater eutrophication and episodic bloom of harmful algae which threaten water quality and public health. To understand how the eutrophic freshwater ecosystem responds in term of phytoplankton community structure dynamics to a sudden rise in nutrient concentrations, a microcosm study by nutrient addition bioassay was implemented in Xiangxi Bay (XXB) of Three Gorges Reservoir, China. Our results showed that dissolved trace elements supply adequately altered the phytoplankton community structure creating a regime shift from cyanobacteria-dominated to essentially Chlorophytes-dominated system, relative abundance (>70%). Combined N, P, and Si led to maximum growth stimulation accompanied by the highest chlorophyll yield (82.7 ± 14.01 μgL-1) and growth rate (1.098 ± 0.12 μgL-1d-1). N separate additions resulted in growth responses which did not differ while P -addition differed significantly (p∠0.05) with the control justifying a P limited system. Si enrichment stimulated diatom growth, relative abundance (20.62%) and maximum utility rate (USi = 83.37 ± 0.33%). This study also reveals that increasing nutrient loading from anthropogenic sources adequately decrease the ecological diversity (H < 1) and community overlap (CC ≤ 0.5) intensifying competition and succession which then select the fast-growing taxa to dominate and expand. Result points to the need for multiple nutrient control of N, P and Si loading into XXB through a prudent nutrient management protocol for lasting bloom mitigation in the tributary bay.
Authors: Linda Sarpong; Yiping Li; Eyram Norgbey; Amechi S Nwankwegu; Yue Cheng; Salifu Nasiru; Isaac Kwesi Nooni; Victor Edem Setordjie Journal: Int J Environ Res Public Health Date: 2020-06-11 Impact factor: 3.390