Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
Chemosphere. 2020 May;247:125960. doi: 10.1016/j.chemosphere.2020.125960. Epub 2020 Jan 20.
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) and growth rate (1.098 ± 0.12 μgLd). 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 (U = 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.
不断增加的淡水生态系统营养物预算是促进淡水富营养化和有害藻类爆发的人为关键因素，这些因素威胁着水质和公共健康。为了了解富营养化的淡水生态系统如何在浮游植物群落结构动态方面对营养物浓度的突然升高做出反应，我们在中国三峡水库的香溪河（XXB）进行了添加营养物的生物测定微宇宙研究。我们的结果表明，溶解微量元素的充分供应改变了浮游植物群落结构，导致从蓝藻为主向以绿藻为主的系统发生了转变，相对丰度（>70%）。综合氮、磷和硅的添加导致了最大的生长刺激，伴随着最高的叶绿素产量（82.7±14.01μg/L）和生长率（1.098±0.12μg/L/d）。氮的单独添加导致的生长响应没有差异，而磷的添加则与对照有显著差异（p∠0.05），这证明了磷限制系统的存在。硅的富集刺激了硅藻的生长，相对丰度（20.62%）和最大利用速率（U=83.37±0.33%）。本研究还表明，人为来源的营养物负荷增加会充分降低生态多样性（H<1）和群落重叠（CC≤0.5），加剧竞争和演替，从而选择快速生长的分类群来占主导地位和扩张。结果表明，需要通过谨慎的营养物管理方案来控制 XXB 中氮、磷和硅的多种营养物负荷，以持久缓解支流入湖的富营养化问题。
