| 摘要: |
| 富营养化是水生态系统主要的环境问题，自然条件下多种营养盐以组合形式进入水体，明确浮游植物群落对多种营养盐加富的响应对富营养化防治有重要意义。本研究以一座华南热带水库为例（大沙河水库），分析了2021年枯水期（1~3月）和丰水期前期（4~6月）氮（N）、磷（P）、铁（Fe）和叶绿素a（Chl.a）浓度的变化趋势，并通过原位添加实验，解析浮游植物丰度和多样性对N、P、Fe加富的响应。结果表明：与1~3月相比，4~6月期间水体总P浓度（TP）明显升高，总Fe浓度（TFe）呈增加趋势但月度间波动较大，总N浓度(TN)在4月最低，之后缓慢增加，期间Chl.a浓度从3月的5 μg/L快速增加到5月的29 μg/L。原位实验结果表明：浮游植物群落以蓝藻、绿藻和硅藻为主要组成，所有营养盐添加组浮游植物丰度均有增加，但只有NP同时添加时（NP和FeNP两组）生物量（以Chl.a指示）有显著升高；添加条件下细胞丰度的响应在门类和种类间差异明显，实验组组间群落结构和优势种类差异显著，所有处理组的群落多样性均明显高于对照组。N和P添加及其与Fe的联合添加（N、P、NP、FeN、FeP和FeNP）均导致蓝藻丰度升高，绿藻仅在NP添加组（FeNP组和NP组）显著升高且两组没有显著差异，硅藻仅在N和P单独添加组（N和P）显著升高。上述结果说明浮游植物生物量受N、P营养盐的共同影响而非单因子作用，N、P和Fe添加均影响群落结构和多样性，对水库富营养化的管理尤其是蓝藻水华防治应综合考虑3种营养盐的共同作用。 |
| 关键词: 氮 磷 铁 浮游植物 群落结构 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金、中国科学院野外站联盟项目和蓝藻水华应急处置技术示范研究, |
|
| Responses of phytoplankton communities to N-P-Fe enrichments in wet season of tropical reservoir in Southern China : A case study of Dashahe Reservoir, Guangdong Province |
|
Xie Jing,Su Yuliang,Wu Bing,Zhang Yi,Xiao Lijuan,Gu Jiguang
|
|
Department of Ecology, Jinan University, Guangzhou
|
| Abstract: |
| Eutrophication is one of the main threats to aquatic ecosystems, and various nutrients combined flow into water. Tt is important to understand the response of phytoplankton community to enrichment of multiple nutrients for eutrophication control. To elucidate the response of phytoplankton community to three essential nutrients (N, P and Fe) in tropical reservoirs of Southern China, we analyzed the variation of N, P, Fe and Chl.a in a typical reservoir (Dashahe Reservoir) from dry seasaon (January - March) to wet season (April - June) 2021. An in-situ experiment was conducted to clarify the responses of phytoplankton abundance and diversity to the N, P and Fe enrichment. Compared with the conditions during January - March, the total phosphorus concentration increased significantly from April to June, the total Fe concentration showed an increasing trend but fluctuated greatly among months, total nitrogen concentration arrived at the lowest value in April then increased slowly. Accompanied with the variation of nutrients, Chl.a concentration increased from 5 μg/L in March to 29 μg/L in May. The results of in-situ enrichment experiment showed that cyanobacteria, chlorophyta and diatom were the main compositions of phytoplankton. The increase in phytoplankton abundance was observed in all treatments, but only the combined addition of both N and P (NP and FeNP) caused significant increase of biomass (indicated by Chl.a concentration). The abundance responses to the same nutrient addition were different among phyla and species, and community structure and dominant species were significant differences among treatments. The community diversity of treatments pronounced higher than control. Cyanobacteria abundance increased in all of the treatments (N, P, NP, FeN, FeP and FeNP) except the treatment of single Fe addition, chlorophyta abundance significantly increased in NP and FeNP treatments while no significant difference was observed between these two treatments, and abundance of diatom significantly increased (P< 0.05, ANOVA) in single addition of N and P treatments. These results suggested that phytoplankton abundance was primarily limited by N and P. Therefore, the increase in abundance depends on the synergistic rather than the single effect of nutrients. The any addition of N, P and Fe can affect community structure and diversity. Our study implied that eutrophication management, especially controlling cyanobacteria blooms, should consider the synergistic effect of N, P and Fe. |
| Key words: nitrogen phosphorus iron phytoplankton community structure |
