Ning Man, Li Huimin, Xu Zheng, Chen Lei, He Yiliang
China-UK Low Carbon College, Shanghai Jiao Tong University, 3 Yinlian Road, Shanghai 201306, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
Ecotoxicol Environ Saf. 2021 Jun 15;216:112216. doi: 10.1016/j.ecoenv.2021.112216. Epub 2021 Apr 11.
Understanding picophytoplankton variations that play important roles in the material circulation and energy flow are critical to assessing overall status of waterbody, especially for clean reservoirs which remain a relatively stable community structure and high species diversity due to lower nitrogen and phosphorus nutrients. However, their response to key environmental factors and tightly acting microbial remains poorly understood. Traditional quantification methods are limited, such as chlorophyll-a, turbidity and microscope. There are still many defects with present molecular analysis. In this study, a flow cytometric analysis and high-throughput sequencing combination methodology was developed and tested on clean water from a reservoir, by a monthly dynamic for a vegetative period April-September in 2019 to improve the accuracy of dynamic monitoring for the picophytoplankton system. More species of Pico-Cyanobacteria and Pico-Eukaryotes were discovered. The increased percentage of pigment compounds from 8.2% to 76.3% proves the effective reduce of heterotrophic disturbing and enrichment of target populations. Picophytoplankton that was previously neglected due to their low relative abundance has once again entered the scope of our eyes. Phytoplankton were divided into three categories. The first one was the highly abundant and frequently present taxa, the second one was the low-abundance but highly-transient population, and the third one was the low abundance and stable group. Synechococcus, Emiliania, Tetraselmis and Thalassiosira were dominant picophytoplankton and displayed obvious temporal and spatial distribution characteristics. Pico-PE rich Cyanobacteria and Nano-Eukaryotes with high transience abnormally increased in summer. Temperature, ammonia-N, nitrate-N, turbidity and total nitrogen were most influencing factors, while some picophytoplankton with special physiological structure showed distinct competitive advantages in the microbial community. As for the off-flavor compounds, the concentration of 2-methylisoborneol and geosmin were high even 66.7% and 20.8% of the samples exceeded their olfactory threshold. Chrysochromuina, Planktothrix and Microcystis might be the potential producers.
了解在物质循环和能量流动中发挥重要作用的微微型浮游植物的变化，对于评估水体的整体状况至关重要，特别是对于清洁水库而言，由于氮磷养分含量较低，其群落结构相对稳定，物种多样性较高。然而，它们对关键环境因素的响应以及与紧密作用的微生物之间的关系仍知之甚少。传统的量化方法存在局限性，如叶绿素a、浊度和显微镜观察等。目前的分子分析仍存在许多缺陷。在本研究中，开发了一种流式细胞仪分析和高通量测序相结合的方法，并于2019年4月至9月的植物生长季节每月动态地对水库中的清洁水进行测试，以提高微微型浮游植物系统动态监测的准确性。发现了更多种类的微微型蓝细菌和微微型真核生物。色素化合物的比例从8.2%增加到76.3%，证明了异养干扰的有效减少和目标种群的富集。以前因相对丰度较低而被忽视的微微型浮游植物再次进入我们的视野。浮游植物分为三类。第一类是高丰度且频繁出现的类群，第二类是低丰度但高瞬态的种群，第三类是低丰度且稳定的类群。聚球藻属、艾氏藻属、四爿藻属和海链藻属是主要的微微型浮游植物，呈现出明显的时空分布特征。富含微微型真核生物的蓝细菌和具有高瞬态性的纳米真核生物在夏季异常增加。温度、氨氮、硝态氮、浊度和总氮是最具影响的因素，而一些具有特殊生理结构的微微型浮游植物在微生物群落中表现出明显的竞争优势。至于异味化合物，2-甲基异莰醇和土臭素的浓度很高，甚至66.7%和20.8%的样本超过了它们的嗅觉阈值。金黄藻属、席藻属和微囊藻属可能是潜在的产生者。
