Loading...
Please wait, while we are loading the content...
Similar Documents
Decline of Microcystis aeruginosa FACHB-905 under four stress conditions
| Content Provider | Semantic Scholar |
|---|---|
| Author | Jie, Li Danyun, Ou Lirong, Song |
| Copyright Year | 2008 |
| Abstract | The present study aimed to evaluate the contribution of stress factors to the decline of Microcystis bloom, also tried to develop some indicator of decline. Four stress conditions including nitrogen starvation, phophorus starvation, dark and low temperature (10°C) were designed. Decrease of biomass and the concomitant change of antioxidant system, including superoxide dismutase (SOD) and catalase (CAT) activities were detected. The result indicated that growth was significantly inhibited under dark and low temperature. Microcystis population declined after 25 days under dark, while declined after only 7 days under low temperature. Compared with the physical stress, nutrition such as nitrogen and phosphorus did not limit the growth effectively in the early stage. Chlorophyll-a decreased as soon as being incubated into nitrogen free BG-11 medium. After being kept in phosphorus free medium for 20 days, chlorophyll-a reached peak, about the twice of the initial concentration, and then decreased at a rate of 0.1mg/(L·d), which was the highest decaying rate among the four factors. It indicated its significance of available phosphorus for Microcystis survival and decline. According to the results, when phosphorus was limited, or water temperature was decreased to 10°C, cautions should be taken into account for the decrease of dissolved oxygen and possible increase of toxins or odors substances from * 国家高技术研究发展计划 863 项目(2005AA60101005)和中国科学院知识创新工程重要方向项目(KZCX2-YW-426)联合 资助. 2007-12-11 收稿; 2008-01-15 收修改稿. 李杰, 男, 1982 年生, 博士研究生, E-mail: lijie@ihb.ac.cn. ** 通讯作者; E-mail: lrsong@ihb.ac.cn. J. Lake Sci.(湖泊科学), 2008, 20(5) 550 the declining bloom. In healthy Microcystis, SOD activity was about 0.06U/mg protein, while CAT activity was too low to be measured. In addition, SOD activity increased earlier than CAT activity when Microcystis was exposed to stress conditions. CAT activity increased only when the content of chlorophyll-a began to decline. Both of the increase of SOD and CAT activities correlated negatively with the decrease of the content of chlorophyll-a though there were some exceptions. Combination of the two parameters would be potential indicator of bloom decline. Keyword: Microcystis; decline; stress; prediction; antioxidant system 有毒蓝藻水华作为世界范围内的热点问题, 目前主要集中于研究水华的发生及危害, 有关水华消失 的过程, 人们知之甚少. 事实上, 浮游植物的衰亡对环境的影响与大量生长对环境的影响同等重要. 浮游植物死亡后, 释放的有机质, 特别是碳源的提供, 会引发新一轮的资源竞争和种群演替, 水体 生态系统发生动态改变. 在棕囊藻(Phaeocystis)死亡后, 异养细菌对浮游植物衰亡所引发的环境改变做 出了快速响应, α-变形菌纲和拟杆菌门立即出现, 原生动物生物量也剧增. 浮游植物的下沉还会促进 底栖生物的消化系统消化能力, 引起食物网传递链的改变. 第二, 在细菌作用下, 死亡藻细胞被降解, 水体有机质含量急剧增加, 也导致水体溶氧的急剧下降, 使水体中对低溶氧敏感的生物窒息而亡, 造成 巨大经济损失. 溶氧偏低常常是水华水体中鱼类死亡的主要原因, 对低溶氧的敏感程度不同, 导致鱼 类种群大小、年龄结构及多样性发生改变; 覆盖在水体底部的藻细胞, 还会损坏水体间隙水水质, 进 而影响到鱼类产卵. 第三, 浮游植物死亡后, 部分有害代谢产物从细胞内溢出, 如肝毒素(Microcystin), 异味物质等会损害水质, 增加自来水处理负担的同时, 对动物和人类健康造成威胁. 影响水华消失的因素有很多, 传统的观点认为, 浮游动物的捕食, 浮游植物本身不可逆的下沉对浮 游植物生物量下降的贡献最大. 近来细菌、病毒、真菌引起浮游植物生物量的下降也逐渐受到关注. 在浮游植物生物量达到高峰期时, 所产生的营养胁迫, 以及暴露在光、温度和毒素物质的极端条件下, 也 有可能引起细胞死亡. 本研究中, 在实验室条件下设计了氮饥饿、磷饥饿、黑暗、10°C低温等四种胁迫条件, 研究微囊藻对 这些不利条件的耐受能力及在胁迫作用下的衰亡过程, 进而判断这些不利条件对水华消失的可能贡献做 出评价. 就微囊藻抗氧化酶系统在四种胁迫条件的变化进行了着重研究, 对SOD和CAT能否用于指示微 囊藻群体的衰亡趋势进行了探讨. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jlakes.org/ch/reader/create_pdf.aspx?file_no=20080501&flag=1&quarter_id=5&year_id=2008 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
