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Nitrogen and Phosphorus Metabolism in Lake Water/Mud Ecosystems and Ecological Succession as Factors responsible for Cyanobacterial Bloom.

湖水/泥生态系统中的氮和磷代谢以及生态演替是导致蓝藻水华的因素。

基本信息

批准号：
11680532
负责人：
SAKAMOTO Mitsuru
金额：
$ 2.18万
依托单位：
University of Shiga Prefecture, School of Environmental Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Field surveys and nutrient enrichment cultures were conducted for the North Basin to reveal the possible factors responsible for the development of cyanobacterila bloom in oligotrophic Lake Biwa, with a special reference to the nitrogen and phosphorus metabolism at lake water/mud interaction system and successional interaction in phytoplankton community.Based on my previous studies on the positive role of nutrients regeneration from the bottom sediments on development of cyanobacterial population, the field survey was focused on the sequential changes s of nitrogen and phosphorus in both lake water and phytoplankton. Pronounced decrease in nitrate concentration and noticeable increases in particulate nitrogen and cyanobacterial abundance were observed in association with increasing water temperature from late spring toward mid summer. These findings and a parallel decrease of dissolved organic nitrogen suggest the summer development of cyanobacterial population could be supported by ni … More trogen regeneration from dissolved organic matter through microbial activity at the lowest level of nitrate. Lowest nitrate condition is also effective to limit the growth of other algal species and permits the growth of cyanobacteria. In the nutrient enrichment cultures using the lake waters from the surface of the North Basin, significant positive effects on algal growth were observed for cyanobacterial population at higher temperature and external phosphorus enrichment, for green algae at nitrogen enrichment and for diatoms at lower temperature.These results imply that higher temperature and lower nitrate environment could be essential for the competitive development of cyanobacterial population and an external phosphorus supply to the water under this environment should stimulate the cyanobacterial growth. Lake water/sediments ecosystem at littoral zone of Lake Biwa is characterized by higher temperature and stimulated phosphorus liberation from the sediments during summer, and hence should provide the sites with frequent development of cyanobacterial bloom. Less

对北池进行了实地调查和营养物富集培养，以揭示导致琵琶湖贫营养蓝藻水华发展的可能因素，特别是湖水中氮和磷的代谢泥质相互作用系统和浮游植物群落演替相互作用的研究。在前人研究的基础上，探讨了底质营养盐再生对浮游植物群落发育的积极作用，蓝藻种群数量的变化，重点考察了湖泊水体和浮游植物中氮磷的动态变化。显着减少硝酸盐浓度和显着增加颗粒氮和蓝藻丰度观察到与水温从春末到盛夏。这些发现和溶解性有机氮的平行减少表明蓝藻种群的夏季发展可能受到镍的支持 ...更多信息在最低硝酸盐水平下，通过微生物活动从溶解的有机物中再生氮。最低的硝酸盐条件也有效地限制其他藻类的生长，并允许蓝藻的生长。在使用来自北部盆地表面的湖泊沃茨的营养物富集培养中，观察到在较高温度和外部磷富集下蓝藻种群对藻类生长的显著积极影响，这些结果表明，较高的温度和较低的硝酸盐环境可能是蓝藻种群竞争发展的必要条件，在这种环境下，向水中供应外部磷将刺激蓝藻生长。在夏季，琵琶湖沿岸的湖水/沉积物生态系统具有较高的温度和沉积物中磷的释放，是蓝藻水华频繁发生的场所。少