河流中浮游藻类生长的可能影响因素研究进展与展望

Possible influencing factors on phytoplankton growth and decay in rivers:review and perspective

河流富营养化问题日益严重,尽管湖泊中富营养化机理已被研究得较为透彻,但是针对河流中藻类大量生长的机理研究还较为缺乏。可能影响河流中浮游藻类生长的因素包括营养盐、光照、温度、水动力条件和动物捕捉等,本文系统调研了相关的研究进展,归纳分析了河流与湖泊两个生态系统的区别。总结发现影响河流浮游藻类生长的限制因素与湖泊不尽相同,比如尽管营养盐被认为是湖泊浮游藻类生长的主要限制因素,但在河流中影响不明显;而水体冲刷和相应带来的光强改变对于河流中的藻类生长有重要影响;河流中浮游藻类的被捕食压力弱于湖泊。目前多数生态模型都是基于湖泊中藻类生长进行开发,所以将这类生态模型应用于河流时需根据上述特征进行调整。综观目前的研究成果,水动力及水体中光强分布对于浮游藻类的生长影响是未来的研究重点,而上游有富营养化湖泊的河流可以作为一个特殊案例进行研究。

River eutrophication is a serious problem nowadays. Although the mechanism of eutrophication in lakes is relatively well understood, the previous studies on how blooms develop in rivers are quite limited. This paper presents a review on the studies concerning influencing factors on phytoplankton in rivers, such as nutrients, light intensity, temperature, hydrodynamics, and grazing. Large differences exist between rivers and lakes. It seems that the main limiting factor of phytoplankton growth in lakes is nutrient salt while the factor in rivers is flushing rate and in consequence changes of light penetration. Besides, neither grazing nor temperature is so important to a river as to a lake. We can take a special case, rivers downstream of eutrophic lakes, as an example for analysis on the differences between these two kinds of water ecosystems and their corresponding phytoplankton succession. Considering their derivation based on the mechanism of eutrophication in lakes, most of the existing ecological models should be modified according to the differences aforementioned before being applied to rivers. This review and analysis suggests that to improve our understanding of phytoplankon growth in rivers, the impact of hydrodynamics and light penetration should be further studied. Among them, a unique case worthy special attention is about phytoplankton growth and decay in rivers downstream of eutrophic lakes.