不同水动力条件下的河流硅藻群落分布机理研究

Study on distribution mechanism of riverine diatoms community in different hydrodynamic conditions

水体生物种群指标与河流水动力参数之间的关系是水生态的重要研究课题之一。在西江水系柳江河流共设置31个硅藻采样点,来探究表层沉积硅藻在不同水动力条件下的群落结构,着重研究了硅藻与水深、流速和流量等水文变量间的关系。在研究区域共发现硅藻2纲38属264种,通过层状图和排序分析,流速是影响硅藻群落分布最主要的水动力条件,其次才是雷诺数。雷诺数的大小和浮游种类丰度关系紧密,但雷诺数对硅藻种类的影响还有不确定因数。直链藻和小环藻等浮游种类在大江中比小溪中较易出现,同时人工修建的大坝通过改变水动力条件,对藻类的分布产生影响,尤其在水库下游等较极端的湍流条件下,桥弯藻和脆杆藻的丰度明显地增长。

The relationship between biological indicators of water body and hydrodynamic parameters of river is one of the important research subject of aquatic ecosystem. The paper set 31 diatom sampling points at Liujiang river to explore the community structure of surface sediment diatoms under different hydrodynamic conditions and focused on relationship between diatoms and hydrological variables such as water depth,velocity and flow. The diatoms found in the study area are 264 kinds of 2 classes 38. Through layered diagrams and sequence analysis,the flow rate is the most important hydrodynamic condition that influences diatom community distribution,followed by the Reynolds number. The relation between the size of Reynolds number and abundance of planktonic species is close,but the influence of Reynolds number on diatom species is also uncertain. Planktonic species such as Melosira and Cyclotella more easily appear in the river than in the creek,while artificial dam changes the hydrodynamic conditions and has impact on the distribution of algae,especially in the downstream reservoir and other more extreme turbulence conditions,the abundance of cymbella and fragilaria show a growth trend.