富营养水体中沉水植物与浮游藻类相互竞争的研究

STUDIES ON THE INTERACTION OF SUBMERGED PLANT AND PHYTOPLANKTON IN EUTROPHIC WATERS

本文就沉水植物与浮游藻类在富营养水体中的相互竞争现象及机制作了初步研究。室内外实验结果表明,二者之间存在着复杂的相互竞争关系。在光资源竞争上,浮游藻类占有相对优势;对水中营养盐的竞争是单向的,沉水植物因可以从底泥中得到营养盐而处于优势地位;当光照和营养盐充足时沉水植物对浮游藻类有明显的生化抑制效应,这种抑制可能通过促进藻类沉降而起作用。二者的互竞争受水深、水温及水中营养盐含量的强烈影响,高水温、高营养盐含量及深水均不利于沉水植物,而助长了浮游藻类的竞争优势。沉水植物群落一旦形成较大的密度,就能对浮游藻类产生强烈的抑制,保持自己的优势地位。因此,沉水植被恢复应从水温和水位均较底的冬季开始,严格控制营养盐输入量是非常重要的。

Experimental studies on the interaction of submerged plant and phytoplankton in an eu-trophic lake revealed complex mutual inhibition competition. Keen competition for the light in the water was found and phytoplankton took remarkable dominance. Submerged plant was the stronger competitor for mineral nutrients because it could get nutrients from both the lake water and the fertile sediment at the bottom. When light and nutrients were abundant, phytoplankton was suppressed by submerged plant with some unknown biochemical which caused falling of phytoplankton. The competition equilibrium was obviously affected by water depth, water temperature and nutrient concentration in the water. Phytoplankton would prefer high temperature, deep water and high nutrient level, but submerged plant the opposite. Once the community of submerged plant grew up, it gave stronger suppression to the phytoplankton and kept its dominance more stable. Thus, submerged plant should be planted in the cool and low water level season in eutrophic waters with the external nutrient source strictly controlled.