不同营养水平下苦草对附着和浮游藻类的影响

通过室内培养,研究了不同营养盐浓度下苦草对附着藻类和浮游藻类的影响,同时比较了两种藻类对不同营养盐浓度的响应,结果发现附着藻类在中高营养盐浓度下生物量较高而浮游藻类在中低营养盐浓度下生物量较高,虽然两者对营养盐的响应不一致,但其最大量都出现在中高浓度的营养盐状态下。在中低营养盐浓度下(ρTN=0.4～2.5mg/L),苦草促进附着藻类而抑制浮游藻类,即相比于浮游藻类而言,附着藻类对苦草的敏感性较低。在较高营养盐浓度(ρTN=4.5～6.5mg/L)下,苦草对附着藻类产生了极显著的抑制作用,且这种抑制作用随着营养盐浓度的增加而增强,在ρTN=6.5mg/L的处理条件下,苦草对附着藻类的抑制率近80%,但是在此营养盐浓度处理下,苦草对浮游藻类的抑制作用却减弱甚至消失了。

Effect of Vallisneria natans on Periphytic Algae and Phytoplankton with Different Nutrients

Effects of Vallisneria natans on periphytic algae and phytoplankton in water with different nutrient treatments and responses of periphyton and phytoplankton to the nutrient concentration were studied in laboratory.Studies showed that the periphyton biomass were higher with oligo-mesotrophic treatment while the phytoplankton biomass were higher under oligotrophic treatment,although their responses to nutrient were not the same,their highest biomass were both under oligomesotrophic condition.Under the nutrient of total nitrogen between 0.4mg/L and 2.5mg/L,V.natans facilitated the growth of periphyton and inhibited the phytoplankton,periphyton was less sensitive than phytoplankton to submersed macrophytes in water.Under the nutrient of total nitrogen between 4.5mg/L and 6.5mg/L,V.natans caused a significant inhibition on periphytic algae,and the inhibition strengthened by enhance of nutrient concentration.When total nitrogen of treatment was 6.5mg/L,rate of inhibition on the periphyton by V.natans was 80%,while the inhibition on the phytoplankton declined even lost under the nutrient treatment.