不同种植密度苦草与铜绿微囊藻的交互作用

Interaction between Vallisneria natans with Different Planting Density and Microcystis aeruginosa

沉水植物能有效抑制蓝藻水华,通常以铜绿微囊藻为主要优势物种,但沉水植物与铜绿微囊藻相互抑制效应是否取决于沉水植物的种植密度还需进一步探究。该研究采用透析袋方法对苦草(1000、1500、2000 g/m^(3))3种种植密度与铜绿微囊藻(8×10^(4)、4×10^(5)、8×10^(5)cells/mL)形成共培体系,并对生物量、光合损伤进行分析。研究结果表明,当铜绿微囊藻密度为8×10^(4)cells/mL时,种植1000 g/m^(3)苦草对铜绿微囊藻的抑制效果高达91.73%,同时较对照组铜绿微囊藻的Chl-a含量、光合活性Fv/Fm分别降低了93.81%、63.87%,藻蓝蛋白受到严重损伤。当铜绿微囊藻密度为4×10^(5)、8×10^(5)cells/mL时,种植1500 g/m^(3)苦草对铜绿微囊藻的抑制率分别为43.70%、34.99%,较对照组其Chl-a含量分别降低了67.39%、44.27%,光合活性Fv/Fm分别降低了29.10%、48.58%。相对于苦草而言,1000 g/m^(3)苦草种植密度组在4×10^(5)、8×10^(5)cells/mL的铜绿微囊藻密度中其生物量较对照组分别降低了30.36%、35.71%,同时Chl-a含量、光合活性Fv/Fm和Y(Ⅱ)值都降低,光合活性均受到抑制。而随铜绿微囊藻密度增加到4×10^(5)、8×10^(5)cells/mL时,种植1500 g/m^(3)苦草抑藻效果大于2000 g/m^(3)苦草种植,且自身受损程度小。这表明湖泊生态系统控藻及恢复沉水植物过程中,物种间的相互抑制作用具有一定的密度依赖性。在后期防治蓝藻水华过程中,建议合理规划沉水植物种植密度以达到较好的修复效果。

Submerged macrophytes can effectively inhibit cyanobacteria bloom,which are dominated by Microcystis aerugi-nosa.However,whether the inhibitory effect of submerged macrophytes on M.aeruginosa depends on its density needs further investigation.In this study,dialysis bag method was used to form a co-culture system between Vallisneria natans(Lour.)Hara with three densities(1000 g/m^(3),1500 g/m^(3),2000 g/m^(3))and M.aeruginosa with 8×10^(4)cells/mL,4×10^(5)cells/mL,8×10^(5)cells/mL.The biomass,photosynthetic damage were analyzed.The results showed that when the M.aeruginosa density was 8×10^(4)cells/mL,the inhibition effect of V.natans Lour.with 1000 g/m^(3) was decreased by 91.73%,and the content of Chl-a and photosynthetic activity Fv/Fm of M.aeruginosa were decreased by 93.81%and 63.87%,respectively,compared to the control.Phycocyanin is severely damaged and has low engineering cost.When the M.aeruginosa density was 4×10^(5)cells/mL and 8×10^(5)cells/mL,the inhibition rates of M.aeruginosa by V.natans Lour.with 1500 g/m^(3) were 43.70%and 34.99%,respectively,and the content of Chl-a decreased by 67.39%and 44.27%,respectively,compared to the control.The photosyn-thetic activity Fv/Fm was decreased by 29.10%and 48.58%.Compared with V.natans Lour.,in the algae-grass coculture group with the planting density of 1000 V.natans Lour.,the biomass of M.aeruginosa decreased by 30.36%and 35.71%in group of 4×10^(5)cells/mL and 8×10^(5)cells/mL M.aeruginosa,respectively,compared to the control,and the Chl-a content of V.natans Lour.was inhibited.Photosynthetic capacity decreased significantly.At the same time,photosynthetic activity Fv/Fm and Y(Ⅱ)values decreased with the increase of M.aeruginosa density.When the density of Microcystis aeruginosa in-creased to 4×10^(5)cells/mL and 8×10^(5)cells/mL,when the density of M.aeruginosa density was increased to 4×10^(5)cells/mL and 8×10^(5)cells/mL,planting of Vallisneria natans Lour.1500 g/m^(3)could achieve better algal inhibition effect,and the damage de-gree was small.This indicates that the mutual inhibition between species in the process of M.aeruginosa control and sub-merged plant restoration in lake ecosystems is density-dependent.In the process of controlling cyanobacteria bloom in the later stage,it is suggested that reasonable planning of planting density of submerged plants can achieve better restoration effect.