不同密度铜锈环棱螺对沉水植物生长和水质的影响

Effects of different densities of Bellamya aeruginosa on growth of submerged macrophytes and water quality

通过试验研究不同密度铜锈环棱螺(Bellamya aeruginosa)对苦草(Vallisneria natans)和金鱼藻(Ceratophyllum demersum)生长及水质的影响。试验结果表明:铜锈环棱螺的存在显著促进了沉水植物的生长,高密度组苦草和金鱼藻的相对生长率分别是对照组的2.16和1.66倍,高密度组苦草和金鱼藻的相对伸长率分别是对照组的1.18和1.25倍;铜锈环棱螺的存在对水质有一定负面影响,水体电导率随着螺密度的增加而升高,溶解氧浓度随着螺密度的增加而降低,pH值、氧化还原电位和叶绿素浓度随着螺密度的增加没有一致的规律;水体氮的去除率随螺密度的增加呈下降趋势,高密度组苦草和金鱼藻对氮的去除率相对于对照组分别下降了70.0%和64.5%,磷的去除率组间没有显著差异;铜锈环棱螺密度对水体氮浓度变化起主要作用,方差占比为64%,沉水植物不同物种对水体磷浓度变化起主要作用,方差占比为72.54%。

The effects of different densities of Bellamya aeruginosa on the growth of Vallisneria natans and Ceratophyllum demersum and water quality were studied through the experiment.The results showed that the presence of Bellamya aeruginosa significantly promoted the growth of submerged plants.The relative growth rates of Vallisneria natans and Ceratophyllum demersum in the high-density groups were 2.16 and 1.66 times of those in the control groups,respectively,and the relative elongation rates in the high-density groups were 1.18 and 1.25 times of those in the control groups,respectively.The existence of Bellamya aeruginosa had a certain negative impact on water quality.The water conductivity increased with the increase of snail density,and the dissolved oxygen concentration decreased with the increase of snail density.There was no consistent trend of pH value,redox potential and chlorophyll concentration with the increase of snail density.The removal rate of nitrogen in water showed a downward trend with the increase of snail density.The removal rates of nitrogen in the high-density group of Vallisneria natans and Ceratophyllum demersum decreased by 70.0%and 64.5%respectively compared with the control group.There was no significant difference in the removal rate of phosphorus between the groups.The density of Bellamya aeruginosa had the main effect on the variation of nitrogen concentration in water,with the proportion of variance of 64%,while the different submerged macrophytes played a major role in the change of phosphorus concentrations in water,with the variance proportion of 72.54%.