摘要
Abstract
Eutrophication is a serious threat to water supply safety and ecological security.Eco-restoration, such as planting submerged macrophytes, can control eutrophication effectively and water depth is an important factor affecting the growth and distribution of submerged macrophytes.Thus, studying the effect of water depth on the growth of submerged macrophytes would benefit efforts to control eutrophication.The main purpose of this study was to investigate the growth response of Vallisneria natans (V.natans) to different water depth in an enclosure study.From June 15 to July 27, 2015, a pot experiment was conducted in the northern area of Taihu Lake.Pots were held in stainless steel frames suspended from floats at different depths (D1=1.0 m, D2=1.5 m and D3=2.0 m).During the 45 day experiment, samples were collected once a week for measurement of total nitrogen, total phosphorus, cyanobacteria density, and growth parameters of V.natans.No significant differences were observed in TN, TP or cyanobacteria among the three groups (P>0.05) and water depth was the key factor affecting growth of V.natans.Survival rate, tiller number and average blade length varied by group.Survival rate of V.natans decreased with increasing water depth and the survival rate at D1 was significantly higher than at D2 and D3 (P<0.05).From day 7 to the day 28, the survival rates at D1, D2 and D3 decreased, respectively, from 91% to 64%, 30% to 9% and 27% to 5%.In the early stage of the experiment, the average blade length of V.natans decreased with increasing depth, and blade breakage occurred in group D1 near the end of the experiment.From day 14 to day 28, average length of the leaves in D1 decreased from 10.3 cm to 4.46 cm, a 57% reduction and tillering was only observed in group D1.Our study indicates that the restoration of V.natans is best carried out at water depths of less than 1.0 m and it is necessary to reduce the influence of wind, waves and cyanobacteria blooms on the growth of submerged macrophytes using wave attenuations and soft enclosures.关键词
苦草/水深/原位试验/太湖Key words
Vallisneria natans/water depth/in situ enclosure/Taihu Lake分类
生物科学
