盐龙湖沉水植物群落变化规律及其驱动因子研究

为探究沉水植物群落现状及其变化规律，2015年10月至2019年10月对江苏省盐龙湖沉水植物进行连续跟踪调查，并分析沉水植物生长和分布的主要驱动因子。结果表明，调查期间共记录沉水植物15种，隶属于1门、6科；其中2015-2019年沉水植物出现种类数分别为13、12、9、11、12种。从优势种变化来看，沉水植物优势种整体经过穗状狐尾藻（Myriophyllum spicatum）→金鱼藻（Ceratophyllum demersum）→马来眼子菜（Potamogeton malaianus）→穗状狐尾藻的变化过程。从覆盖度和生物量变化看，盐龙湖沉水植物的覆盖度和生物量均呈现先下降、后上升的变化趋势，其中2016-2017年沉水植物退化显著，但随着生态修复措施的进行，2018-2019年沉水植物群落逐渐恢复。相关分析表明，沉水植物生物量与透明度显著正相关（P <0.05），与浊度、草食性鱼类生物量和水深呈显著负相关（P<0.05）；限制沉水植物生长的生态因子依次为透明度、浊度、草食性鱼类生物量和水深。水体透明度和浊度的改善、草食性鱼类的控制和水位调节是实现盐龙湖沉水植物恢复的主要方向及对策。

Succession and Driving Factors of Submerged Macrophytes in Yanlong Lake

Yanlong Lake is the drinking water source for Yancheng City, Jiangsu Province and plays an important role in ensuring urban drinking water safety. The area of submerged macrophyte (40 hm2) is the key component of the ecological purification project in Yanlong Lake, acting as an ecological barrier and improving water quality. In this study, a seasonal survey of submerged macrophyte succession in Yanlong Lake was conducted at 50 sampling sites from October 2015 to October 2019. During the same period, we completed fish surveys at three sites using gill nets of different mesh size. Based on the survey, we analyzed the status and succession rules of the submerged macrophyte community in Yanlong Lake and explored the primary driving factors for the growth and distribution of submerged macrophytes. We aimed to provide a reference for restoring submerged macrophytes and improving water quality in source water lakes. A total of 15 submerged macrophyte species were recorded in Yanlong Lake, belonging to 6families within a single phylum. The number of submerged macrophyte species by year from 2015 to 2019 was 13, 12, 9, 11 and 12. The succession of dominant submerged macrophyte species followed the order Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton malaianus, M. spicatum. Both the coverage and biomass of submerged macrophytes initially decreased and then increased, clearly degrading in 2016 and 2017 but recovering in 2018 and 2019 after ecological restoration. There was a significant positive correlation between submerged macrophyte biomass and transparency and significant negative correlations with turbidity, herbivorous fish biomass and water depth. Therefore, increasing transparency, decreasing turbidity, controlling herbivorous fish and regulating water level are the primary objectives for restoring submerged macrophytes in Yanlong Lake.