基于水下光照条件和种子库分布指示沉水植物恢复区:以金湖为例

INTEGRATING UNDERWATER LIGHT CONDITION AND SEED BANK TO INDICATE SUBMERSED MACROPHYTE RESTORATION ZONE:LAKE JINHU AS A CASE

研究以湖北枝江金湖(由东湖和刘家湖组成)为例,综合水下光照条件和沉水植物种子库分析,探讨沉水植物可恢复区的判别方法。研究分别于2018年6月和12月对金湖开展了综合调查,并在6月开展了种子库调查。结果表明,金湖富营养化问题较严重, 6月各位点水深-透明度比值均低于沉水植物生长的阈值需求,范围为0.13—0.25,平均为0.17;12月部分位点的水深-透明度比值达到了沉水植物生长的阈值需求,范围为0.18—0.95,平均为0.44。各位点沉水植物种子库密度范围为0—200 ind./m^2,平均为24 ind./m^2。根据金湖的水下光照条件和沉水植物种子库分布情况,结合湖底地形,建议在冬春季透明度较高的时期降低水位,进行沉水植物恢复工作。通过水下地形、光照条件和种子库的综合分析,对金湖的沉水植物恢复区进行了划分,结果显示东湖的东南部、东湖的西岸、刘家湖的西部和东岸作为沉水植物恢复区较为合适。该研究有望为湖泊沉水植物的恢复提供定量化的参考建议,提高生态修复工程效果和降低管理成本。

Submersed macrophytes play an important role in maintaining lake ecosystem health and supporting fishery sustainability.The restoration of submersed macrophytes is an effective measure of ecological reconstruction in shallow lakes.However,assessment of the restorable zone of macrophytes is usually neglected in practical ecological restoration,resulting in low survival rates of introduced submersed macrophytes.In this study,Lake Jinhu(with two subareas,Donghu and Liujiahu),Zhijiang,Hubei Province,was studied as a case with the purpose of developing a method to assess the restoration zone of submersed macrophytes by integrating the underwater light climate and seed bank of submersed macrophytes.Two comprehensive surveys were carried out in June and December 2018.The seed bank of submersed macrophytes was analyzed in June.The ratio of Secchi depth to water depth and the seed bank distribution of submersed macrophytes were selected as the key factors to assess the restoration zones.The results suggested a serious eutrophication of Lake Jinhu.In June,the ratio of Secchi depth to water depth ranged from 0.13 to 0.25,with an average of 0.17,all much lower than the required thresholds for the regrowth of submersed macrophytes.In December,the ratio of Secchi depth to water depth ranged from 0.18 to 0.95,with an average of 0.44,mostly meeting the requirement for macrophyte growth.The density of the submersed macrophyte seeds ranged from 0 to 200 ind./m2,with an average of 24 ind./m2.Based on the underwater light climate and the spatial distribution of the seed bank,combined with the topography of the lake bottom,we suggest that the water level be lowered in winter and spring.The southeastern part of Lake Donghu,the western bank of Lake Donghu,and the eastern bank and the western part of Lake Liujiahu are zones suitable for the restoration of submersed macrophytes.The relevant findings are expected to benefit lake management in restoring submersed macrophytes by improving the efficiency of ecological restoration while lowering the cost of management.