长江口中华绒螯蟹幼蟹对人工漂浮湿地生境的选择利用

Selection and use of artificial floating wetland habitats for larval Chinese mitten crab in the Yangtze Estuary

栖息地生态修复是养护渔业资源、实现可持续产出的重要手段。针对长江口中华绒螯蟹(Eriocheir sinensis)幼蟹栖息地生境退化甚至丧失的现状,本研究在长江口水域构建人工漂浮湿地生境的基础上,通过连续调查中华绒螯蟹幼蟹的栖息密度、规格组成及其生长特征,研究中华绒螯蟹幼蟹对人工漂浮湿地生境的选择利用状况,为长江口中华绒螯蟹幼蟹栖息地的生态修复提供参考。结果表明,人工漂浮湿地构建可以形成芦苇群落和多种生物栖息共生的立体人工漂浮湿地生境。6—10月,中华绒螯蟹幼蟹均可选择人工漂浮湿地生境作为栖息地,最高栖息密度可达466.6 ind/m^2,随着时间延长,栖息密度显著降低(P<0.05)。人工漂浮湿地生境上,不同规格中华绒螯蟹幼蟹组成存在着月份间变化,6月和7月以体重小于0.2 g的小个体为主,分别占总数量的98.1%和66.0%;8月以0.2~1.0 g个体为主,占总数量的84.7%;9月以1.4~1.8g个体为主,占总数量的74.0%。中华绒螯蟹幼蟹的头胸甲长(CL)与体重(W)的关系式为W=0.5323CL^2.3673(R^2=0.9669),幂指数(b=2.3673)小于3,显示中华绒螯蟹幼蟹的头胸甲长生长优于体重生长。人工漂浮湿地生境为中华绒螯蟹幼蟹的生长发育提供了替代生境,可满足其早期发育阶段对隐匿和摄食等生境条件的需求。

Habitat restoration is a crucial measure for conserving fishery resources and maintaining sustainable production.The habitat of juvenile Eriocheir sinensis in the Yangtze Estuary has been seriously degraded.In this study,the density,size composition,and growth characteristics of juvenile E.sinensis in artificial floating wetland(AFW)habitats were continuously monitored from May to November.The objective was to assess if juvenile E.sinensis select and use the AFW habitats,which will provide important information for future habitat restoration efforts in the Yangtze Estuary.The results show that the three-dimensional AFW habitats supported Phragmites australis and a variety of aquatic organisms that lived symbiotically.Juvenile E.sinensis inhabited in the AFW habitat from June to October,and the highest density was 466.6 ind/m^2.However,the density decreased significantly with time(P<0.05).There were differences in the size composition of larvae across months.Larvae with body weight<0.2 g were abundant in June and July,accounting for 98.1%and 66.0%of the total,respectively.Larvae weighing 0.2 g to 1.0 g were abundant in August,accounting for 84.7%.Larvae weighing 1.4 g to 1.8 g were abundant in September,accounting for 74.0%.The exponential value(b)of the carapace length-weight relationship(W=0.5323×CL^2.3673;R^2=0.9669)was 2.3673,indicating isometric growth(i.e.,carapace length growing faster than body weight).The AFW provides an alternative habitat for juvenile E.sinensis,which meets the habitat requirements of hiding and feeding in the early development stages.