外来鱼类革胡子鲶与本地鲶的功能反应及生物学特性的比较

Comparison of functional responses and biological characteristics between exotic species Clarias gariepinus and native species Silurus asotus

珠江水系是中国遭受外来水生动物入侵最严重的水域之一,分布有许多种外来鱼类,然而这些外来鱼类对本地鱼类资源的影响尚缺乏有效的评估。比较功能反应被认为是量化外来物种生态影响的有效方法之一。本研究采用控制实验对外来鱼类革胡子鲶(Clarias gariepinus)和本地鲶(Silurus asotus)的功能反应进行了比较。实验以鲮(Cirrhinus molitorella)、广东鲂(Megalobrama hoffmanni)和草鱼(Ctenopharyngodon idellus)的幼鱼为饵料,按照1、2、4、8、16和32条的饵料密度进行投喂,设置3个重复组,研究了革胡子鲶和鲶的功能反应类型,建立了功能反应的曲线,并拟合了功能反应的参数;同时分析了革胡子鲶和鲶的食物转化效率并比较了二者的生物学特性。结果表明:革胡子鲶和鲶的功能反应类型均为Type II型。与鲶相比,革胡子鲶具有更高的单位资源消耗率即更强的袭击率(P<0.05),而两种鱼对猎物的处理时间则无显著区别(P=0.272);革胡子鲶的食物转化效率显著低于鲶(P<0.05),为鲶的0.57倍,两种鱼的相对生长率则无显著差异(P=0.762)。本研究为系统评估革胡子鲶的生态影响提供基础,同时为量化其他外来鱼类的资源消耗率及潜在的生态影响提供借鉴。

The Pearl River system is one of the rivers being most severely invaded by exotic aquatic animals in China.While the invasive species are diverse,the impacts of exotic fish on local fish resources has not been effectively evaluated.Comparative functional response is considered as an effective approach to quantify the potential ecological impacts of exotic species.In this study,adopting a manipulated experiment,we compared the functional responses of an exotic species,Clarias gariepinus and a native species,Silurus asotus.Cirrhinus molitorella,Megalobrama hoffmanni and Ctenopharyngodon idellus were used as feeding materials with bait density of1,2,4,8,16,and 32,and three replicates for each treatment.We analyzed the types of functional responses,constructed the curve of functional response and fitted the parameters of the functional response.In addition,food conversion efficiency and biological characteristics of C.gariepinus and S.asotus were compared.The results showed that both C.gariepinus and S.asotus exhibited Type II functional response.Compared with S.asotus,C.gariepinus had a higher rate of unit resource consumption,i.e.,a stronger attack rate(P<0.05),while there was no significant difference in the handling time between the two species(P=0.272).Food conversion efficiency of C.gariepinus was significantly lower than that of S.asotus(P<0.05).There was no significant difference in the relative growth rate between both species(P=0.762).Our results provide a basis for future systematic assessment of the ecological impact of C.gariepinus and can serve as a reference for quantifying resource consumption rate and potential ecological impacts of other exotic fishes.