Abstract: 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 of 1, 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.

Key words: Jianfengling tropical montane rain forest., species abundance weighted, functional diversity, functional traits, forest canopy