Abstract: In order to understand the habitat selection and spatial distribution of red swamp crayfish (Procambarus clarkia) and its influence on native amphibian diversity, an investigation was made in 86 reservoirs and ponds on eight islands (Daishan, Liuheng, Xiushan, Fodu, Taohua, Xiazhi, Cezi, and Putuo Mountain) of Zhoushan Archipelago in May–August 2008 by the methods of transect line, visual encounter survey, and net catching. Based on the investigation, the distribution and density of the crayfish in the water bodies were studied, with the related affecting factors analyzed. The results showed that 83.7% (72/86) of the water bodies had the distribution of P. clarkia, and 53.5% of them had the co-occurrence of P. clarkia and American bullfrog Rana catesbeiana. The density of P. clarkia in its invaded water bodies differed  the islands. The minimum adequate model based on information criterion (AIC_c) displayed that the occurrence of P. clarkia was positively correlated  maximum water depth and R. catesbeiana density. It was suggested that the occurrence of the crayfish might have little direct effects on the native frog species richness in permanent lentic water bodies. As an important ingredient of bullfrog diet, the crayfish’s distribution could potentially promote the density of bullfrog co-occurred with the crayfish.

Key words: Forest health, Risk assessment, Forest resource management