Occurrence and disappearance of a non-native goby Rhinogobius sp. OR in relation to hydrological conditions in the Kamo River, southwestern Japan

We monitored the abundance of a non-native ( Rhinogobius sp. OR) and two native stream gobies ( R. fluviatilis and R. nagoyae ) over a decade, from 1995 to 2004, in a fixed reach of a tributary of the Kamo River, southwestern Japan. The non-native Rhinogobius sp. OR appeared and reproduced in 1997, when an increased deposition of fine sediments occurred. However, after a severe spate in 1999, the non-native goby almost completely disappeared from the study reach, while the density of the native R. fluviatilis increased. The severe spate is likely to have prevented the establishment of the non-native goby. Our results provide an example of abiotic barriers to invasion.