Abstract

Small streams and connected estuaries on Jeju Island off the south coast of Korea are unique habitats for some marine invertebrate animals, including the neritid gastropod Clithon retropictum (v. Martens, 1870). According to the Korean wildlife protection and management act, the estuarine gastropod C. retropictum is one of the level II endangered animals due to its vulnerable habitat. In this study, we report three small streams connected to the sea on Jeju Island, Woldaecheon stream on the north, Changgocheon on the south, and Hadori migratory bird habitat on the east coast as new habitats of C. retropictum. Egg capsules of C. retropictum were commonly observed in the newly found habitats, although the density in each habitat was low, with less than one individual per m2. Along with the previously reported habitats of C. retropictum on Jeju Island, those new habitats require special attention to protect from anthropogenic activities which may deteriorate and destroy the habitat.