Gushicha Gusuku, on Kume-jima Island, Okinawa Prefecture, central Ryukyu Islands, southern Japan, Pacific Ocean (26°22'52.6"N, 126°45'15.2"E; 26.3814°, 126.7542°); sandy bottom with pebbles in a small creek originating from a freshwater spring within the upper intertidal zone of the uplifted coral reef, surrounded by salt-marsh vegetation