First Report of Dryophytes japonicus Tadpoles in Saline Environment

The environment is becoming increasingly saline due to global warming and the rise of sea levels. Consequently, species living at low elevations and that are able to demonstrate tolerance to salinity are more likely to adapt to their new environment. Amphibians are especially sensitive to salinisation due to their permeable skin, which makes them osmotically sensitive. Globally, over a hundred amphibian species have demonstrated variable tolerance to salinity, but no such species has been found on the Korean peninsula. We conducted a transect survey in the intertidal zone of Sae Island, Jeju, Republic of Korea for the occurrence of Dryophytes japonicus tadpoles. We also measured salinity, distance to the water line and maximum width for each tidal pool encountered. Our results revealed the presence of D. japonicus tadpoles at all distances from the waterline, in both fresh and brackish water, and independent of the pool maximum width. Salinity and distance to the water line were not found to be of significant importance to the occurrence of the species, and calling males were present at all pools. The highest salinity measured at pools with tadpoles was 9.8 ‰, which is equal to a third of the salinity of the sea surrounding the island. This is the first such record for the species and for the Republic of Korea. Our results also highlight a potential for tolerance to salinisation of the environment in relation to climate change.