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[Newsletter No.38] 12 Frog Species Confirmed on 156 Islands in Korea
CBD-CHM Newsletter Vol. 38
12 Frog Species Confirmed on 156 Islands in Korea
The Honam National Institute of Biological Resources (HNIBR), under the Ministry of Climate, Energy and Environment (MCEE), announced that research on amphibians1) conducted across 263 islands in Korea over the past 5 years confirmed the presence of 12 frog species on 156 islands, representing about 60% of the islands surveyed.
Frogs are highly sensitive to changes in temperature and environmental conditions, making them important indicator species2) of ecological change. Their body temperature varies with the surrounding environment, and they typically emerge from hibernation around Gyeongchip, one of the 24 seasonal divisions, which falls on March 5.
Although a total of 17 frog species3) are known to inhabit Korea, systematic surveys of frog populations on islands have been limited. In response, the HNIBR initiated this study to better understand amphibian distribution in island ecosystems.
The research team conducted a comprehensive analysis of 263 islands, including Jeju Island and Baengnyeongdo Island, by integrating existing literature with field surveys. The study covered a wide range of islands in the West and South Seas, from small islands such as Gaudo Island (0.32 ㎢) to larger ones such as Jeju Island (1,846 ㎢).
The results confirmed the presence of 12 frog species on 156 islands, including Jeju Island, Baengnyeongdo Island, Ulleungdo Island, and Geojedo Island. Notably, 32 islands, including Sonjukdo and Yuldo Islands, were identified as new habitats where frog populations had not previously been recorded.
The 12 frog species identified on the islands include Rana huanrenensis, Pelophylax chosenicus, Bufo gargarizans, Kaloula borealis, Bombina orientalis, Dryophytes suweonensis, Glandirana rugosa, Pelophylax nigromaculatus, Dryophytes japonica, Rana uenoi, Rana coreana, and Lithobates catesbeianus.
Among these, the most widely distributed species was Dryophytes japonica, recorded on 143 islands, including Aphaedo and Sinjido Islands. This was followed by Pelophylax nigromaculatus, found on 113 islands, including Dolsando and Changseondo Islands.
Endangered wildlife species were also identified, including Dryophytes suweonensis, classified as Class I endangered wildlife, and Class II species such as Kaloula borealis and Pelophylax chosenicus. These species were mainly found on islands along the central and northern west coast, as well as parts of the southern coast. Notably, Dryophytes suweonensis was recorded on only a single island in Ganghwa County, indicating the most limited distribution.
For the protection of endangered species, specific island names are not disclosed.
The research team also performed genetic analyses of two species, Dryophytes japonica and Bombina orientalis, to examine differences between island and mainland populations.
The results revealed distinct genetic variations in some island populations, including those on Geojedo Island, suggesting that geographic isolation may have led to the development of unique genetic characteristics.
The researchers suggest that the occurrence of frogs on islands in the West and South Seas can be explained by historical land connections during the Ice Age, when many of these islands were part of the Korean Peninsula. Rising sea levels later isolated these populations, shaping their current distribution. In contrast, the presence of Pelophylax nigromaculatus on Ulleungdo Island in the East Sea is believed to result from human-mediated introduction.
A senior researcher at HNIBR stated, "This study provides a scientific analysis of the distribution patterns and diversity of frog species across Korea's islands. The genetic findings indicate that some island populations exhibit characteristics distinct from mainland populations, highlighting the conservation value of island ecosystems from a genetic perspective.
1)
Vertebrates that live both in water and on land, including frogs, toads, and salamanders
2)
Species that indicates environmental conditions in a given area, such as climate and water quality
3)
17 spescies listed ins the National Species List of Korea: Rana huanrenensis, Pelophylax chosenicus, Dryophytes flaviventris, Bufo gargarizans, Kaloula borealis, Bombina orientalis, Bufo stejnegeri, Rana dybowskii, Dryophytes suweonensis, Rana amurensis, Glandirana rugosa, Bufo raddei, Pelophylax nigromaculatus, Dryophytes japonica, Rana uenoi, Rana coreana, and Lithobates catesbeianus
