As cities expand, Korea’s threatened salamanders feel the squeeze

It’s no secret that as cities expand into the wild, the animals, plants and fungi that live there are often pushed from their homes or worse, with possibly devastating effects on the ecosystem and even the planet. On the Korean peninsula, where new development is expanding rapidly, the effects of urbanization have been especially devastating for Korean salamanders, a group that has become more threatened over the last 20 years, according to the second global amphibian assessment —a mammoth undertaking that took nearly a decade to complete. 

The second Global Amphibian Assessment offers a glimpse at how the planet’s frogs, toads, axolotls, newts, caecilians and salamanders are faring in the anthropocene. The order Caudata, which contains the planet’s approximately 800 species of salamanders, is in an especially precarious position. 

Continental northeastern Asia is home to 16 salamander species, 11 of which live on the Korean peninsula. All salamander species on the Korean peninsula are more threatened since the first global amphibian assessment was published in 2004. The concerning trend is being driven by several factors, but the leading cause, especially for newly described species, is urbanization. 

Several salamander species on the Korean peninsula have only been officially described by science during the past decade: Yangsan Clawed Salamander (Onychodactylus sillanus), Cryptic Uiryeong Salamander (Hynobius perplicatus), Southern Korean Salamander (Hynobius notialis), Korean Small Salamander (Hynobius unisacculus) and Geoje Salamander (Hynobius geojeensis). Although scientists have only recently confirmed that they are distinct species, the salamanders have faced the same threats over the last two decades. 

“For most of them, we found that urbanization is a threat because it impacts some core areas of the range, especially for the latest described species,” says Amaël Borzée, professor at Nanjing Forestry University, co-chair of the IUCN Amphibian Specialist Group (ASG) and one of the co-authors of the second global amphibian assessment, which was coordinated by the Amphibian Red List Authority, a branch of the ASG, hosted and managed by Re:wild.

The Yangsan Clawed Salamander (Onychodactylus sillanus) is a new salamander species Borzée and his colleagues described in 2022. It has a reddish-orange belly with a dark brown back and yellow spots. Although it was only recently described by science, the colorful species could be pushed to extinction because its habitat is being destroyed.

“We found that because the range of the species is between three expanding metropolitan areas that are on the verge of connecting, urbanization and city-expansion into the natural landscape is a very potent threat to that species,” says Borzée.  

The Yangsan Clawed Salamander is only found in a small area in the mountains at the southern tip of the Korean peninsula. The lungless salamander breathes through its skin and depends on pristine streams that are “totally untouched.”

“They cannot accept habitat change,” says Borzée. “They have very specific ecological requirements. Manmade or substitute habitats just do not work [for them].”

Salamanders in the Onychodactylus genus breed in subterranean caves. Researchers have only identified one regular breeding site in all of continental northeast Asia for the genus, which includes the Yangsan Clawed Salamander. The only effective way to protect them is to protect their habitat. Any changes in the water quality or water levels could push the Yangsan Clawed Salamander to extinction.

The Yangsan Clawed Salamander is getting some help from local NGOs and the government of South Korea. They are working together to create protected areas for the salamanders.

“Streams are often the first habitats to be impacted by urbanization and stream-breeding salamanders, such as those native to South Korea, are especially vulnerable to these disturbances because of their sensitivity to changes in water quality,” says Kelsey Neam, species priorities and metrics coordinator for Re:wild and one of the lead authors of the second global amphibian assessment. “Unlike other forms of land-use change, urbanization is almost always a permanent transformation of the landscape, which means in order to save these species we must protect any remaining habitat and restore habitat where we can.”

Since 2012, satellite images have captured a dramatic change in forests of the Democratic People’s Republic (DPR) of Korea. It was once a bare spot on images, but now is reforested. The images suggest that across the demilitarized zone on the Korean peninsula, there could potentially be habitat in DPR Korea that could help salamanders if climate change forces them to shift north–but only if those habitats are connected with habitat in the Republic of Korea. 

“Habitat restoration in DPR Korea is most likely one of the key factors for the survival of salamanders facing climate change,” says Borzée. “Suitable habitat is found further north, but displacement to reach this habitat is impossible if the habitat is not connected.”

The Yangsan Clawed Salamander isn’t the only species losing habitat to humans. The Geoje Salamander (Hynobius geojeensis) was described by science in 2021 and is the most threatened salamander species on the Korean peninsula. It’s only found on a small island —Geoje.

“It’s one of the most rapidly developing areas in South Korea because some of the largest naval shipyards in Asia are attached to this island,” says Borzée. “In addition, there are projects to build golf courses in the area used by the species, which is already impacted by the very quickly expanding cities.”

Herpetologists and conservationists are also beginning to see the effects of climate change on the Korean Salamander (Hynobius leechii), the most abundant salamander species on the peninsula and in northeastern continental Asia. Korean Salamanders —as well as several other species in the Hynobius genus— have coped with urbanization fairly well and can still be found even in busy places like city parks as long as they have clean water. Climate change, however, is affecting their behavior and reproduction.

“For Hynobius we find them breeding earlier and earlier in the year,” says Borzée. “We found there’s a clear shift in breeding phenology, they breed earlier.”

Researchers are not sure yet how earlier breeding seasons are affecting salamanders in the genus Hynobius and their offspring, but they are worried that an earlier breeding season puts them at a disadvantage. It’s possible the tadpoles could be out of sync with other species in their environment. The tadpoles may not have enough food when they hatch if insects that they normally prey on have not shifted their breeding seasons similarly. 

Borzée thinks that the new Global Amphibian Assessment, which found that climate change is emerging as a major driver of amphibian declines globally, underscores the need for more data.

“We cannot have a clear understanding of the impact of climate change for all of the species, which is sad because climate change is having a much stronger impact than we think,” says Borzée.

Herpetologists are racing to describe salamander species in northeast Asia before it’s too late because species that are understudied and not named receive less conservation attention. Researchers predict that salamanders could experience a huge decline in the next three generations— up to 97%. Even abundant salamander species that are known, named and studied could disappear, which could have dire consequences for the ecosystem. 

“If a Hynobius species goes extinct, then there will be a lot of missing links in the carbon sequestration chain and soil aeration,” says Borzée. “Salamanders are clearly a strong link in all ecosystem services.”