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Scientists and divers concerned about'slumping' corals in South Korea

Ko Myeong -hyo was captivated by the vivid colours and vibrant life of South 'Korea soft corals six years ago when she began diving near the coast of Jeju Island to harvest fish for sale.

It was disorienting to watch the coral garden collapse and turn white. This is after two years of higher temperatures and more harsh weather caused by climate change.

I was worried that the entire sea could collapse.

This year the "slumping phenomenon" is again visible, according to the Paran Ocean Citizen Science Center. The center is a group that monitors the soft corals on the island, which are listed by UNESCO. They do this mainly around the uninhabited islets located south of Jeju.

The group claims that roughly half of a cluster near the island of Beomseom is struggling.

Soft corals are dependent on fluid pressure within to maintain their upright position. Changes in the environment can cause this pressure to be disrupted, causing them to collapse or sag.

Researchers Kim Taihun and Kim Yu-seong said that corals can recover partially if another large'slumping" occurs, but then some will break off, and the rest will deteriorate. This cycle keeps repeating itself, and their ability to recover keeps decreasing.

Kim and Anna Beate Jost (a colleague from the Korea Institute of Ocean -Science and Technology, KIOST) documented Jeju’s soft coral collapse event in 2024 for the first in a journal article published in May.

Korea Heritage Service (which manages the soft-coral colonies designated as a national landmark) said in an email that it had monitored the situation over the past year and would continue to do long-term research on the causes of the changes.

The Oceans Ministry which is responsible for marine protected species, such as soft corals and other areas, has announced that it will conduct a detailed investigation in order to determine the extent of damage.

EL NINO MAY WORSEN THE EVENT THIS YEAR

Kim said that this year's event was similar to the one of 2024. However, it could get worse if high water temperatures continue through September and if El Nino weather phenomena triggers typhoons or heavy rains.

He called for a quantitative and consistent monitoring of the loss in soft corals due to slumping.

Corals have been affected by climate change around the world, but the Great Barrier Reef in Australia has received the most attention.

This year, a record heatwave has drenched the Korean Peninsula while heavy rains have lashed the South.

Researchers say that such weather conditions and water flowing from China's Yangtze River, which affects the salinity of the area, could trigger "slumping".

Jeju’s waters provide a safe haven for soft coral communities that are sensitive to environmental conditions, and live on the border of acceptable conditions at the northernmost limit in coral distribution of the East China Sea.

Soft corals are the nursery for Jeju's marine eco-system, and they live in Jeju Island Biosphere Reserve (a UNESCO listed reserve).

Yoon Sanghoon is an environmental expert from Paran. He said that the seaweed and coral seas are the foundational ecosystem of Jeju's marine eco-system.

If this base ecosystem collapses there is a possibility that the entire marine eco-system could?collapse.

Weather authorities report that marine heatwaves in Korea have lasted almost four times as long, or 83.3 days.

RIPPING IMPACT

Paran was formed in 2023, by Jeju residents who were 'concerned about marine changes.' It brings together office workers, traditional divers, and documentary filmmakers, all of whom flock to the island for monthly dives.

Scientists can use the photos and documents they take to document any changes.

Ko, who is a Jeju third-generation "haenyeo", or "seawoman", can dive as deep as 8 m (26 feet) using only her breath. However, when diving deeper into coral reefs, she uses an oxygen tank.

Son Choon Sook, 70, a mother of a diver who started diving 45 years earlier, says that the warming waters have changed the seabed.

She said, "I worked on the sea for 45 years and earned money. I also sent my children to school with it." "Now that the catch has dried up, it makes me sad."

She said that the smaller catch in the past few years is due to summers where the water was too warm for the species to reproduce. Her workday, which used to be five hours, has been reduced to three, partly because there are fewer fish to collect, but also to improve her health.

Ko says that her recent summer dives have caused her to worry again. She added, "Rather than seeing beautiful coral shapes I feel as though I am now seeing more sick coral."

(source: Reuters)