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Waters off Jeju Seeing Change in Marine Ecosystem

Posted December. 14, 2009 09:30,   


On Tuesday afternoon, a tiny black clownfish with two white bars appeared through the mist of sea anemones 18 meters underwater near the uninhabited Seop Island off the coast of Seogwipo, Jeju Island.

It appeared to be male since its tale was light yellow. A Donga-A Ilbo reporter approached it, but the fish did not flee. Instead, it kept swimming around a colony of sea anemones.

Clownfish are native to warmer waters near Australia, where coral reefs are abundant.

Growing famous due to the 2003 animated film “Finding Nemo,” the clownfish began being discovered in waters off Jeju by underwater photographers six years ago. They are believed to have moved along ocean currents, entered the sea near the island, and settled there.

Seop and two other neighboring islands, Moon and Beom, each have an adult male clownfish. For reasons unknown, however, females are nowhere to be seen.

The water temperature was around 19 degrees Celsius, four degrees warmer than out of water. A young yellow clownfish was discovered 20 meters from the black clownfish’s habitat. Four blue clownfish were swimming beside it. Through a group of half-lined cardinal fish, a blue cardinal fish was seen.

These fish species began inhabiting waters off Jeju from 10 years ago.

A scuba diver said he witnessed a 30-meter long green sea turtle, which is likely to spend winter in neighboring waters.

On the seabed, soft coral is streaming in the water. Various kinds of coral including antipathes japonica, which is called the pine tree of the sea, were found. Pink sea squirts, which began mushrooming early in the year, were still flourishing in clusters.

The landscape of waters off Jeju is becoming subtropical. Subtropical fish species such as wrasses, basses and blackfin sweepers began breeding in the early 1990s. Most of them moved north along the Kuroshio Current and the Tsushima Warm Current and settled in Jeju waters.

Kim Byeong-il, president of Pacific Diving School, said, “Ten years ago, the lowest temperature of waters off Moon Island near Seogwipo was 13 degrees Celsius. These days, temperatures never drop below 14 degrees,” adding, “Instead of a decline in the number of soft coral species, subtropical fish varieties unseen in the past are appearing.”

Changes in marine ecosystems inevitably bring about change in fish stocks, said Myeong Jeong-gu, a senior researcher at the Korea Ocean Research and Development Institute.

“We recently discovered undocumented species in waters off Jeju Island, but haven’t reported them to the academic world,” he said.

“Some fishes sensitive to changes in surroundings should be designated bioindicators of aquatic species to monitor rises in water temperatures and changes in marine ecosystems in waters near Jeju, Geomun Island and Dokdo,” he said.

“Proper responses to changes underwater and the development of new fish stocks are possible through such studies.”