With a prolonged heat wave causing temperatures in the seas to rise, subtropical stinging jellyfish are moving closer to Korean shores and stinging beachgoers.

According to the Korea Coast Guard yesterday, a total of 575 cases of jellyfish stings on the nation’s beaches were reported over a period from July 1 to Aug. 10. On Friday and Saturday alone, the Coast Guard said more than 250 cases were reported.

“A large population of jellyfish that used to stay in the waters off the southern coast moved in last month after heavy rains and the August heat wave,” said Lee Hak-bong, an official at the Coast Guard.

Tropical jellyfish like warm waters, and the waters off Korean beaches are now warm enough to attract them.

At Hamdeok Seowubong Beach on Jeju Island, 26 swimmers reported stings by the Box Jellyfish (carybdea rastoni) Saturday, prompting the Coast Guard to clear the beach.

Gangwon’s Yangyang Beach reported 40 cases of jellyfish stings while Malipo Beach in Taean, South Chungcheong, had 72 such cases from July 1 to Wednesday.

Local governments in beach towns are scrambling to come up with ways to prevent stings.

On Aug. 10 last year, an 8-year-old girl died after she was stung by a jellyfish at Eulwangri Beach in Incheon.

Busan’s Saha and Incheon’s Jung district offices erected a 1.4-kilometer wide, 6-meter high fence-net to block the jellyfish encroachment.

Experts advise not to apply alcohol or vinegar in order to sterilize a sting because they can help the poison spread.

BY CHOI MO-RAN [jkkang2@joongang.co.k