Amidst the intense heat in various places, coral bleaching was confirmed in the sea off Ishigaki Island in Okinawa Prefecture, which is believed to be caused by rising seawater temperatures. There is the potential for even greater bleaching events to occur."
Coral bleaching has been confirmed on Yonehara Beach, a popular tourist spot on the north side of Ishigaki Island.
When NHK's diving team took a picture of shallow water with a depth of about 2 meters, many corals such as Acropora coral and Porites coral were in a pure white state.
According to a group made up of businesses that conduct nature experience tours on the island, coral bleaching has been confirmed since the end of last month on the coral reefs near the Yonehara coast. Approximately 10% of them turned white and 10% of them died.
Coral bleaching is a phenomenon in which phytoplankton, known as zooxanthellae, which live together and provide nutrients to corals, is lost due to continued high seawater temperatures, leaving only white skeletons.
If the situation continues as it is, the corals will die, the balance of the marine ecosystem will be disturbed, and there is a risk that the fishing industry and tourism will be affected.
According to the Okinawa Meteorological Observatory, the sea surface temperature around the Yaeyama region, including Ishigaki Island, averaged 30 degrees last month, 0.6 degrees above the average year.
Associate Professor Takashi Nakamura of the University of the Ryukyus, who has been investigating coral bleaching for more than 20 years, said, "For the next month, the seawater temperature is expected to remain extremely high, and there is a possibility that a large-scale coral bleaching event will occur. It's getting pretty high. I'm worried that there will be damage over a wide area."
Concerned impact on tourism
Coral bleaching has been confirmed over a wide area, raising concerns about its impact on tourism.
Kenji Ohori, who conducts nature experience tours on Ishigaki Island, confirmed that corals were bleaching on the Yonehama coast on the north side of the island late last month.
When he dived into the sea and took a picture with a camera, about 80% of the coral was bleached as far as he could investigate.
Mr. Ohori says, "Coral reefs are an important tourism resource, and they are a place for children to learn about the environment. I hope that the coral will recover."
The bleaching phenomenon has also affected a company that uses "glass boats" with partially transparent bottoms to guide tourists through Kabira Bay on Ishigaki Island.
Many of the corals in relatively shallow areas that tourists can see from the bottom of the "glass boat" are bleaching, so the usual guide method has been changed to explain the bleaching phenomenon.
A 19-year-old woman who visited from Saitama Prefecture for sightseeing said, "I'm sad that the coral has turned white. I want it to return to its original color and get well without dying."
Yuya Ohama, the captain of the ``glass boat'', said, ``Following the effects of the new coronavirus and the washing of a large amount of pumice, it feels like coral bleaching.I hope the damage will not spread further.'' .
Even in the sea around Iriomote Island and Taketomi Island
Coral bleaching has been confirmed not only around Ishigaki Island, but also around Iriomote Island and Taketomi Island.
Atsushi Nanami, senior researcher at the Japan Fisheries Research and Education Agency, who studies the ecology of corals and fish, dived into the sea around Iriomote Island and Taketomi Island earlier this month and confirmed that several corals had bleached. It means that
Also, on the 5th of this month, it was confirmed that bleaching occurred not only in shallow water but also in a water depth of about 10 meters on the east side of Iriomote Island.
Because the water temperature in this area is lower than in shallow water, no bleaching phenomenon has ever been confirmed. We need to do it,” he said.
Okinawa's corals have been in danger due to "bleaching"
Okinawa's corals have often been threatened by "bleaching".
Six years ago in 2016, seawater temperatures around Okinawa Prefecture remained 1 to 2 degrees higher than normal, and coral bleaching was confirmed over a wide area.
Of these, a survey by the Ministry of the Environment confirmed that about 70% of the coral in the country's largest coral reef "Sekisei Lagoon" off the coast of Ishigaki Island has died.
In 1998, a global scale bleaching event occurred, and in Okinawa, about 80% of the coral bleached, causing serious damage, and it is said that nearly half of the coral died.
Associate Professor Takashi Nakamura of the University of the Ryukyus, who is investigating coral bleaching, said that the bleaching phenomenon confirmed this time is similar to 2016, such as the fact that the seawater temperature continues to be high and there are few approaching typhoons. It means that there is
The Ministry of the Environment will investigate how far the coral bleaching phenomenon has spread in the waters around Ishigaki Island next month.