GLOBAL WARMING CAUSES CORALS TO REPLACE JAPAN’S SEAWEED BEDS

Tropical corals are increasing and seaweed beds nurturing sea creatures have disappeared in the sea south of Tokyo Bay, local divers and fishers have found, indicating that Japanese waters are not exempt from the effect of global warming, Kyodo news agency reported late on April 11, 2020.

In the waters off Kyonan in Chiba Prefecture, east of Tokyo, seaweed beds have disappeared over the past 12 years, while young table coral that usually grows in warmer waters in southwestern Japan have taken their place.

"In recent years, (the seawater temperature) hasn't fallen below 15 C even in winter," said

Jiro Uochi, a local guide and diver. Uochi, 65, said he became aware of the disappearance of the seaweed beds in the summer of 2015. And similar scenes have been seen in other parts of Japan, as tropical coral larvae carried by warm currents take over as a result of the warmer seawater temperatures, which hit a record high globally in 2019, according to the Japanese Meteorological Agency.

In Kyonan, the seawater temperature has been pushed up in the past two years due to changes in the course of the Kuroshio Current, which begins off the Philippines and flows northeastward past Japan. "With the loss of the seaweed beds, large abalone, which were our local specialty, died out," said Koichi Hirashima, head of a local fishers' association. "It's also difficult to see seasonal fish," Hirashima, 71, said, adding it has become almost impossible to catch anchovies and cherry bass, both in season in February when the sea temperature should be lower. One reason for the disappearance of the seaweed beds is believed to be that some seawaters are now warmer than 28 C. Another is the damage caused by fish such as rabbitfish, parrot fish, and sea urchins feeding on them, as they stay active during the fall and winter due to the warmer waters.