Kuroshio Current

Nature has been able to develop on its own terms here, far from both humans and the warm Kuroshio current, which acts like a shuttle, moving marine species from Taiwan, over the Ryukyu Islands, and up the Pacific coast of mainland Japan.

"Photosynthetic acoels are mostly found in warmer waters. Therefore, we focused our sampling in Southern Japan. We also found acoels near Kochi, a region of Japan that receives warm water from the Kuroshio Current. Photosynthetic acoels can be difficult to spot -- they are microscopic. But, under a microscope they are easily recognizable, by their brightly colored algae," Siratee continued.

The dispersal pathway of the Kuroshio Current indicates that Borelis matsudai likely appeared in the southern and central Ryukyu Islands at least since the Middle Pleistocene, around 770,000 years ago.

Consequently, the Sekisei Lagoon marks a significant biogeographical milestone in the northward migration of benthic organisms within coral reefs along the Kuroshio Current's dispersal route.

Experts say the waste water could be carried by ocean currents, particularly the cross-Pacific Kuroshio current.