Nature's checkup: Surveying biodiversity with environmental DNA sequencing

A thousand kilometers south of Tokyo, far into the largest ocean on Earth, lies a chain of small, volcanic islands—the Ogasawara Islands. 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.