A thousand kilometers south of Tokyo, in the largest ocean on Earth, lies a chain of small, volcanic islands — the Ogaswara Islands. Nature has been able to thrive here on its own terms, far from both humans and the warm Curio Current, which acts like a shuttle, transporting marine species from Taiwan, to the Ryukyu Islands, and to the Pacific coast of mainland Japan. Is. With more than 70% of the trees and many animal species endemic to the archipelago, the islands have been dubbed the ‘Galapagos of the East’, valued as both a biodiversity hotspot and a cradle of scientific discovery. are For this reason, they were designated a UNESCO Natural World Heritage Site in 2011.

Although nature here is largely unspoiled by direct human intervention, it faces global threats to biodiversity from climate change. Geographic isolation is both a blessing and a curse, as it is difficult to regularly assess the ecological health of these unique islands. However, advances in environmental DNA (eDNA) sequencing may make it safer, cheaper, and less prone to human error to monitor the state of natural affairs here and in other remote areas.

In 2021, an expedition of researchers from the Okinawa Institute of Science and Technology (OIST) visited the islands, and on board were PhD student Ayşe Haruka Oshima Açıkbaş and Professor Timothy Ravasi of the Marine Climate Change Unit at OIST. . Professor James Reimer from Ryukyus University. The trio joined a campaign at OIST to collect buckets of seawater at specific points around the island for the lab, to calculate the fish and coral populations on the islands. Their findings, analyzed together with colleagues from the Marine Genomics Unit at OIST, have now been published in the journal Environmental DNA.

The researchers took samples from the waters around two of the 31 Ogasawara Islands, and from those alone, the researchers detected 124 unique species of fish and 38 unique species of coral. To their surprise, they discovered species that had not been previously recorded or thought to have no range in the region, including fish and coral species that are beyond their expected limits. One of these beauty corals (Catalaphyllia jardinei) is vulnerable to overexploitation due to its attractiveness to aquarium enthusiasts, its ease of harvesting and maintenance. “Islands are potentially an important source of fish and coral larvae, like Catalaphyllia, for biodiversity in the wider Pacific region,” explained Ayşe Haruka Oshima Açıkbaş, first author of the study.

The study also shows the impact of human development on biodiversity. The team sampled seawater from three locations located relatively close to Futami Bay on Chichi Island, where the main settlement harbor is located. “On the western and eastern sides of the bay, we found a lot of coral species richness. But inside the small harbor we found very little richness — so even locally like that, we’d see an impact on coral biodiversity. are what human development has done.”

While its geographic isolation and low level of development may appear to make the Ogasawara Islands a safe haven for biodiversity, they are ultimately not immune to global and local threats. There have been reports of coral bleaching and destruction of local coral reefs over the years as a result of port construction. “This is cause for concern, and points to the importance of biomonitoring efforts with techniques such as eDNA sampling,” says Professor Ravassi.

The high level of extremism here is a source of both scientific inspiration and concern, as it is on the Galapagos Islands. As Ayşe Haruka Oshima Açıkbaş warns, “If you lose a native species here, they become extinct — and you lose a very important component of the ecosystem that makes it an ecosystem. Is.”

Taking seawater samples for eDNA analysis can offer an efficient means of monitoring biodiversity in remote locations such as the Ogasawara Islands, compared to traditional methods involving expert divers or camera drones. This approach not only complements routine data collection, but also has the potential to involve citizen scientists and government workers such as park rangers, enabling easier and more comprehensive monitoring of ecosystem health. As Professor Ravasi notes, “Technology has improved over time, making the cost of deployment cheaper, leading to greater adoption, resulting in increased innovation and cost savings. There’s a decline. It’s a positive spiral.” Ayşe Haruka Oshima Açıkbaş joins in: “Although our sampling was a single event, the results from the research can be used for future references. More broadly, for eDNA analysis. Water sampling can be easily integrated into ongoing biomonitoring efforts.”