To track the impacts of environmental change and enable conservation efforts, we first must understand the composition of our ecosystems. Now, a new online resource provides a comprehensive overview of hard coral distribution across the Ryukyu Islands, based on extensive environmental DNA (eDNA) analysis.
Developed by the Marine Genomics Unit at the Okinawa Institute of Science and Technology (OIST) together with the Okinawa Environmental Science Center, the Ryukyu Islands Coral eDNA Atlas maps the distribution of reef-building corals detected from seawater samples collected at 231 different locations, including Okinawa Island, the Kerama Islands, Kume Island, and the Yaeyama Islands. Users can explore the relative abundance of different coral genera at each survey site and examine detailed information about local coral communities by selecting individual locations on an interactive map.
The website provides a comprehensive overview of reef-building coral genera detected in seawater samples collected from locations throughout the region, including Okinawa Island, the Kerama Islands, Kume Island, and the Yaeyama Islands. Users can explore the relative abundance of different corals at each survey site and examine detailed information about local coral communities by selecting individual locations on an interactive map.
Since 2021, the OIST Marine Genomics Unit has been conducting coral research using environmental DNA (eDNA), genetic material released by organisms into their surroundings. Because adult corals are sessile and remain attached to reef substrates, DNA found in seawater can provide highly accurate information about nearby coral communities. By applying a method developed by the team called Scleractinian Environmental DNA Metabarcoding (Scl-eDNA-M), which enables the simultaneous analysis of multiple groups of organisms, the researchers were able to conduct efficient, large-scale coral surveys across the region.
In addition to shallow-water data, the atlas includes survey results from mesophotic coral ecosystems at depths of 30–60 meters. Users can currently access data from 57 mesophotic sites around Okinawa Island and the Kerama Islands.
The website also features coral reef landscape photographs collected over approximately 21 years, beginning in 2004, by researchers from the Okinawa Environmental Science Center and Kaiyu Co., Ltd. These photographs were taken at a total of 193 locations, including 116 sites around Okinawa Island and nearby islands, and 77 sites around Ishigaki Island. The collection provides valuable documentation of long-term changes in coral reef ecosystems, including coral bleaching events and outbreaks of crown-of-thorns starfish.
Professor Noriyuki Satoh, who led the project, said: "With environmental DNA technology, collecting just one liter of seawater can reveal, with remarkable accuracy, which coral genera are present beneath the surface and how abundant they are. Using a database that we have built with the support of many collaborators, we created this website to help people discover and appreciate the beauty of coral reefs throughout the Ryukyu Islands. We hope the atlas will serve as a useful resource for education and research, and that it will enable future generations to learn more about the corals living in their own communities. Looking ahead, we aim to expand this initiative to cover coral ecosystems throughout Japan and eventually around the world."
The atlas is expected to support a wide range of activities, including coral reef monitoring, conservation, research, and education.
