This footage was filmed and produced 15 February 2024.

In a groundbreaking study conducted by scientists at the Okinawa Institute of Science and Technology (OIST), in collaboration with NTT Communications, researchers have successfully identified the genera of mesophotic corals using environmental DNA (eDNA) collected by underwater drones for the first time. This innovative research, published in the journal Royal Society Open Science, marks a significant advancement in the field of coral monitoring and biodiversity assessment.

Traditionally, researchers studying corals had to rely on scuba diving and snorkeling to access these invertebrate reef builders. However, these methods present limitations, particularly when identifying corals at deeper depths. By leveraging eDNA collected by underwater drones, scientists can now conduct large-scale monitoring of corals without the need for direct observations underwater, revolutionizing the way coral surveys are conducted.

The research team analyzed mitochondrial DNA, a more abundant and higher-quality genetic material compared to nuclear DNA, to identify the types of corals present in mesophotic coral ecosystems. By studying eDNA, researchers can overcome the challenges of traditional monitoring methods, such as uncertainties about the location of stationary corals and the need for specialized diving and taxonomy skills.

Professor Noriyuki Satoh, leader of the Marine Genomics Unit at OIST, collaborated with NTT Communications to develop this cutting-edge method of using underwater drones to collect eDNA samples from deeper coral reefs. The researchers conducted extensive surveys of mesophotic corals at various depths off the coast of Kerama National Park, Japan, using underwater drones equipped with sampling capabilities.

The results of the eDNA analysis revealed the presence of different genera of stony corals at various depths and locations around the Kerama Islands. The findings indicated that the composition of stony corals varied depending on depth, with certain genera more prevalent at shallow reefs compared to mesophotic sites.

NTT Communications has developed an improved version of the drone used in the study, equipped with additional sampling capabilities and extended cable length for more efficient data collection. Prof. Satoh and his team are now collaborating with mesophotic coral specialists to further test this method at study sites near Sesoko Island, with the goal of revolutionizing coral surveys and expanding research into deeper reef ecosystems.

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