{"id":35976,"date":"2024-02-20T17:55:42","date_gmt":"2024-02-20T16:55:42","guid":{"rendered":"http:\/\/44fbc9d1-ecf3-4ee4-9ed6-a33dabab88e3"},"modified":"2024-02-20T19:35:45","modified_gmt":"2024-02-20T18:35:45","slug":"underwater-drones-shed-new-light-on-mysterious-coral-habitats-heres-what-they-found","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/rss_feed\/underwater-drones-shed-new-light-on-mysterious-coral-habitats-heres-what-they-found\/","title":{"rendered":"Underwater drones shed new light on mysterious coral habitats. Here’s what they found"},"content":{"rendered":"

Researchers in Japan are using underwater drones to learn about low-light coral habitats in tropical and subtropical waters. The scientists hope that the new technique will help them understand\u00a0\u201cthe entire spectrum of the coral reef”. <\/p>

By Melissa Hobson\n <\/p>

Published: Tuesday, 20 February 2024 at 16:55 PM<\/p>

\n\n

Researchers are using underwater drones to learn about mysterious\u00a0mesophotic coral ecosystems\u00a0(MCEs) \u2013 low-light habitats in tropical and subtropical regions made up of coral<\/a>, sponges and algae.<\/p>

Because MCEs are found between 30\u2013150 metres deep, which is beyond recreational scuba diving limits, they\u2019re very hard to study. Researchers either need to use underwater robots with hi-res cameras or experienced divers with specialist equipment and an extensive knowledge of coral identification. Finding someone with both skills isn\u2019t easy.\u00a0<\/p>

Now, Professor Noriyuki Satoh and his team at\u00a0Okinawa Institute of Science and Technology<\/a>\u00a0and\u00a0NTT Communications<\/a>\u00a0in Japan has tested a new way to study these ecosystems. They used underwater drones (mini-ROVs) to collect seawater samples and\u00a0analyse environmental DNA (eDNA) to see which types of stony coral were there.<\/p>

Underwater drones collecting seawater samples around Japan’s Zamami Islands. Credit: OIST\/NTT Communications <\/figcaption><\/figure>

eDNA is already used to study marine animals and shallow reefs.\u00a0As organisms shed scales, cells, mucus or faeces, they leave little traces of their DNA behind. Researchers can analyse water samples to identify which species are present, even if they didn\u2019t see them.\u00a0<\/p>

Unlike fish, corals don\u2019t move and they \u201cconstantly secrete mucus into sea, which provides ample eDNA,\u201d they say in the study.\u00a0<\/p>

Satoh and his team used underwater drones to collect seawater samples at 24 sites in six locations between 20 and 80 metres deep around the Zamami Islands in Japan\u2019s Okinawa Archipelago \u2013\u00a0a region with incredibly clear waters and among the highest diversity of stony corals in the world.\u00a0<\/p>

The Zamami Islands form part of the Okinawa Archipelago. Credit: Getty<\/figcaption><\/figure>

When they filtered and analysed the samples, they found the reef composition varied at different depths.\u00a0Acropora<\/em>corals (the family which includes table, staghorn and elkhorn coral) were more common in shallower reefs while they found a higher proportion of\u00a0Porites<\/em>\u00a0at the MCEs.<\/p>

They are still working to perfect the process and minimise cross-contamination of samples but their initial findings suggest this method is viable for sampling MCEs.<\/p>

\"Underwater
Map showing the seawater sampling sites at 6 monitoring locations around Zamami Island. Credit: Okinawa Institute of Science and Technology Graduate University (OIST)<\/figcaption><\/figure>

Satoh hopes this new technique will help researchers conduct broader monitoring to improve their knowledge of\u00a0\u201cthe entire spectrum of the coral reef, from the shallow waters to the mesophotic zones, and even the sandy depths,” he\u00a0told\u00a0Science Daily<\/em>.\u00a0<\/p>

Although we have much to learn about MCEs, we already know how important it is to learn more about them. These reefs are home to a higher proportion of endemic species than shallow water corals so play a vital part in keeping the ocean healthy.\u00a0<\/p>

Scientists analyse underwater drone footage. Credit: OIST\/NTT Communications<\/figcaption><\/figure>