Marine ecologist Gemma Galbraith builds remotely operated vehicles and uses them to assess how coral reefs are being affected by climate change

March 30, 2025 | 08:00pm

Deep dive: How I use robots to survey coral reefs

Marine ecologist Gemma Galbraith builds remotely operated vehicles and uses them to assess how coral reefs are being affected by climate change

“Deep coral reefs occur throughout the world and generally reach depths of up to 150 metres. They host different ecological communities from the shallow coral reefs that most people think of, but are relatively understudied. An analogy would be a botanist not studying any sections of the plant below the ground; ignoring deep coral reefs means missing out on understanding a big part of the habitat.

Over the past four years, I’ve been developing cost-effective methods using remote operated vehicles (ROVs) to study deep coral reefs and how they are changing with the climate. In marine ecology, a lot of research is conducted while scuba-diving, but we’re often not permitted to dive below 30 metres. We can’t afford to restrict our work to shallow depths; we need innovative ways to do deep marine science.

In this photo, I’m piloting a camera-fitted ROV at the Diamond Islets in the Coral Sea off the coast of eastern Australia. My husband and colleague, Ben Cresswell, is holding the tether and skipper Casey Castro is steering the boat. Some of the ROV cameras film continuously, and others take time-lapse photos every 10 seconds. A full survey of a reef section takes about 40 minutes. Later in the laboratory, we watch the video footage to count fish, estimate coral cover and collect other data.