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This underwater drone hunts and kills invasive starfish on the Great Barrier Reef

Crown-of-thorns starfish are literally devouring Australia’s Great Barrier Reef, an overpopulation problem that is threatening the coral that forms the reef. To save it, researchers have developed an underwater vehicle capable of destroying the hungry starfish quickly and efficiently.

The COTSbot underwater drone, developed by Matthew Dunbabin and Feras Dayoub of the Queensland University of Technology, is equipped with stereoscopic cameras for depth perception, pitch and roll sensors for movement control, and GPS to aid in its navigation. The COTSbot is equipped with a sophisticated, crown-of-thorns starfish (COTS) detection system that, with training, can recognize a such creatures without human intervention.

COTSbotThe software was developed using imagery provided by divers who are manually eradicating the starfish; it provides the robot with the ability to learn from its experiences in the field. “Human divers are doing an incredible job of eradicating this starfish from targeted sites but there just aren’t enough divers to cover all the COTS hotspots across the Great Barrier Reef,” Dunbabin said.

If the robot is unsure of its target, it can send a picture to a person for evaluation and verification. Following confirmation, the robot can use the imagery for future COTS detection. When the COTSbot identifies its target, it delivers a lethal dose of bile salt into the starfish via a pneumatic injection arm. The system can detect and kill up to 200 starfish in an eight-hour trek. After the drone has made its sweep, divers then can enter the water to remove any remaining starfish.

Dunbabin built the detection system over a decade ago, but said he shelved the project because there were no efficient means of killing the hardy crown-of-thorns starfish in situ. At that time, divers were required to inject each starfish up to 20 times, a process that would not be compatible with the underwater drone. A breakthrough by researchers at James Cook University (JCU) was a game changer for Dunbabin, allowing him to equip his underwater vehicle with a system that would kill the starfish with a single injection.

“I was really pleased to hear about JCU’s announcement last year of a one-shot injection method that had proved just as effective,” he said.

The COTSbot recently passed a field trial in Moreton Bay in Queensland, Australia, and is headed to the Great Barrier Reef where it will begin trials with live crown-of-thorns starfish. In this first trial, a human will verify each COTS before injection. Researchers hope to run the robot autonomously starting in December.

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