There’s trouble brewing in the Great Barrier Reef off the coast of northeastern Australia. An underwater pest known as the crown-of-thorns starfish (COTS) is causing a huge amount of damage, estimated to be responsible for 40% of the reef’s decline in coral cover.

So, to combat it, scientists from the Queensland University of Technology (QUT) are preparing to deploy an autonomous robot known as the COTSbot. This small submersible, armed with cameras, five thrusters and GPS, can seek out and kill COTS, using a pneumatic arm to deliver a lethal injection.

What makes this possible is a piece of COTS-detecting software that has been in development for six months using thousands of images and videos of the reef. This allows the robot to identify and destroy COTS among other underwater wildlife. Although the robot operates by itself in the water, it will take an image of an object to be examined later by a human if it is unsure a target is a COTS.

The injection itself, developed by James Cook University (JCU) in Queensland, can kill a COTS with just one shot. Human divers can then come in and finish off any survivors.

At first, just one submersible is being used. It can search for eight hours, and deliver 200 lethal shots in that time. But ultimately, the scientists envisage a team of 10 to 100 scouring the coral reef, working day and night and in all weather.

^{Dr. Matthew Dunbabin (front) and Dr. Feras Dayoub are seen lowering the COTSbot into the water. Kate Haggman/Flickr.}

"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," Dr. Matthew Dunbabin, from QUT’s Institute for Future Environments, said in a statement.

"We see the COTSbot as a first responder for ongoing eradication programs – deployed to eliminate the bulk of COTS in any area, with divers following a few days later to hit the remaining COTS."

The robot completed its first sea trials this week in Queensland’s Moreton Bay, testing its mechanical parts and navigation system. It will begin active trials in the Great Barrier Reef later this month, with a human helping to identify each COTS at first. Ultimately, the team hope for it to be working autonomously by December.