A stealthy autonomous underwater robot that may track elusive underwater creatures without disturbing them may help us better understand the most significant daily migration of life on the planet.
Mesobot, a 250-kilogram robot that operates either unconnected to a power source or tethered with a lightweight fibre-optic cable, has the ability to move around below the top unobtrusively.
The ocean’s twilight zone – known more formally as the mesopelagic zone – lies between about 200 metres and 1 kilometre comprehensive. It’s the site of the diel vertical migration (DVM), a daily phenomenon where deep-dwelling animals come nearer to the surface to prey on the more plentiful food supplies found there, while dodging predators.
The DVM sometimes appears by biologists as an essential manner in which nutrients – and skin tightening and captured via photosynthesis – could be rapidly transported to depth, where carbon could be stored for the long term. But studying the creatures mixed up in DVM is tricky, because they often flee from whatever disturbs the water, or from light.
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“Each of the mechanisms that we think would frighten the animals, we looked to minimise,” says Dana Yoerger at Woods Hole Oceanographic Institution in Massachusetts, who developed Mesobot – which uses low-powered thrusters – along with his colleagues. “We made a thing that doesn’t disturb the water, doesn’t have bright lights, and doesn’t make a whole lot of noise.”
Using its attached red-light camera, Mesobot has the ability to get close enough to sea creatures without disturbing them, and will then monitor their movements over an extended time frame. “We’re trying to comprehend the daily life of the animals,” says Yoerger.
In California’s Monterey Bay, Mesobot was able to dive to a depth of 200 metres and film Solmissus , or “dinner plate” jellyfish in addition to giant larvaceans, which are filter feeders that appear to be a translucent pair of lungs. The robot tracked the jellyfish for 4 minutes, and a larvacean for up to 40 minutes, before it had to come back to port. Predicated on power consumption in these live missions, the team thinks Mesobot can track for a day without issues.
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“This is super exciting, from both a credit card applicatoin and a robotics perspective,” says Nick Hawes at the University of Oxford. “Understanding our oceans will play a key role inside our future sustainability goals. Their vastness and inhospitablity to humans means that our only solutions for large-scale, systematic investigations must involve robots in some way.”
Yoerger hopes to deploy Mesobot for longer missions that will provide us with an increase of information on the activity in the twilight zone.
Journal reference: Science Robotics , DOI: 10.1126/scirobotics.abe1901
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