Remote-Controlled Fish Tank Enables Scientists To Study Fish Without Them "Exploding"

Rapid decompression isn't pretty. Image credit: © 2018 Shepherd, Wandell, Pinheiro and Rocha. CC by 4.0

Despite making it to the challenger deep (an experience we discussed with explorer Richard Garriott) there is still much we don’t know about the ocean and it reveals more mysteries to us the deeper we go (sometimes with the help of alligator corpses). Unfortunately, a pesky thing called barotrauma makes carrying out thorough investigations of certain sea critters all the more difficult, as we can’t whisk them to the surface (where the pressure is considerably less than that in the deep ocean) without their bodies somewhat exploding. Ever wonder why the blobfish is so… blob-like?

Fortunately, scientists - being the clever clogs they are - were able to come up with a solution that was published in the journal Frontiers In Marine Science. By combining remotely operated vehicle (ROV) technology with our knowledge of the bends, a term given to the symptoms caused by experiencing a sudden reduction in pressure. The bends can affect scuba divers if they surface too quickly from their ocean adventure, but upon the land, we can treat these people in hyperbaric chambers where the air and oxygen can be altered to alleviate the symptoms. In humans, the bends can cause anything from joint pains and fatigue to loss of consciousness and death if not managed properly. Returning humans to low pressure from high pressure can have devastating consequences, as demonstrated by the Byford Dolphin Accident.

We already know animals can suffer the bends too, as it’s been seen in some whales who surface too quickly (potentially spooked by sonar testing or noisy ocean traffic). To keep their subjects safe, researchers created a portable, submersible hyperbaric chamber which they named the SubCAS. The nifty piece of kit was able to bring reef fishes from mesophotic depths (also known as "the twilight zone," approximately 60 to 150 meters (197 to 492 feet) inside a chamber that slowed the process of decompression. Of the 174 fishes enrolled in the experimental flight, 155 survived the decompression process.

A further investigation looked at how 148 specimens shipped to research centers and aquariums fared with being transported as air cargo, with 143 making the journey. This is a particularly poignant achievement as pressure decreases the higher you are in Earth’s atmosphere (which is part of the reason why your ears go funny on a flight). The bends in humans are sometimes the result of a person flying home too soon after having gone diving, so fish taking flight were exposed to an even greater difference in out-of-chamber pressure.


“The SubCAS has allowed us to reliably surface charismatic fishes previously unknown to science and maintain them in aquaria for research and public engagement purposes,” wrote the study authors. “This opportunity facilitates a direct connection between our more than one million annual visitors and the wonders of exploration and the science of mesophotic coral ecosystems.”


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