Marine scientists used hydrophones, or underwater microphones, and were able to pick up a mysterious humming sound about 1,000 feet deep in the Pacific Ocean, which might shed some light on the lives of marine creatures, according to a new research.
For some time, scientists were uncertain what exactly was making the elusive sound, since it did not resemble the clicking of underwater creatures, like dolphins, nor the mating call of humpback whales. The sound usually occurred a few hours after sunset and then for another few hours at dawn, the scientists said.
Simone Baumann-Pickering, a marine biologist at the Scripps Institution of Oceanography at the University of California in San Diego, stated that the sound was similar to the humming and buzzing you might hear while being on an airplane.
Dr. Baumann-Pickering and her colleagues said that the strange sound was eventually linked with the migration of billions of fish, squid and crustaceans – which all swam from the depths of the Pacific Ocean to the surface of the water at night. According to Baumann-Pickering, this migration might be the biggest one of vertebrae animals worldwide, as the combined weight of the migrating creatures is about ten billion tons.
Scientists suspect that the sounds could be made by the fish which are buzzing and humming to communicate. However, another hypothesis is that the animals are in fact just passing gas, the Dr. Baumann-Pickering said.
Some fish are known to emit gas when they swim from the depths of the ocean to the surface (and vice-versa); they have gas in their bladder that helps them control their buoyancy, the scientists noted.
Other researches, along with Dr. Baumann-Pickering and her team, will continue to look into the mysterious sounds coming from the depths of the ocean. That could also help better understand how deep-sea creatures communicate and live.
David Gallo, an oceanographer at Woods Hole Oceanographic Institution in Massachusetts, said that not much is known about that part of the world and that the new researcher was extremely fascinating.
Currently, many scientists are studying underwater sounds. It has been shown that man-made noises in the ocean – coming from gas and oil exploration, ship traffic, military sonar, and so on – is affecting the marine creatures. For instance, the hearing of whales can be damaged due to human activity in the ocean because it obstructs the animals’ tactics, according to previous studies.
The clicks and cries of whales play a key role in their survival. When they are looking for food, or when they communicate with each other, whales tend to generate certain sounds. They also do it when they travel to and from breeding ground, or when they are trying to drive away prey, the scientists explained.
Rob Williams, a marine conservation biologist for Seattle-based Oceans Initiative, said that ocean noise is present everywhere, and it represent a habitat-level stressor. This human-made noise might be changing the way that ecosystems function, Dr. Williams added.
Dr. Baumann-Pickering presented the new research at the Ocean Sciences Meeting that was held in New Orleans.
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