Dolphins have their own way to avoid decompression sickness, also known as "the bend," when diving. According to a study, they actively slow down their hearts before diving and adjust their heart rates, depending on how deep they plan to dive. The study provides new insights into how marine mammals successfully dive, avoiding the bend.
Unlike dolphins, humans cannot do that so they have to avoid surfacing too quickly because a sudden pressure drop would make the nitrogen bubbles pushed into their airways and cause joint pain or paralysis.
Andreas Fahlman at the Oceanographic Foundation in Valencia, Spain said that marine mammals like dolphins did not have this problem. Researchers are assessing this claim and decided to test it.
Dolphins vary their heart rates to conserve oxygen during dives
The researchers trained three bottlenose dolphins to hold their breath for different lengths of time: a long breath-hold, a short one, and another where they could do what they want. Dr. Andreas Fahlman of Fundación Oceanogràfic, Valencia, Spain explained that the heart rates of the dolphins lowered before or immediately as the dolphins began to dive.
Additionally, the researchers observed that the dolphins would reduce their heart rates faster and further when they prepared for the long-breath-hold, compared to the other two time lengths.
According to Science Daily, the results reveal that dolphins and perhaps other marine mammals alter their heart rate depending on the planned dive to reduce how fast they breathe.
In that way, they could conserve their oxygen during the dives. This could be the key to avoid dining-related problems like decompression sickness or also known as "the bends," Fahlman said.
Importance of understanding the dolphin mechanisms when diving
The researchers said that learning how marine mammals dive safely is the key to mitigate the health impacts of man-made sound disturbance to these animals.
"Man-made sounds, such as underwater blasts during oil exploration, are linked to problems such as "the bends" in these animals," Fahlman said.
He added that this knowledge would help in avoiding sudden loud disturbances and instead slowly increase the noise level to cause minimal stress on marine mammals. In short, the research may provide a very simple way for humans and marine animals to share the ocean.
New Scientist reported that the stress caused by the noise from the sonar or machinery used for oil extraction may interfere with the dolphins' conscious effort of controlling their heart rates, therefore increase their chances of getting the bends.
Scientists have long tried to measure the heart rates of dolphins but they were prevented by the practical challenges of measuring them. The researchers noted that learning more about the physiology of dolphins, and possibly other marine mammals, might be the way to mitigate decompression sickness problems among these marine mammals.
The researchers published their study in Frontiers in Physiology.
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