Biologists are pulling dolphins over and giving them breathalyzer tests—and not because they’re high on puffer fish.
Breath analyzers have long been used to catch drunk drivers. Now scientists have created one for dolphins to monitor their health and, by extension, the condition of the ocean, without the need to perform invasive procedures like taking blood and tissue samples from the marine mammals.
The researchers studied 13 captive bottlenose dolphins at the United States Navy Marine Mammal Program in San Diego and 21 wild dolphins in Sarasota Bay, Florida. The scientists used a special device that they placed over the dolphins' blowholes to capture five to 10 breaths in fewer than five minutes. The condensate is then frozen for later analysis.
As it turns out, dolphins are the perfect species for breath testing: They exhale a 20 liters of carbon dioxide with each breath and exchange 70 percent to 90 percent of their total lung capacity in just 0.3 seconds.
The scientists looked at the compounds contained in the breath at different times of day, such as when the animals had just eaten or were fasting, to establish baseline values for dolphins.
So just what is in dolphin breath? For one thing, a mixture of compounds that can be good markers of what’s going on in their blood. The researchers have identified more than a thousand substances in dolphin breath, including organic compounds, viruses, and lipids, according to a study published Wednesday in the journal Analytical Chemistry.
Now they also know what makes dolphin breath smell, well, fishy, having identified the exact compounds responsible for the odor.
More important, the researchers found indicators of human-made toxins in dolphin bodies, such as phthalates, which are used to make the plastic that so pervasively pollutes the oceans.
“Dolphin health is a good window into understanding how the changing ocean is impacting mammals,” said Stephanie Venn-Watson, director of the Translational Medicine and Research Program at the National Marine Mammal Foundation, which participated in the study.
That’s because dolphins are top predators, and ocean pollution makes its way up the food chain and into their bodies.
The researchers are working on whittling those 1,000 compounds in dolphin breath down to a handful that would indicate if an animal is healthy.
“Ideally there would be a handheld sensor to be used, similar to a breath test for alcohol in humans,” said Venn-Watson.
Over time, that could help scientists design personalized medicine for dolphins and monitor the oceans for pollution or invasive species.
The researchers are now trying to determine how much variability is in each dolphin breath depending on the time of day, the animal’s age, and health.
“Every day, even at different times, our own breath profiles can change so much that it is difficult to use it for things beyond breath tests for alcohol,” said Venn-Watson.
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