A Wealth of Data in Whale Breath

http://www.nytimes.com/2013/10/01/science/a-wealth-of-data-in-whale-breath.html

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MYSTIC, Conn. — On her trainer’s command, an alabaster-skinned beluga whale named Naku placed her chin on the deck of her outdoor pool and exhaled several times, emitting a hollow “chuff” sound with each breath. The vapor rose into a petri dish a researcher held over her blowhole.

Those tiny drops contain a wealth of information, it turns out. Researchers at Mystic Aquarium and elsewhere are learning how to use the breath, or “blow,” of whales and dolphins to extract and measure hormones, microorganisms, DNA and the byproducts of metabolism.

Their goal is not only to improve the health of captive cetaceans like Naku, but also to develop a powerful, unobtrusive technique for studying them. While blood is the gold standard in physiological research, it can be hard to obtain — and all but impossible from large whales. Three new studies describe advances in breath analysis, which may prove to be the next best thing.

“I suspect that everything that’s in the blood is in the blow, just at much lower concentration, a little harder to measure,” said Kathleen Hunt, a research scientist at the New England Aquarium in Boston. “All kinds of goodies that we could learn a lot from that we’ve never been able to get from these animals.”

Doctors have long sniffed their patients’ breath to diagnose a variety of diseases. But gadgets may soon replace noses, with chemical breath tests under development for a host of human ailments, including asthma, cancer, diabetes and tuberculosis.

Trainers and veterinarians working with captive whales and dolphins also routinely smell their breath. Normal dolphin breath has a fishy smell; rotten-egg scents signal digestive problems, and sweet ones indicate bacterial pneumonia, according to Sam Ridgway, a veterinarian and neurobiologist at the National Marine Mammal Foundation in San Diego. In 1969, Dr. Ridgway published the first basic cetacean-breath study, exploring a dolphin’s diving ability.

Four decades later, advances in chemical sensing, computing and human breath analysis drew Dr. Ridgway’s team and perhaps a half-dozen others back to cetacean breath in earnest. In 2009, researchers reported detecting the hormones progesterone and testosterone in blow from humpback and North Atlantic right whales — potential clues to their sex and reproductive state. The paper, published in the journal Marine Mammal Science, showed that blow analysis might really work.

A few months later, another team using a remote-controlled helicopter to collect blow samples reported finding potentially pathogenic bacteria in the breath of five whale species. The whales watched the helicopter buzz overhead, but otherwise seemed unperturbed, said the lead researcher, Karina Acevedo-Whitehouse, a molecular epidemiologist at the Autonomous University of Querétaro in Mexico. “In terms of what we normally do with wildlife — restraint and capture and collecting samples — this is as noninvasive as you can get.” (The paper, published in the journal Animal Conservation, earned its authors the satirical but coveted Ig Nobel Prize from the magazine Annals of Improbable Research.)

After those papers, others dived in, several financed by the federal Office of Naval Research. Scientists at Mystic Aquarium are studying reproductive and stress hormones, as well as DNA, in the breath of Naku and her three poolmates. Not only do the four belugas blow on demand, but they also flop their tails onto the pool deck so researchers can draw blood and collect fecal samples. They open their jaws for saliva swabbings (and toothbrushings) — all in exchange for a few fish or some pats on their bubble-gum-pink tongues.

Being able to compare results from all four bodily fluids is a huge advantage in working out study methods, said Tracy Romano, the project’s leader. So is being able to monitor and control virtually every aspect of the belugas’ lives. “We know the health of the animals,” she said. “We know the age; we know what the animals are eating; we know the water chemistry.”

In San Diego, scientists at the National Marine Mammal Foundation are studying a group of highly cooperative dolphins trained to locate sea mines and swimmers for the United States Navy. Their breath has already yielded hundreds of compounds — a fortune in molecules.

“We looked at the samples and were like ‘All right!’ There is so much stuff in there,” said the study’s director, Cristina Davis, a chemical sensing expert at the University of California, Davis. “There’s a tremendous amount of room for discovery.”

The team is now scrutinizing the compounds for useful indicators of dolphin health. A paper in Marine Mammal Science takes a closer look at one, nitric oxide, which signals respiratory disease when elevated in humans and may do the same in dolphins.

Great whales are not so easily studied. They spend so much time offshore and underwater that even basic observation is difficult. Most species have failed to fully recover from centuries of whaling, and scientists suspect they are under stress from human-caused problems like pollution and overfishing of the whales’ prey. Blow testing, along with new techniques for analyzing skin and blubber biopsies, feces and photographs should help identify the culprits, according to a paper published in the journal Conservation Physiology.

Dr. Hunt of the New England Aquarium, the paper’s lead author, spent years studying hormones in the feces of terrestrial animals. She and her colleagues successfully translated those methods to large baleen whales, enlisting trained sniffer dogs to track down whale feces. But while “poop’s great,” Dr. Hunt said, “whales won’t poop on command.” Maybe not, but they do exhale frequently, in conspicuous sprays that have long beckoned whalers and scientists alike. In 2011, Dr. Hunt’s team went to the Bay of Fundy to streamline the system for collecting blow from endangered North Atlantic right whales.

The Mystic technique, placing Petri dishes neatly over blowholes, was not an option. “I’m fairly jealous of their belugas,” Dr. Hunt said. After much experimentation, her team settled on a cutoff Hawaiian Punch bottle stuffed with bridal-veil tulle at the end of a 32-foot pole, an apparatus that requires a synchronized shipboard ballet to operate smoothly.

Back at the lab, the team found a suite of hormones that may indicate the animals’ sex, maturity and reproductive status — along with cortisol, a hormone that tends to rise in conditions of stress and is considered a critical measure of an animal population’s health.

In a paper set for publication this month in Marine Mammal Science, Dr. Hunt’s team reports that a simple, portable, low-cost test can detect hormones in blow, which should open the field to any curious whale scientist.

Plenty of work remains. But Ari Friedlaender, a Duke University marine-mammal ecologist not involved in the studies, had nothing but praise for the new line of research. “The door is open for this work to be done in a lot of different places, on a lot of different populations,” he said.