These killer whales exhale sickening germs | Science News for Students

These killer whales exhale sickening germs

In samples from whales’ blowholes, scientists found disease-causing bacteria and fungi
May 15, 2017 — 7:10 am EST
killer whales

These killer whales belong to a population off the west coast of North America, which is endangered with extinction. Researchers sampled the breaths of 12 whales in this group and found disease-causing microbes.

People usually try to give killer whales their space. Getting close to one’s blowhole is especially risky. But Canadian and America scientists got that close — and for a good reason. "We wanted to know what kind of fungi and bacteria they had in their breath," explains Stephen Raverty, who led the study. His team turned up germs, or microbes, that might cause disease. What they learned may help researchers protect these animals, which are endangered (at risk of extinction).

Raverty is a veterinary pathologist. That’s a scientist who studies animal diseases. He works for Canada’s Ministry of Agriculture in Vancouver, British Columbia. He and his team studied a population of endangered killer whales, or orcas. These are the biggest dolphins on Earth. The group  they studied lives off of the  West Coast of North America. Scientists call this population the southern resident killer whales. They migrate between California and British Columbia, depending on the season.

As of December 2016, there were only 78 whales left in this group. That’s down from 98, two decades earlier. Scientists hope to keep the population from shrinking even more.  Checking the whales' breath can give researchers a peak into the animals’ health.

The whales hold their breath while diving. When they surface, they exhale in a big burst from their blowholes. Afterward, they inhale fresh air.

The researchers used small motorboats to get within about 6 meters (20 feet) of the whales. By coming at them from the side or back, they didn’t get in the animals’ way or frighten them. When they were close enough, the researchers waved a 5.5-meter pole over a whale's blowhole as it surfaced.

The pole had five petri dishes attached to it. When researchers twisted the pole's handle one way, the lids on the petri dishes opened. This allowed them to catch liquid droplets and exhaled breath. When the scientists twisted the pole’s handle the other way, the lids closed again.

droplet collection
A researcher prepares to collect droplets and exhaled breath from the blowhole of a southern resident killer whale.
Jeff Foster

The team filled the petri dishes with the exhaled breath from 12 killer whales. In some cases, breaths from the same whale were sampled more than once between 2006 and 2009.

"The whales were very cooperative," says Raverty. "There was no evidence we scared them." Still, it took the researchers four years to fill their petri dishes 26 times. 

The exhaled breaths did host disease-causing fungi and bacteria. Those microbes would have been living in the whales’ lungs.

The team shared its findings March 24 in Nature Scientific Reports.

It's normal for certain microbes to grow in the lungs of whales, people and other animals. In fact, microbes live all over our bodies, inside and out. Most of them don’t cause disease. But some can make us sick, especially when they get too plentiful.

The whales may have picked up the disease-causing germs during their migration up and down the coast. "They swim past many populated areas and farms," Raverty notes. City sewage containing urine and feces can seep into the ocean. Rains can run off of farm fields. This runoff may pick up chemical fertilizers that had been used to help plants (and microbes) grow. Some fertilizers contain animal manure, which may have contained microbes. Both sewage and farm runoff, therefore, could easily wash microbes into the sea.

Just because the whales have disease-causing germs in their breath doesn't mean they are sick or will become so. But it does mean researchers should watch these animals closely for signs of illness — especially since there are so few of the whales to begin with.

Stressed swimmers

The southern resident killer whales are under a lot of stress. And that worries researchers. After all, stress can weaken an animal and make it less able to fight off disease.

These killer whales face three main stresses, Raverty notes. One is food. There are fewer fish to eat along the coast these days — especially salmon, the whales’ favorite meal. This means the whales sometimes go hungry. Water contaminants are a second stressor. These include toxic chemicals from oil spills and wastes that pour into the water from the land. Lastly, there are a lot of boats traveling up and down the west coast of North America. Some are large fishing boats. Others carry cargo or tourists. All of that traffic and noise can stress out animals that live in the ocean.

Over the years, some killer whales from the group that the Vancouver team studied have died after stranding themselves on beaches. When Raverty and others analyzed the whales’ lungs, they found the same disease-causing bacteria and fungi that have now turned up in the breaths of live whales.

These include bacteria called Staphylococcus aureus (STAF-uh-lo-KOK-us OAR-ee-us). This germ is a common cause of lung and skin infections. Raverty suspects the whales that died were victims of lung infections. These animals were probably already weak from stress and couldn't fight off the infectious germs.

Raverty’s team now worries that if other whales in the population are very stressed, they too might sicken and die.

For now, researchers have a baseline of data on the type and number of potentially disease-causing germs these whales host. The next time they take a sample, the researchers can compare it to these. This will make it easier to judge the whales' health, says Joe Gaydos. He is a wildlife veterinarian who specializes in killer whales. He works at the University of California, Davis.

"Killer whales are amazing animals, but it is very difficult to assess the health of free-ranging killer whales," he says. "One day we may be able to capture a breath sample and not only tell what type of bacteria the whale has in its lungs, but also its state of nutrition and general health."

Power Words

(more about Power Words)

agriculture     The growth of plants, animals or fungi for human needs, including food, fuel, chemicals and medicine.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

contaminant     Pollutant; a chemical, biological or other substance that is unwanted or unnatural in an environment (such as water, soil, air, the body or food). Some contaminants may be harmful in the amounts at which they occur or if they are allowed to build up in the body or environment over time.

data     Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning.

endangered     An adjective used to describe species at risk of going extinct.

feces     A body's solid waste, made up of undigested food, bacteria and water.

fertilizer     Nitrogen, phosphorus and other plant nutrients added to soil, water or foliage to boost crop growth or to replenish nutrients that were lost earlier as they were used by plant roots or leaves.

germ     Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.

host     (in biology and medicine) The organism (or environment) in which some other thing resides. Humans may be a temporary host for food-poisoning germs or other infective agents.

infection     A disease that can spread from one organism to another. It’s usually caused by some sort of germ.

infectious     An adjective that describes a type of germ that can be transmitted to people, animals or other living things.

killer whale     A dolphin species (Orcinus orca) whose name means whale killer. These animals belong to the order of marine mammals known as Cetacea (or cetaceans).

manure     Feces, or dung, from farm animals. Manure can be used to fertilize land.

microbe     Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

migrate     To move long distances (often across many countries) in search of a new home. (in biology) To travel from one place to another at regular times of the year to find food or more hospitable conditions (such as better weather). Species that migrate each year are referred to as being migratory.

nutrition     (adj. nutritious) The healthful components (nutrients) in the diet — such as proteins, fats, vitamins and minerals — that the body uses to grow and to fuel its processes.

orca     A large species (Orcinus orca) of black-and-white porpoise. Also known as the killer whale.

pathologist     Someone who studies disease and how it affects people or other infected organisms.

population     (in biology) A group of individuals from the same species that lives in the same area.

resident     Some member of a community of organisms that lives in a particular place. (Antonym: visitor)

runoff     Rainwater that runs off of land into rivers, lakes and the seas. As that water travels through soils, it picks up bits of dirt and chemicals that it will later deposit as pollutants in streams, lakes and seas.

sewage     Wastes — primarily urine and feces — that are mixed with water and flushed away from homes through a system of pipes for disposal in the environment (sometimes after being treated in a big water-treatment plant).

Staphylococcus aureus     (also known as staph) A species of bacteria that is responsible for a number of serious human infections. It can cause surface abscesses, or boils. If it gets into the bloodstream, where it can be carried throughout the body, it also may cause pneumonia and infections of the joints or bones.

stress     (in biology) A factor, such as unusual temperatures, moisture or pollution, that affects the health of a species or ecosystem.

toxic     Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.

veterinarian     (adj. veterinary) A doctor who studies or treats animals (not people).

waste     Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.

whale     A common, but fairly imprecise, term for a class of large mammals that lives in the ocean. This group includes dolphins and porpoises.


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Journal: S. Raverty et al.  Respiratory microbiome of endangered southern resident killer whales and microbiota of surrounding sea surface microlayer in the eastern North Pacific. Nature Scientific Reports. Published online March 24, 2017. doi:10.1038/s41598-017-00457-5.