The killer whales that stranded along the coast of northern Norway didn't die completely in vain. Researchers took valuable samples from them to measure the levels of chemical pollution in their bodies.
Among the unlucky whales to strand, was a young killer whale calf estimated to be just 10 days old. Analyses showed that not just the adult killer whales, but also this young calf had high levels of a range of harmful chemicals.
“He just had milk in his tummy, so all the chemical pollution in that baby must have come from the mother”, says Clare Andvik from the Department of Biosciences at the University of Oslo.
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He hadn't eaten anything but his mother's milk in his short life. All of the nutrition, and pollution, that he had in his body before he stranded must have come from either his mother's milk or whilst he was in the womb.
“The transfer happens both whilst the baby is inside the womb, through the placenta and umbilical cord, as well as through the milk after the baby is born”, says Professor Katrine Borgå.
“The chemicals that we know go most through the placenta and umbilical cord are low in the offspring. This suggests that the lipid rich milk, and transfer in fatty tissues, are what is most important”, Borgå says.
New chemicals behave like old ones
The researchers found large amounts of "old" chemical pollutants, chemicals that are already regulated, as well as new chemicals which are still in use without restrictions. This is the first time some of the newer chemicals have been proven to be transferred directly from mother to offspring.
“We knew that this transfer occurred with the old, banned chemicals. But now we have found that also these new chemicals, which are not regulated and still in use today, can be transferred via the mother's milk”, Andvik says to Titan.uio.no.
This research project began because the Norwegian Ministry of Climate and Environment wanted to find out if these new chemicals could be found in Norwegian whales. These toxic chemicals include new variants of so-called brominated flame retardants: chemicals that are added to plastics, electronics, and furniture to make them less flammable.
“The properties that mean we want to produce and use these chemicals are the same that means we can find them in the environment. They are chemically stable and break down slowly. Their chemical structure means that they can bioaccumulate in organisms.”
“They have been in use for a long time, but some of them have been banned and replaced with newer types of flame retardants. Now we have shown that these new chemicals behave in a very similar way”, says project leader Borgå.
“The new chemicals can also have toxic effects, especially on very young animals which are growing and developing”, Andvik says.
Just like with the old chemicals, the new chemicals have an affinity to the fatty tissues in the body. The thick fatty layer of blubber that surrounds whales is ideal, and high levels can accumulate in these species.
“The new flame retardants distribute in the body in a very similar way to the old chemicals”, Andvik says.
They saw this clearly in the young killer whale calf. From this individual, they were able to collect samples from a range of different organs.
“From the young whale, we have heart, spleen, kidney, liver, muscle and blubber. We can therefore also see how the chemical pollutants are distributed in the body and we found highest levels in the blubber and fatty heart”, Andvik says.
Chasing the industry
The term "chemical pollutants", or "environmental contaminants" include a range of different groups and substances, and they can affect organisms in different ways.
“High levels of these chemicals can lead to a weakened immune response in marine mammals. This means that they are more vulnerable to viruses and other illnesses. They have also been shown to adversely affect the reproductive system, disrupt hormones, and cause cancer”, Borgå says.
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Researchers are often chasing after the industry, as they steadily produce and use new chemicals which have not always been tested for their effects on wildlife.
“To ban a substance, we need good evidence that it is dangerous for humans and the environment. It is difficult for us when there are thousands of different chemicals. As soon as you ban one type, another chemical, which is very similar but has a new name, comes out on the market”, Andvik says.
According to Borgå, this is changing, at least in Europe.
“Now the industry themselves are required to prove that the chemicals they produce are not persistent, that they do not bioaccumulate in wildlife, and that they are not toxic. They must have all of this proof in place before they are allowed to produce and use the chemical.”
Norway is among five countries which is now hoping to ban a very large group of chemical pollutants called PFAS. These chemicals contain fluorine, and most are very persistent, can bioaccumulate in animals, and can cause harmful health effects.
“This is the first time that we are trying to ban such a large group of chemicals, instead of banning one chemical at a time”, Andvik says.
PFAS are used in, amongst other things, ski wax and Teflon frying pans. Researchers also found high levels of PFAS in the killer whale calf.
“Our results can be used as an argument for the regulation of PFAS. We can show that it is found in wildlife, despite the fact that unregulated chemicals are not supposed to be allowed to bioaccumulate or be present in animals”, Andvik says.
Old chemicals do not disappear
PCB is a notorious chemical in the history of chemical pollution. This is a group of chlorinated chemicals that are persistent, bioaccumulative and toxic.
“PCB has been regulated for over 40 years, but is still found in building materials and landfills. PCB is slowly but steadily leaching out into the environment. Even though in this project we were most interested in the newer chemicals, we also found high PCB levels in these killer whales. We are less than 20 percent of the way to our goal of removing PCBs from the environment”, Borgå says to Titan.uio.no
In the study, which is now published in Environmental Toxicolology and Chemistry, the killer whales get all the attention. But Borgå and Andvik's project contains a total of 10 different species of marine mammals. There will therefore come more results soon.
“We have just one individual of the young killer whale, but as a part of this project we have also included samples from the minke whale hunt in the Barent's Sea. From that, we have a better data set to look at the transfer of these chemicals from mother to offspring, as we have offspring from specific mothers. The results we have published now is just a taster for what is coming”, Borgå says.
They collaborate with Norwegian Orca Survey, which has collected all the samples from the stranded whales. Norwegian University of Life Sciences (NMBU), the Institute of Marine Research and NILU – Norwegian Institute for Air Research are also part of the team.
Not the reason for mass strandings
There may be several reasons why whales are stranding. Research from other parts of the world shows that most of them die at sea and then are brought ashore by wind, waves and ocean currents. Some have stranded alive because they are sick or too weak to fight the waves.
“The young killer whale we studied, stranded alive. The group had caught herring in a very shallow area, and somehow the calf was caught on a reef”, Andvik says.
In the spring of 2020, there came a wave of stranded whales along the Norwegian coast. The researchers therefore checked the levels in the stranded killer whales (collected 2015-2017) against living animals.
“We compared the levels from the stranded killer whales with the levels in biopsy samples from living animals from a previous project”, Borgå says.
They didn't find especially high levels in the stranded whales
“We therefore don't have documentation for that the stranded whales are more polluted than the living whales”, the professor says.
Scientific article:
Clare Andvik, Eve Jourdain, Jan L. Lyche, Richard Karoliussen og Katrine Borgå: High levels of legacy and emerging contaminants in killer whales (Orcinus orca) from Norway, 2015–2017, Environmental Toxicology and Chemistry, May 2021.
