Weaker penis bones in river otters linked to oilsands contaminants in new study

“We’ve demonstrated how the bone health measure, the penis bone, is tied to exposure to certain trace elements and to hydrocarbons,” said Philippe Thomas, a wildlife toxicologist with Environment and Climate Change Canada.

The male river otter has a penis bone, or baculum, that is typically long, curvy and slender. The study says river otters are considered a “sentinel species” — one which can register the effects of environmental contaminants before other species.

Brittle penis bones could impair the species’ ability to reproduce, affecting other species up and down the food chain.

With the help of local trappers, researchers analyzed river otter livers and their penis bones. The specimens came from a range of locations both close to and far away from oilsands sites in Alberta.

“We do find, for the most part, that [the] river otter baculum is stronger, stiffer and denser at the low impact of those control sites — so in areas with usually lower levels of some of these hydrocarbons,” Thomas said.

While the discovery of weaker otter penises may stand out, the study also found that the presence of some contaminants — strontium, iron and the hydrocarbon retene — was associated with stronger penis bones among some otters. The former two elements are naturally occurring and retene is a byproduct of forest fires.

The study, Co-exposures to trace elements and polycyclic aromatic compounds impacts North American river otter baculum, appeared in the peer-reviewed scientific journal Chemosphere this month.

‘There were a few jokes’

Much of the research was conducted at a McMaster University lab that typically studies human bone injuries, not animal penises.

“It was a new area of research for my lab group, certainly,” said Cheryl Quenneville, an associate professor in mechanical and biomedical engineering at McMaster. “I have to admit there were a few jokes flying around.”

Along with measuring and scanning the bones, Quenneville and her team also conducted destructive and non-destructive mechanical tests.

Quenneville acknowledged that one of the tests her lab conducted might make some cringe — they tested how much force it would take to break the penis bones.

“I should be more sensitive to the way I speak about this,” she said, apologizing. “Certainly, we like to say we are trying to help the otters one at a time, trying to ensure their reproductive success.”

Thomas said past studies of mice and polar bears have shown that mammals with weaker penis bones tend to produce fewer offspring, or none at all. He said he only thought to study otters after he heard concerns from Dene and Cree hunters and trappers living in northern Alberta.

“We were given information by those land users saying that they were seeing reduced litter sizes, fewer pups … at some of these traplines,” he said. “So they were concerned that there might have been a reproductive failure.

“So we did a bit more digging around.”

In Fort Chipewyan, Alta., one of the communities closest to the oilsands, the head of a community-based environmental monitoring program for two First Nations said the new research validates what Indigenous elders have been observing for years — the collapse of wildlife numbers as oilsands production increased.

“[Thomas] applied science to a puzzle put to him by the elders,” said Bruce Maclean, a coordinator of community monitoring for the Athabasca Chipewyan and the Mikisew Cree First Nations.

Thomas’s study forms part of the joint oilsands monitoring program that’s been spearheaded by the region’s Indigenous communities and the governments of Alberta and Canada for almost a decade.

Thomas said he recognizes that studies like these often become highly politicized and weaponized on news and social media feeds by people for and against the oilsands. He added that the industry listens to reputable science and has responded in proactive ways in the past when their practices have been shown to be harmful.

These new findings and further research could help oilsands operators find new ways to phase out or limit exposure to by-products of their operations, he said.