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Toxins from oil spills and wildfires are found in killer whales and their offspring

In the pristine waters off the coast of British Columbia (B.C.), a concerning discovery has emerged. Researchers have found toxins in both Southern Resident and Bigg’s killer whales, shedding light on the unseen dangers lurking in our oceans.

This discovery marks the first time polycyclic aromatic hydrocarbons (PAHs) have been identified in orcas in these waters, revealing a direct impact on marine life from human activities.

Toxins called PAHs are harming killer whales

PAHs, a group of chemicals found in coal, oil, and gasoline, are ever-present in our oceans. Now, scientists have confirmed that these toxins are moving through food chains, ultimately accumulating in top predators like killer whales.

These compounds, known for their carcinogenic and mutagenic properties, enter the ocean through various sources, including oil spills, burning coal, and forest fires. The study’s alarming revelation that PAHs are transferring from mother orcas to their fetuses underscores the pervasiveness of this pollution.

Dr. Juan José Alava, the study’s senior author and a principal investigator at the UBC Ocean Pollution Research Unit, highlights the significance of these findings.

“Killer whales are iconic in the Pacific Northwest, playing a critical role culturally, economically, and ecologically. Their ability to metabolically process PAHs indicates recent exposures. These majestic creatures are like our ‘canary in the coal mine’ for oceans, indicating the health of our waters.”

Orcas and ocean health

The research team analyzed muscle and liver samples from twelve killer whales stranded between 2006 and 2018. Their findings were startling.

All samples contained PAHs, with one particular compound, C3-phenanthrenes/anthracenes, accounting for a significant portion of the total contamination. These results tell a story of an environment under stress, with implications that ripple through ecosystems and communities.

The contaminants varied between the two orca groups. Bigg’s killer whales, ranging from California to southeastern Alaska, showed signs of exposure to PAHs from burning coal and vegetation. In contrast, the Southern Residents, inhabiting areas closer to urban centers, bore the chemical signature of oil spills and fossil fuel combustion.

Source of toxins in killer whales

Kiah Lee, the study’s first author, points out the various activities contributing to this toxic load. “From oil pipeline developments to tanker traffic and forest fires, these sources introduce PAHs into the marine food web, ultimately affecting orcas, the apex predators.”

The presence of these toxins in such a critical species raises alarm bells for the health of the entire marine ecosystem.

Dr. Stephen Raverty is a co-author of the study and IOF adjunct professor and veterinary pathologist with the B.C. Ministry of Agriculture and Food. He emphasizes the limited population of Southern Residents and how pollution is one of the many threats they face.

“There’s only a small population to draw from — 74 individuals in the case of the Southern Residents,” said Raverty. “There are many potential causes for their decline, pollution being one.”

The case of ‘Luna’, an orca with a unique life history, highlighted how varied habitats can lead to a mix of hydrocarbon contaminants, further complicating the picture.

Conservation and action

Paul Cottrell from Fisheries and Oceans Canada sees this study as a vital step in understanding and managing the impacts on killer whale habitats. Baseline data on current PAH levels are essential for monitoring future trends and impacts.

“The preliminary findings from this study will add key information to inform management approaches in killer whale habitats,” said Cottrell. “The source of the PAHs is often from human activity and it is important we have baseline data on current PAH levels in killer whales to monitor those trends and impacts in marine ecosystems into the future.”

Dr. Alava concludes with a call to action. Reducing and eventually eliminating fossil fuel consumption is crucial not only for combating climate change but also for preserving marine biodiversity. This effort will benefit coastal communities and future generations, reinforcing the interconnectedness of our actions and the health of our planet.

In summary, this study is a wake-up call. It reminds us of the intricate connections within our environment and the responsibility we have to protect these majestic creatures and their habitats. The health of the orcas is a reflection of the health of our oceans, and ultimately, our planet.

The full study was published in the journal Scientific Reports.


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