Canadian Study Examines Impacts Of Dilbit Spills On Fish Survivability

There are more than 185,000 miles of liquid petroleum pipelines in the U.S., many of which transport bitumen diluted with chemical solvents, a material known as dilbit. While these pipelines are designed to move petroleum more safely than a tanker or similar vehicle, accidents still happen, as in the case of the 2010 dilbit spill on the Kalamazoo River in Michigan. A 40-foot segment of pipe carrying dilbit from Canadian tar sands suddenly ruptured, spilling more than 800,000 gallons of petroleum that took years to clean up.

With North American oil production on the rise, more of these pipelines are being installed to support increased dilbit transport — all the while, leaks are occurring more frequently. A new study from Queen’s University and the Royal Military College of Canada examines how dilbit spills affect fish populations.

The researchers found that toxic concentrations of dilbit can cause exposed fish to develop physiological and genetic deformities, such as abnormal swim bladders. Without a properly functioning swim bladder, fish can have trouble avoiding predators and catching prey.

In the study, the embryos of Japanese medaka were exposed to Access Western Blend dilbit for 17 days. While the dilbit didn’t have immediate lethal effects, the deformities caused by the toxic material can be a death sentence to fish in the wild, and drastically lowers survival rates. The study’s full findings are published in the journal Aquatic Toxicology.

Going forward, the Canadian research team plans to study how dilbit exposure impacts the survivability of native fish in their country. Peter Hodson, one of the team’s researchers, has been tasked to study the effects of dilbit on habitats containing sport fish such as salmon, trout, char, whitefish and graylings.

Researcher Barry Madison works with the fish exposed to dilbit. (Credit: Queen’s University)