Aquatic life showing signs of improvement, 5 years after Lac-Mégantic oil spill

Five years after the Lac-Mégantic train derailment, aquatic life is steadily recovering even though the oil that seeped into the Chaudière River is still present, according to experts from Quebec's Environment Ministry.

More than six million litres of crude oil either burned or leaked into the environment on July 6, 2013, when a train carrying 72 tanker cars barrelled through the small town and exploded, killing 47 people.

Approximately 100,000 litres of oil ended up spilling into the Chaudière River and was swept downstream, covering the riverbed as far north as Saint-Georges-de-Beauce, according to Dave Berryman, a biologist with the ministry.

"It was a serious situation," said Berryman, who coordinated the governmental committee that conducted surveys of the river from 2013 to 2016.

While there wasn't a steep increase in mortality rates, the spill particularly affected the benthic community, small organisms that crawl and live over rocks and gravel.

''They were basically smothered by the oil that settles on the bottom sediments," Berryman said.

Despite an "impoverished community" in 2013, the invertebrates were already showing signs of recovery by 2014.

Two years later, only eight per cent of testing stations showed signs of oil sediments which surpassed acceptable levels.

"We are surprised, we didn't know what would happen," said Berryman.

Deformed fins

Fish mostly steered clear of the oil, which floated on the surface since it is lighter than water, Berryman explained.

"[The fish] could smell or taste the oil, and would swim elsewhere."

Nonetheless, fish abnormalities started climbing in the years following the disaster.

In 2014, less than five per cent of fish showed signs of deformities. By 2016, 25 per cent to 45 per cent of fish were affected, mainly by fin erosion, which is also observed after major oil spills in oceans, said Berryman.

"It's a common reaction for fish when they're exposed to oil," he said.

The next survey that will provide a portrait of the impact on fish and invertebrates will be held in 2022.

This will allow government experts to determine whether newer generations of organisms continue to be affected by the spill.

The ministry decided to suspend the annual surveys until then because oil levels were steadily decreasing.

"The river can clean itself," said Berryman. 

Meanwhile, sport fishing was never suspended, Berryman said, because oil is not absorbed by the flesh the way mercury or BPC contaminants are.