Nfld. & Labrador

Is seismic testing to blame for disappearing plankton? This scientist says it's possible

Biologist Lindy Weilgart says we need more studies done on how seismic testing affects marine life before the province's push to double offshore oil production.

We need more information on how the tests affect marine life, says Halifax biologist

A Halifax biologist says seismic blasting could be behind the province's massive decline in plankton populations. (Wikimedia Commons)

Scientists have noticed a mysterious population crash in some of the Atlantic Ocean's tiniest and most important species, and a Halifax biologist says oil and gas exploration may be to blame.

Plankton and zooplankton are eaten by everything from small fish to massive whales and make up the base of the ocean's food system.

The tiny organisms are disappearing from Newfoundland and Labrador's waters, and Lindy Weilgart says blasts from seismic air guns have been shown to wipe them out.

"Before the science is even in, these petroleum boards are allowing seismic surveys to proceed," she told CBC's On The Go.

Over the past few years, phytoplankton and zooplankton populations have been cut in half, according to studies done locally by scientists from Fisheries and Oceans Canada. There's no clear answer yet as to why the numbers are falling.

On the other side of the world, Australian scientists first found that testing with seismic air guns destroys plankton a few years ago. The blasts from the guns send sound waves pulsing through the water and into the sea bed, giving oil companies a detailed look at what lies within the rock.

Phytoplankton use energy from the sun and convert it into food for the entire food chain, including fish. This makes them the primary producers of biomass in the oceans. (Victor Manuel Galvan/Puntacana Ecological Foundation/Associated Press)

 

Weilgart said the blasts can be more than 250 decibels.

"That is the loudest human-made sound apart from nuclear and very large chemical explosions," she said.

The Australian scientists found that an air gun decimated the zooplankton within a 1.2 km range of an experimental blast.

Weilgar says their work does not bode well for Newfoundland and Labrador, especially with the government's eyes on doubling oil production by 2030.

"Any time you're killing off large amounts and many species of zooplankton, that can't be good," she said.

Mitigating climate change impacts

The tiny organisms not only support life in the ocean, they help support life on earth, she says.

"These phytoplankton ... are what are absorbing most of our greenhouse gases," she said. "[They're] the whole reason that we're not burning up more than we are from climate change."

Measuring 5 mm or less, phytoplankton contain chlorophyll to capture sunlight and use photosynthesis to turn it into chemical energy which is later eaten by ocean creatures. (Photo courtesy of DFO)

Science doesn't yet know for sure why the blasts kill the plankton, she said, but one guess is that the tiny, sensitive plankton bodies are destroyed by the resonance.

"These are incredible acoustic pressure waves, right? It's different from a shock wave ... but they're not that different," she said.

Questions in the House of Assembly

Jim Dinn, the NDP's environment critic, fired off pointed questions about the issue in the Newfoundland and Labrador House of Assembly in June.

Natural Resources Minister Siobhan Coady responded, saying the practice has no effect on sea life.

"That is categorically false," Weilgart said. "To conclude there's no impact is absolutely false, very misguided and scientifically invalid."

Read more articles from CBC Newfoundland and Labrador

With files from On The Go

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