The Green Party of Canada is calling for a ban on seismic testing by the oil and gas industry off the coast of Newfoundland and Labrador in the wake of data showing plunging plankton levels.

“There are clear signs that we need to make some serious policy adjustments,” Leader Elizabeth May said in a statement.

“In September, scientific research revealed that marine life in the Gulf of St. Lawrence is severely threatened. (These) findings on plankton provide further proof that we need to abandon our status-quo thinking about the environment and take steps toward restoring ecological balance.”

The call comes as scientists with the federal Department of Fisheries and Oceans (DFO) report a steady decline in phytoplankton and zooplankton levels. The tiny organisms live near the ocean’s surface and underpin the entire marine food web, feeding the smallest and largest of creatures that call the ocean home. Small but mighty, they are what make life on Earth possible.

What started off as a dip has become more profound, with values now about 50 per cent of what they were five years ago.

“That’s a substantial decline,” Pierre Pepin, a senior researcher with the department in St. John’s, N.L., told iPolitics. “And it’s not only a decline in the overall biomass; we’ve also seen a shift in the composition of the plankton.”

For fear of appearing alarmist or excessively precautionary, Pepin says more research is needed to determine if seismic testing is having an impact over the long term.

READ MORE: Calls to end seismic testing off NFLD and Labrador as plankton levels plunge

Others, however, including Dalhousie University’s Lindy Weilgart, say that, given all the stressors on the ocean, from pollution to absorbing most of the carbon dioxide humans are putting in the atmosphere, we no longer have the luxury of not being precautionary.

For 25 years, Weilgart has studied underwater noise. Last year, she produced a report that reviewed 115 primary studies of human-produced underwater noise sources affecting 66 species of fish, 40 species of marine mammals, and 36 species of invertebrates. It showed zooplankton suffer high mortality in the presence of noise.

An Australian study published in 2017 in the journal Nature found that seismic testing can destroy plankton populations.

The research by the University of Tasmania and Curtin University found that, within the 1.2-kilometre range sampled, air-gun signals that are commonly used in marine petroleum exploration can cause a two- to three-fold increase in mortality of adult and larval zooplankton.

“There is a significant and unacknowledged potential for ocean-ecosystem function and productivity to be negatively impacted by present seismic technology,” the authors found.

At the Federation of Independent Sea Harvesters of Newfoundland and Labrador (FISH-NL), President Ryan Cleary said his members see the impact every day on the water, which has led his organization to repeat its calls to halt the use of air guns.

With plankton stocks plunging while seismic testing goes through the roof off the coast of Newfoundland and Labrador — the term “super-sized” has been coined in recent years — Cleary says it’s “just too coincidental.”

“I don’t believe in coincidences. From my perspective, where there’s smoke, there’s fire.”

Seismic surveys produce the loudest human-made sounds in the ocean aside from explosions. The process involves towing air guns behind ships and shooting loud blasts of compressed air through the water and into the seabed to find oil and gas deposits that may be buried there. The guns release at high pressure and can go off every 10 seconds around the clock for months at a time. The sound can travel 3,000 kilometres.

“Seismic boats leave a trail of disaster in their wake,” said David Peters, the Newfoundland and Labrador representative on the Green Party’s federal council, the in a statement.

“After impact, they leave parts of the ocean barren. With a plankton decline, crab stocks are likely to follow. Seismic testing needs to stop.”

Although there are technological alternatives to the air guns that are quieter and safer, and may glean better geophysical information to find deposits under the ocean, the Canada-Newfoundland and Labrador Offshore Petroleum Board (C-NLOPB), which regulates the province’s offshore industry, has no plans to change its practice, nor mandate they be used.

A spokeswoman said there is “no conclusive scientific evidence” that would change its approach to authorizing seismic activity.

“The (C-NLOPB) appears to be rubber-stamping industry requests for seismic testing,” May said. “I will continue to press in the Senate for amendments to the Environmental Assessment Act, C-69, to remove any role for the offshore boards.”

In the United States, environmental groups are suing the Trump administration to stop seismic testing and offshore drilling along the Atlantic coast.

Earlier this month, Alan Wilson, South Carolina’s Republican attorney general, joined the suit — which now includes nine environmental groups and nine states — to halt permits for exploration.

Last week, a judge in South Carolina blocked the administration from processing seismic testing permits for offshore oil drilling until after the government shutdown.

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