The images show a disturbing array of debris on the ocean floor: white plastic shopping bags, a tire encrusted in barnacles, rubber lobster bands, garbage bags buried in sandy grit and a derelict lobster trap housing a lone moon snail.
The items were all captured on video by researchers at Dalhousie who, along with the Applied Oceans Research Group at NSCC, Fisheries and Oceans Canada and the Full Bay Scallop Association, scanned the bottom of the Bay of Fundy over a three-year period.
Their work, published Thursday (Nov. 14) in the Marine Pollution Bulletin, provides the first estimate of how much garbage and lost or discarded fishing gear litters the ocean floor in eastern Canada and it’s not good.
Significant and widespread
Tony Walker, a professor in Dalhousie's School for Resource and Environmental Studies, and lead author Alexa Goodman, a Dalhousie researcher in the Marine Affairs Program, found 47 items of debris from 26 camera stations.
If upscaled to cover the entire 13,500 square kilometres of the bay, the team estimated there could be 1.8 million pieces of garbage on the seafloor of one of the region’s most productive and lucrative fishing zones.
“This baseline study highlights that just because it is out of sight, benthic marine debris pollution is still evident in the Bay of Fundy, which is such a biologically significant area,” Dr. Walker said.
“It also provides useful information for government and other stakeholders to develop policies and strategies to reduce sources of benthic marine pollution.”
The researchers from Dalhousie, the Nova Scotia Community College and Fisheries and Oceans Canada, used a system of high-powered lights and an ultra-high definition camera that trailed behind a fishing vessel to record footage from the seafloor. The drift transects were taken over a three-year period at 281 different locations in the bay in 2017, 2018 and last July.
The team reviewed the 33 hours of video footage and quantified the items, putting them into three categories. Plastic made up the majority of debris at 51 per cent, while 28 per cent of it was comprised of fishing gear and 21 per cent was made up of other materials, such as cables, metal and tires.
“Based on these findings, seafloor debris in the Bay of Fundy is numerous and widespread,” the paper states.
“Debris stranded on the seafloor in the Bay of Fundy and elsewhere remain problematic, because plastic debris continues to fragment into secondary microplastics.”
Fishing gear and other debris
Most of the debris was found within nine kilometres of the shoreline and much of the material found on the periphery of fishing areas was fishing gear, including rope, bait bags, traps, gloves and blue lobster bands.
One station found 12 garbage bags partially buried in the sand, which the authors suggest may be the site of a marine dumping ground.
Dr. Walker says there was little evidence that the discarded items were harming the seafloor or leading to so-called ghost fishing, when lost gear continues to catch and kill marine species.
The findings align with similar studies in other parts of the world that found plastics to be the most prolific source of marine debris.
Italian researchers recently published a paper on work they did in 2016 involving a remotely operated vehicle that scanned the seafloor just off mainland Italy. They filmed four submarine channels, finding that plastic made up almost 70 per cent of the debris on the ocean bottom. Plastic bags were the most common type of litter.
The perils of plastic
Dr. Walker says the findings reinforce the need to cut down on the amount of plastic waste that ends up in the marine environment.
“The estimate of abundance provides valuable information for governments to implement management strategies to reduce plastic and other kinds of benthic marine pollution at source,” he says.
“If we’re going to walk the talk, we have to clean up our own shop. We’ve always prided ourselves on good waste management, but we may not be doing as good a job as possible.”
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