The first survey of Casco Bay for microplastics, the troubling, hard-to-see fragments of consumer products that are mysteriously showing up in waters around the world, found the shreds of plastic in four locations, with the highest concentration in busy Portland Harbor, according to new data compiled by the Friends of Casco Bay and shared with the Press Herald.

The nonprofit regularly monitors water quality in the bay but had never before looked specifically for microplastics, which have also been found in freshwater lakes, rivers and streams, much to the alarm of scientists and environmentalists. Typically defined as smaller than 5 mm, microplastics are also airborne. These bits and pieces of plastic waste, appearing variously as fibers, films and fragments, are difficult to trace to any source (beyond man).

The Casco Bay survey didn’t try to determine what the plastic might once have been or where it came from, although fishing gear and trash thrown in the water are always possible culprits for plastics found in the ocean. It was simply a counting game, step one in a scientific process still in its early stages.

Multiple factors make the presence of microplastics in the environment troubling. They’re small enough for marine life – or a human – to ingest without even noticing. A Maine-based study in 2014 found microplastics in blue mussels and oysters, for instance. These tiny bits of plastics also attract and hold other toxins.

Their potential to do harm to humans is still under study; microplastics are relatively recent area of scientific research, and while much data gathering has been done in the last decade, many unknowns remain.

“It’s a new field, a breaking field,” said Susan Shaw, the founder and executive director of the Blue Hill-based Marine & Environmental Research Institute, which has studied the issue of microplastics since 2012, including how microplastics accumulate in bivalves like mussels and oysters. “Certainly at the bottom of the food chain they are able to accumulate. That is compelling, and it is driving the field. People are worried about, ‘Where is it going in my body? Do I eat and excrete it?’ ”


Ivy Frignoca, the group’s Casco Baykeeper, and research associate Mike Doan began planning to survey Casco Bay for microplastics over a year ago, not long after Frignoca took over the position from longtime baykeeper Joe Payne. Marine debris – like fishing gear and floating trash – have already gotten a lot of attention, Frignoca said, but not microplastics. She and Doan knew it was highly unlikely they’d pull up plastic-free samples; researchers around the globe have found an average of 8 to 10 pieces of microplastic per liter in both ocean and fresh waters around the globe.

The Marine & Environmental Research Institute has been conducting regular studies in Blue Hill Bay and studies have also been completed in the waters off Nova Scotia, but until last summer’s survey, no one had tested for microplastics in Casco Bay.

Frignoca and Doan said their findings were slightly lower than they, or other researchers they consulted, expected.

“But this sort of sampling is incredibly variable,” Doan said. “If we went out a week later we might have found completely different numbers. I think the most important message is we found microplastics, just by taking a sample of water, in every region.”

Most of what the survey found were pieces of plastic fiber, predominantly blue, and 95 percent of them were less than 1.5 mm in length. “Ultimately, from the scientists’ point of view, there are still more questions than there are answers around microplastics in the aquatic environment,” said Abby Barrows, a microplastics researcher and scientist who runs a lab in Deer Isle and processed the samples for Friends of Casco Bay this fall.

Only one question has a definitive answer; these fibers and fragments all come from man-made materials.


“The reality is, we live in such a plastic age,” Barrows said. “It is going to be affecting us and we’re not sure on what level.”


Working over the course of two days, staff and volunteers from Friends of Casco Bay traveled as a group on June 15 to three locations: Portland Harbor, the waters off Cousins Island, and Halfway Rock. The next day, Frignoca and an intern went to Middle Bay in Brunswick, along with Brunswick Marine Warden Dan Devereaux, to take the final sample near Paul’s Marina.

They made sure they were wearing only natural fibers, namely cotton (wool would also be fine; both are organic and fibers will break down over time). They left their fleece pullovers and vests at home; fleece is made from synthetic fibers and has been shown to contribute to microplastic waste, a problem acknowledged by manufacturers such as Patagonia. L.L. Bean spokeswoman Carolyn Beem said the company is working on ways to mitigate the issue, ranging from using higher-quality fabrics to reduce shedding and adding odor-reducing properties to garments so they don’t have to be washed as much.

“We are making progress,” Beem wrote in an email. “But there is certainly more to be done.” The company takes the issue “very seriously,” she said.

So did the survey group from Friends of Casco Bay.


“We were as rigorous as we could be,” Frignoca said. “We were not going to contaminate the samples.”

They dipped in a 2-liter metal cylinder to gather water from the bay, turning the boat in each location to gather four samples from each region. Not every sample included microplastics, but within each region, at least two pieces of microplastics were found. They also turned up many cotton fibers in the samples.

“We didn’t have any preconceived notions of going after any targeted sources,” Frignoca said, meaning industrial sources or areas where runoff from human activity might be expected to be particularly high. The exception was Portland Harbor, obviously a busy location for fishing traffic, freight and cruise ships. “The goal was to get an overall look at the bay and a nice broad representation.”

She and Doan will be comparing notes with staffers from the Marine & Environmental Research Institute in coming weeks as well as using the data to support legislation aimed at curbing marine debris, which is sponsored by Rep. Mick Devin. An earlier bill sponsored by Devin died in the legislature last year, but Devin said a public hearing is tentatively scheduled on Feb. 5 to discuss the issue.

Friends of Casco Bay research associate Mike Doan and intern Emily Haggett sample Casco Bay for microsplastics. One heartening piece of the Casco Bay findings was that lab tests turned up no microbeads, the tiny plastic pellets found in exfoliating products that were banned in Maine in 2015.

One heartening piece of the Casco Bay findings was that lab tests turned up no microbeads, the tiny plastic pellets found in exfoliating products.

Microbeads were banned in Maine in March 2015, a move Friends of Casco Bay advocated for, and then later that year, federally as well.



But the microbead ban didn’t even come close to settling the microplastics problem, said Madelyn Woods, who has been leading the Marine & Environmental Research Institute’s research into microplastics in Blue Hill Bay (Barrows started the research before moving on to work with Adventure Scientists and start her own lab). “People in general think that is it and they have done their bit,” Woods said. “But in fact, that was only the beginning. We have only just seen the underside of the iceberg so to speak.”

Woods collaborated on a study with Bigelow Laboratory scientists in 2017 that focused on how mussels process microplastics.

“We fed them microplastics,” Woods said. “We found they can ingest large amounts.”

Almost 2,000 pieces of microplastics can go through their systems in a day, she said.

“They could pretty much take in microplastics as fast as we could feed them,” she said.


Then they looked at how the mussels excreted the microplastics and found that it took hours, if not days, to get them out of their system. After 72 hours of filtering water, dissected mussels still had traces of microplastics in their systems.

The scientists chose mussels, she said, because they are established water quality indicators. “We use them as health indicators, basically.”

The surveys conducted by the Marine & Environmental Research Institute have evolved over the years to try to answer some of the many questions about microplastics. In 2014, for instance, researchers targeted 20 different sites, trying to determine whether densely fished areas, like the waters around Stonington, would have higher concentrations of microplastics.

“In fact, that is not what we found,” Woods said.

That might be because fishing gear, a likely suspect for shedding plastic fibers, is so waterlogged that it doesn’t shed as fast as one might expect, she said.

Next the institute began studying different depths to see what impact temperature and salinity shifts, say from winter storms and spring thaws, might have on the way microplastics congregate. At a depth of 9 feet, she said, they found 15 pieces of microplastic per liter, versus an average of 10 in other areas.


Last summer, the institute increased its sampling areas to 180 sites around Blue Hill Bay, the first year of a three-year study. It’s also beginning a collaboration with Sewanee: The University of the South, to study the impact of microplastics on marine mammal tissue, including pilot whales and orcas from the Caribbean and harbor seals and minke whales from Maine. In this case, Woods said, the marine mammals will stand in for humans.

“The number of studies that look into the human health effects of ingesting microplastics are just not there,” Woods said.

If microplastics are everywhere, from the air to the ground, are they worse in the ocean?

“The thing that makes it troubling about the ocean is that there is no end cycle in the ocean,” Woods said. Benthic creatures can consume the plastics, then in turn feed marine life higher up the chain and eventually that can end up on human plates.

While the data set from Casco Bay is relatively small compared to other surveys, including last year’s in Blue Hill Bay, those who have been working in the field for years have already saluted the effort.

“All the data is important,” said Susan Shaw. “This research is helpful in creating public awareness that there is a problem and that you can’t see it.”


Barrows said future studies of Casco Bay could include more regions and more samples. But she cautioned that plastic pollution is variable.

“Concentration levels are driven by a complex mix of different factors,” she said, among them runoff, snowmelt and currents. With big pieces of marine debris, such as buoys and plastic bottles, it’s easy to see how much – and how far – currents and tides move pollution around. As the data collects, scientists can start looking at ways to mitigate the microplastics and how it moves.

“For me, there is a whole realm of ocean questions, toxicological and fisheries and human health questions,” Barrows said.

She said she wants people to have the information about how much plastic waste is out there in microscopic or nearly microscopic form and use it to inform their consumer and lifestyle choices. That might mean ceasing to buy water in plastic bottles, or it could mean wearing primarily clothing made from fibers that will naturally degrade, like cotton or wool. A group she works for, Adventure Scientists, is compiling data on microplastics around the world, and is sharing that with those who ask for it. The last thing she wants is to start a panic.

“I don’t want people to be scared of the ocean,” Barrows said. “I don’t want people to be like ‘I am never going to eat anything out of the sea.’ ”


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