The crabs and oysters we eat from the Indian River Lagoon harbor tiny bits of plastic, with unknown health risks to us and to them, new research suggests.
University of Central Florida researchers say our old fraying boat ropes, fishing equipment, fibers from synthetic clothes and other broken-down plastic bits are the source.
The so-called microplastics can harm oysters, crabs and other marine life, but long-term health and ecological effects remain uncertain.
“In general, microplastic fibers dominated in oyster and crab tissue,” Heidi R. Waite, wrote in a recent paper she submitted as part of her honors thesis at University of Central Florida.
Microplastics are bits of plastic less than 5 millimeters, the broken-down shards of our synthetic surroundings. Nylon and polypropylene fibers are among the most common. The itty-bitty plastics can build up in top predators like us, as well as birds and fishes. That magnifies metals, toxins and harmful additives associated with plastics.
“In almost every type of organism that people have studied they have found microplastic, generally – and sometimes fibers – typically in the guts,” said Maia McGuire, a SeaGrant extension agent in Bunnell.
In the Mosquito Lagoon, part of the Indian River Lagoon system, Waite found microplastic fibers, fragments and plastic beads in the water, oysters and crabs.
Water samples averaged 15 to 33 microplastic pieces per liter, more than three times what research in the northeastern Pacific Ocean and coastal British Columbia has found.
Crabs in Mosquito Lagoon averaged 23 microplastic pieces per crab, and oysters averaged 16 to 17 microplastic pieces.
“Although I expected to find microplastics in the organic tissues of the oysters, I was astounded by the quantity I found,” Waite said via email. “Compared to previous studies, this study revealed extremely high amount of microplastics in the organic tissues.”
Waite found crabs had higher overall concentrations of microplastic than oysters, but the majority get expelled.
The harm to marine life is unknown because the research topic is so new, biologists say, but some studies show toxic chemicals cling to plastics know to cause ill effects in humans.
Substances such as Bisphenol A and phthalates – which can cause cancer and endocrine disruption in humans – and other plasticizers used to increase flexibility, durability and transparency of plastics have shown up in whales and other marine life.
“They are something that lots of toxic chemicals will attach to,” said Linda Walters, a UCF biologist and Waite’s adviser. “If there are nasty molecules out there, there is a good chance they will find microplastic and attach to it.”
Researchers have documented more than 180 animal species that ingest microplastics, including sea turtles. In several species, plastics block the digestive system, damage organs and result in reduced feeding, growth rates and reproductive failure.
Microplastic has shown up in the circulatory systems of wildlife as well.
Plastics lodge in crab gills, decreasing their ability to respire.
Most oysters appear unaffected.
“The shellfish population are really hardy and really resilient, so this hasn’t been an obvious detriment,” Walters said.
But long-term effects remain uncertain. Lab research shows plastics harm reproduction and survival rates of shellfish. Fewer filter-feeding shellfish means dirtier water.
“The oysters are just going to keep accumulating microplastic. It never leaves,” Walters said.
Plastics can dupe birds, too, with deadly consequences.
“Their guts will just fill with plastic pieces they’ve eaten, so they think they’re full. They starve,” Walters said.
Boat ropes, fishing equipment, fleece and other synthetic clothing appear likely culprits, she said.
“That’s our best guess,” Walters said. “A lot of them were that royal blue color or yellow.”
Other research has found odd blue fibers floating in the lagoon. In 2015, Alexander Nickerson, a graduate student at Florida Institute of Technology, found similar fibers at five sites in the lagoon.
The most common particle was a lignin related to cotton, a biodegradable substance with no obvious threat to the lagoon, Nickerson wrote in his paper.
Since there are no cotton plants near the lagoon, the particles are from cotton textiles or cloth, or palms and other common local plants that resemble cotton lignin, Nickerson’s paper concludes.
Research shows cotton only remains in the water for about a month before decaying.
Microplastics from clothing fibers typically come from sewage and septic tank seepage of laundry water. The tiny fragments also form when plastics degrade in the elements. Rarely, they can come from personal care products such as body wash.
“It’s hard to point a finger at a single source as being the most to blame,” McGuire said.
Waite found fiber was the most common type of microplastic in oysters and beads the least common. Of those fibers, almost three-quarters were dark blue, suggesting they were from nylon and polypropylene boat ropes and/or clothing fibers.
Of the fragments found, about 88 percent were clear. Waite suspects those were plastics degraded from water bottles, packaging and other types of containers.
The density of microplastic pieces in water were relatively high compared to other estuaries worldwide, Waite notes. An estuary in China, for example, had 5 and 13 microplastic pieces per liter in water samples collected, about a third of what she found.
The higher concentration of microplastic in Mosquito Lagoon might be due to it having few openings to the ocean for tides to flush out pollution.
Plastics plague offshore waters as well. Florida researchers for years have found almost all of the baby sea turtles that wash up dead on Space Coast beaches have plastic in their stomachs, some with almost nothing but plastic.
The baby turtles eat the floating tar from ship fuels and plastic shards within weeks of being born, when they journey 25 to 45 miles offshore to feed in the Gulf Stream.
Shards of old milk bottles, bleach bottles and clear plastic bags are among the most common sources, state biologists say, some of it washing down the Mississippi from Missouri decades ago.
The problem could get worse. Plastic debris has drastically increased within the past few decades, accounting for 60 to 80 percent of marine debris, Waite’s paper notes.
In 1989, the Marine Plastic Pollution Research and Control Act made it illegal to dump plastic at sea and U.S. navigable waters. But the law is difficult to enforce, wildlife officials say.
Global production of plastics has grown from 1.7 million tons in the 1940s to 311 million tons by 2014 and is expected to double again in the next 20 years, according to the World Economic Forum.
That makes the plastics problem tough to crack, biologists warn.
“Our lives are plastic-based,” Walters said. “I don’t think you can tell people to stop using these types of fabrics, but cotton is better for these types of issues.”
She says people can help by not letting plastic float away and getting rid of boat lines when they start fraying, which can release hundreds of thousands of fiber fragments.
McGuire says to avoid products with synthetic fiber, until science unlocks more answers about health and environmental risks.
“It’s a 10,000-piece jigsaw puzzle, and we have 10 of the pieces and they’re not connected,” she said.