To the naked eye, the waters of Tampa Bay look clean and inviting. But a new study says the bay, Florida’s largest estuary, is awash in tiny bits of plastic.
The study, published Thursday in the scientific journal Marine Pollution Bulletin, found about four billion particles of microplastics in the bay. Microplastics are each a 1/8 of an inch or smaller — tiny fragments of plastic bags or bottles, or threads from polyester clothing, discarded fishing line and other artificially manufactured jetsam.
Next up: a study that looks at how those bits of microplastics might be affecting manatees and other marine creatures that make their homes in the bay, according to Kinsley McEachern, the University of South Florida St. Petersburg marine sciences graduate student who led the study.
“Harmful chemicals and toxic organic pollutants like pesticides stick to them,” she said. And because the chemicals on microplastics can mimic hormones, "they can cause reproduction difficulties. It could have impacts throughout the entire food chain.”
So far, she said, there have been no studies on the impact on humans.
This is the first study to try to gauge just how badly polluted the bay has become from microplastics. McEachern got the idea for it several years ago when she heard Eckerd College professor David Hastings talking about his discovery that microplastics were turning up in samples his students were taking throughout the bay.
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McEachern wanted to quantify how widespread the pollution problem was, something that has never been done before in Tampa Bay.
Using a grant from the Tampa Bay Estuary Program and boats provided by the Hillsborough County Environmental Protection Commission, she and other biologists spent 14 months checking 24 different sampling spots around the bay.
The samples went through chemical and other tests to verify that what they were seeing under their microscopes was indeed plastic.
“We found the distribution was pretty ubiquitous,” she said.
The study found an average of four pieces of microplastic per gallon of water at all sites, and more than 600 pieces of microplastic per pound of dry sediment around the bay.
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Hastings praised McEachern’s study for taking a look at the pollution problem in three dimensions rather than just skimming the bay’s surface as studies in some other places have done.
The microplastics cascade into the bay from stormwater and, in the case of fabrics, from the washing machines that feed into municipal sewer treatment plants that eventually dump into the bay.
One possible source for microplastics that would be unique to Tampa Bay: the beads given out at the Gasparilla parade. During Keep Tampa Bay Beautiful’s Gasparilla cleanup day in 2015, volunteers collected more than 1,600 strands of discarded plastic beads.
RELATED STORY: Discarded beads not good for Tampa Bay.
The bits of plastic are of a size similar to plankton. Oysters, clams and mussels in the bay filter seawater to consume tiny bits of food, and thus wind up collecting the microplastics too, which then begin being passed through the food chain.
Biologists have been raising concerns about microplastics because they have been found in every ocean in the world, including the Arctic. The bits of plastic can collect and even concentrate toxins that can sicken any marine life that consumes the material. A 2010 study by Tokyo University and the Woods Hole Oceanographic Institution tested plastic pieces from 140 beaches in 40 countries. Researchers found chemical toxins in every sample.
For now, the only solution to this pollution problem is prevention, Hastings said. He encourages people to cut back on using throwaway plastic items.
“Something you use for 30 seconds could cause consequences that last a lifetime,” McEachern agreed.