Years of hard work and millions of dollars went into cleaning up the nutrient pollution that was ruining Tampa Bay with fish kills and algae blooms. Now healthy sea grass beds are spreading across the bay bottom once more, and fish and manatees are swimming through water that has become clearer.
But in the meantime another pollutant, one that few people have ever heard of, has been building up in the bay and posing a serious threat to marine life in Florida's largest estuary. So far, nobody knows what to do about it.
Scientists are discovering "microplastics" — tiny shreds or particles of plastic — in every ocean in the world, including the Arctic.
Microplastics range from the decayed remains of monofilament fishing line to the microbeads that are now being used in some facial cleansers to unrecognizable debris that could come from any plastic product that has come apart.
Biologists have begun raising concerns about microplastics because they 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 such as PCBs in every sample.
Eckerd College marine science professor David Hastings regularly sends his undergraduate students out to take samples from Tampa Bay. Three years ago, after he began noticing microplastics in some samples, he told his students to specifically sample for them. Every spring they collected samples and then used a microscope to look for microplastics.
They hit the jackpot every time. Hastings said his crew has consistently found about 150 particles of microplastics in every gallon of water sampled. That amount is "high compared to the oceans," he said.
In their springtime sampling runs, they found the highest concentrations of microplastics in the center of the bay, where there's the least amount of water circulation, he said.
So far, they have done no research on where the pollution originated or what its effects might be, he said. Further studies are needed.
"Microplastics can change what type of bacteria are in sea water," said Koty Sharp, a microbiology professor at Eckerd. That can alter the most fundamental part of the aquatic food chain, she said. And if seabirds, fish and other marine creatures consume it, the microplastics may prevent them from absorbing what they need from the food they eat.
Hastings said he's unaware of testing being done for microplastics in any other Florida estuary. A national expert on the subject says the pollutant is probably in every one of them.
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"I suspect they can be found in virtually every coastal bay in the world that has a human population nearby using plastic products," said Woods Hole oceanography professor Erik Zettler, one of the authors of the 2010 study.
The Tampa Bay Estuary Program, a quasigovernmental group that has led the drive to clean up pollution in the bay, has not been tracking the microplastics problem. In fact, said program director Holly Greening, no one there was aware of Hastings' findings until a reporter called to ask about the subject.
Both Greening and Hastings said they think that at least some of the microplastics, particularly the facial cleanser beads, could be coming from the sewage plants that still dump treated waste into the bay — particularly the ones in Tampa and Clearwater.
Both have made great strides in preventing nitrogen from flowing into the bay from their waste stream, Greening said, but nobody has given any thought to screening out microplastics. Hastings said doing so "would be very, very difficult and expensive."
He said the microplastics are unlikely to show up in Tampa Bay's water supply, most of which still comes from the aquifer. Some drinking water is taken from the bay and run through filters at Tampa Bay Water's desalination plant in Apollo Beach. The filtering that removes salt would also screen out the microplastics, Hastings said.
Trying to clean up this latest pollution problem won't be easy. The first step, Hastings said, is cutting back on the use of so much plastic in our daily lives. He noted that Illinois, concerned about pollution, banned the use of plastic microbeads in facial cleansers this month, and that Ohio, New York and California are considering following suit. Canada and the Netherlands are also exploring bans.
"Today when I went to lunch I was served water in a plastic bottle. Twenty to 30 years ago that was not the norm. Instead, you'd get a glass and a pitcher," he said. "And I ate my lunch with a plastic fork. … What we need is an increased sensitivity to all the plastic that's around us in the environment."
It's wise to try to prevent that material from ever getting into the water, "because once the microplastics are in the water, I don't think there are any easy alternatives for getting it out."
Craig Pittman can be reached at firstname.lastname@example.org. Follow him on Twitter @craigtimes.