Scientists and researchers say the more likely cause is low oxygen levels and acidic conditions
By FRANK CARINI/ecoRI News staff
NORTH KINGSTOWN, R.I. — Dan Briggs is afraid he’s losing his job. That explains his angry posts to social media this summer. His venting, however, isn’t doing anything to solve the problem, but at least his boss doesn’t mind.
For the past 20 years, the South Kingstown resident has run a one-man commercial operation that sells streamers — dug by hand, with help from a short rake — from tidal areas throughout Narragansett Bay. The soft-shell clams he’s digging up now — far fewer than he was a dozen years ago — often don’t look right, at least when it comes to the color of their shells. He stopped eating his own catch several years ago.
“I know this is bad advertising for my business, but I want the bay cleaned up,” said Briggs, who comes from a long line of quahoggers and diggers. “I just want a cleaner bay, a better protected bay, so I can keep my job and sell high-quality shellfish. But we don’t care about cleaning up spots; we just cover our asses and close them to shellfishing.”
ecoRI News recently spent a Saturday morning with the frustrated fisherman. We meet him at Bissel Cove, which, according to the Environmental Protection Agency, was an impaired waterbody in 2014, 2012 and 2010 when it came to shellfish consumption. Rhode Island’s 2014 list of impaired waters also noted that Bissel Cove didn't support the consumption of shellfish, because of the presence of fecal coliform.
Briggs took us to two spots that he said once supported plenty of steamers. Today, both locations — Fox Island, a short boat ride from the shore of Bissel Cove, and the western shore of Jamestown — are largely graveyards for bleached clam shells.
Our guide blames the discoloration of the shells — and his dying livelihood — on the amount of chlorine being used at wastewater treatment plants to kill pathogens. He doesn’t buy the argument that the ultraviolet systems used at these facilities to remove chlorine before the treated effluent is released into Narragansett Bay is adequately addressing the accumulation of this element in the Ocean State’s most important natural resource. His eyes, and years of shellfishing experience, tell him something is wrong.
“We can’t continue to treat the bay like everyone’s private leach field,” Briggs said. “We’re dumping too much chlorine into the bay.”
The use of chlorine is reducing the amount of bacteria in Narragansett Bay, but Briggs believes the buildup of this element is having unintended and overlooked consequences. “Do you want to eat a bleached-out white clam?” he asked.
Chlorine at concentrations to bleach shells would be toxic to bivalves, according to scientists and researchers ecoRI News contacted after our late-July visit with Briggs. It's doubtful, they said, that that much chlorine was being released into Narragansett Bay, because of dechlorination procedures being conducted at wastewater treatment facilities to comply with the Clean Water Act.
Michael Rice, Ph.D., professor of fisheries and aquaculture in the Department of Fisheries, Animal & Veterinary Science at the University of Rhode Island, said the bleaching phenomenon in many species of clams can be caused by acidic bottom conditions, mostly in coves, brought about by summer decomposition of organic material that builds up during colder months.
"Microbial decomposition converts the organic sediments to carbon dioxide that causes local areas of low pH (acidic conditions) that erode the outer layers of the shells leaving chalky white surfaces," he wrote in an e-mail to ecoRI News. "Quahogs coming out of Greenwich Cove look like this often. The bad side of this is that steamers are less tolerant of these types of conditions than the quahogs that have a thicker shell."
Marta Gomez-Chiarri, Ph.D., chairwoman of URI's Department of Fisheries, Animal & Veterinary Science, said biogeochemical reactions may lead to conditions in sediments that can lead to the bleaching of shells.
"Of course, these are all hypothesis, and I don’t know of anybody that has tested them rigorously or done any measurements in the field to check if chlorine is present in areas where the bleaching occurs," she wrote in an e-mail. "This is a great question for researchers, and something that fishermen (not only clam diggers, but also lobstermen) have been interested in having scientists study."
On the Jamestown shore, Briggs flipped a dozen or so spots, typically finding more dead shells than live steamers. On one flip, he counted 14 dead and just three alive. The shells of both featured a lot of white. He noted that the percentage of dead steamers to live ones is disturbing.
“There’s nothing but dead shell here,” Briggs said. “No babies tells me there’s nothing here. Something is killing them.”
Ribbon worms alone can’t be held responsible, but David Gregg, Ph.D., executive director of the Rhode Island Natural History Survey, said research shows steamers are being affected by green crabs.
On the banks of Fox Island a little later, nearly a dozen more flips with his short rake exposed an even bleaker picture. Briggs uncovered only a handful of live steamers, but plenty of whitewashed dead shells. He said the same picture exists in once-fertile spots around the Jamestown and Newport bridges and along Prudence Island.
“Chlorine is killing them,” Briggs said. “There must be other ways to treat our sewage than dump it in the bay. I’m not a scientist, but there must be a better way to collect and treat our sewage.”
Chlorine is widely used as a disinfectant for sewage treatment plant effluent and to treat combined sewer overflow discharges. Chlorine can cause environmental harm at low levels, and is especially harmful to organisms that live in water. It combines with inorganic material in water to form chloride salts, and with organic material in water to form chlorinated organic chemicals.
The impact of chlorine use in wastewater treatment facilities on shellfish health, however, is largely unknown, as little research has been conducted, anywhere.
"I’m sure chlorine in effluent does bad things but bleaching steamers white isn’t one of them," Gregg wrote in an e-mail.
He also noted that chalky shells "are more likely a symptom of ocean acidification caused by too much carbon dioxide in the air from burning fossil fuels." Gregg said he couldn't confirm that Narragansett Bay is more acidic now than before, but noted that chalky shells "is what I would think it could look like."
Briggs is one of the last remaining shellfishermen dry digging for steamers in Narragansett Bay tidal areas. His income dropped by $15,000 last year, despite working 300 days in 2015. A typical day means flipping some 200 square feet of coastline. He’s having a harder time filling his tall white buckets with steamers, which he currently sells for $4.50 a pound wholesale.
Briggs said state and local officials can’t just blame the disappearance of steamers — and other marine species — on overdigging or overfishing.
“We’re polluting the bay with chlorine and poop,” he said. “All the regulations, all the paperwork, are on us. We just can’t hide all this sludge in the bay. I love my job. That’s why I’m complaining.”