Toxins and mislabeling threaten NC seafood

Toxins and mislabeling threaten NC seafood


Editor’s note: This article is part 4 of 5 of the series Changing Tides, which was produced in part through the support of the Pulitzer Center.

Willy Phillips operates Full Circle Crab Co. and Seafood Market in Columbia in Tyrrell County, a wholesale and retail operation.

He’s observed a decline in water quality impacting the blue crab fishery. 

Blue crabs are a valuable commercial fishery in North Carolina, with a dockside value of more than $20 million in 2020. The Albemarle and Pamlico sounds are among the most productive crab fisheries on the East Coast.

Over the last several years, Phillips has observed “wild population swings that are unlike anything that we’ve seen in the past.”

“The sounds are the catch basins for all of the human detritus upstream and are causing a negative effect on (blue crab) populations,” Phillips said. 

“I’m very familiar with the heartbreak that comes from people investing their entire lives in the industry and watching it melt away underneath their feet through the lack of real attention from the rest of the population as to what’s occurring in our waters,” he said. 

“There’s a whole chemistry that, frankly, I’m not sure man is capable of understanding.” 

The well-being of North Carolina’s most productive fisheries is threatened by worsening water quality, according to marine biologists and ecologists.

The question may not only be whether one can catch a fish but whether the catch is edible. And if you decide to dine on seafood someone else caught, in a time of changing seas, are you sure about what you are really eating?

Science of water quality

Aquatic ecologist Hans Paerl, the Kenan Professor of Marine and Environmental Sciences at the UNC Institute of Marine Sciences, shares Phillips’ concern about the quality of water in the Albemarle Sound.

At the start of his career, in the 1980s, he studied harmful algal blooms that appeared in the Chowan River and Albemarle Sound. 

The blooms formed through a combination of environmental factors, among them the accumulation of nutrients, particularly nitrogen and phosphorus, in bodies of water.

Management strategies eliminated the blooms for decades until their return in the last several years.

“There is every reason to be concerned from a human use perspective,” Paerl said. “You cannot swim in waters impacted by them.”

Nor can the toxic substances produced by the blooms be safely ingested by humans.

“It turns out the toxins can last for weeks in a system and end up in the food web,” Pearl said. “There is a hypothetical by which crabs can ingest some of the toxins since they are nonselective eaters. This is one of the concerns.” 

Researchers are certain the substances are in the water but have yet to pinpoint the exact sources. Possibilities include concentrated agricultural operations in the watershed, faulty septic systems and chemical fertilizers.

Intensive timber harvesting for the production of wood pellets, a booming North Carolina commodity, is also a source of concern. Trees act as a buffer for sediment that carries nitrogen. Removing trees increases the discharge of sediment into the watershed.

The Albemarle Sound is also a lagunal system in which nutrients are cycled many times in the body of water before it’s flushed into the sea. 

Raman Bhardwaj / Carolina Public Press

While this dynamic helps make the sound such a productive fishery, its bountiful waters are a curse when it comes to the production of algal blooms.

Unfortunately, “we can’t change the weather,” Paerl said. “The only real knob we have to tweak is the amount of nutrients.”  

Pearl is collaborating with state officials to identify sources and develop more effective strategies to control the invasion of sediment and the amount of nutrients entering bodies of water.

Whatever the source, climate change compounds the accumulation of nitrogen into North Carolina’s waterways.

More extreme rainfall events and warming, Paerl said, fall “right into the playbook of algal blooms.”

David Eggleston, director of N.C. State University’s marine laboratory, also studies the impact of climate change on crabs. If there’s any animal that can adapt to climate change, Eggleston said, it’s probably a crab. 

“We’re talking about a very resilient animal in terms of the dynamics of an environment,” he said. “If they are getting low on food, they’ll start eating each other.”

Crabs can also adapt to decomposing algal blooms that suck away oxygen. Eggleston discovered that crabs develop a physiological tolerance to low-oxygen events. They also respond well to changes in salinity as the result of inland flooding, storms and sea-level rise.

However, how fast they can adapt to those changes remains unclear, he said. Sudden and rapid changes in oxygen levels and salinity may be too fast for the versatile crustaceans.

“It’s all about the speed at which these changes are taking place,” he said.

What’s for dinner?

Knowing precisely where the seafood at a local market is sourced may not fend off the changes of a warming climate, but according to UNC marine ecologist John Bruno, the knowledge will support local, sustainable fisheries. 

As a teenager working as a prep cook in West Palm Beach, Bruno recalled chopping “scallops” from stingray wings with a round cookie cutter.

Intentionally mislabeling seafood was, and still is, a common practice, he said. 

Recently, with the help of students, he launched a nonprofit organization called Real Seafood.

Its mission: to ensure that seafood labels in North Carolina are accurate. 

Bruno, whose expertise is the impact of climate change on marine ecosystems in the tropics, developed a seafood forensics class to teach the fundamentals of DNA bar coding. 

So far, his students have taken genetic samples of shrimp and red snapper from restaurants, seafood markets and grocery stores.

They’ve proved that the “locally caught” shrimp on the menu may not be what you ordered.

“Often, you don’t know what you are buying,” Bruno said. “There’s a good chance the shrimp was farmed in, say, Ecuador and packed in a cooler for a year or two in Quito. It may eventually make its way to a seafood restaurant at the beach where they put it in a pan and claim they caught it yesterday.”

The mislabeled catch may not only lack flavor but also projects a false sense of abundance, he said. That leads consumers to inadvertently support seafood from poorly managed fisheries.

The link between consumer choice and fisheries management is meaningful, Bruno said. Accurate labeling is a valid action to support sustainable North Carolina fisheries from Wanchese to Wilmington. 

However, the biggest shocks to the availability of seafood will likely be the rapidly changing ocean conditions caused by a warming climate.

That’s something a label may not easily fix.



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