State of the Coast Reports

1998 STATE OF THE COAST REPORT COASTAL FEATURE

     A startling new study offers the first evidence that the very basis of life in North Carolina's estuaries may be threatened for decades to come by heavy metals, DDT, and other chemicals.
     The contaminants may be killing the creatures that live in the mud at the bottom of the state's coastal tidal rivers and sounds, according to a recently released report by researchers at the University of North Carolina at Wilmington.
     The crustaceans and worms that live at the bottom of our coastal waters are the first link in the aquatic food chain, which also includes most species of fish, crabs and shrimp that support the state's multi-billion dollar commercial and recreational fishing industries. If the creatures in the mud go, so go the rest.

     That's why the results of this four-year study are so distressing. For years, there have been signs that our coastal waters are in trouble. But this study suggests that the trouble strikes deep, into the muds on which everything else rests, to the very core of the web of life.
     Courtney Hackney, a biologist and the leader of the UNC-W research team, has spent his career studying North Carolina's estuaries. All that time splashing around the water, though, didn't prepare him for what he found.
"We had been gathering data for four years, and I had not really looked at the data together," he said. "When we were putting together the report, I could not sleep at night. It was so disturbing."
     Hackney and his researchers collected sediment samples from 183 sites from Currituck Sound to the SC line. They analyzed the mud for 41 selected contaminants, looking for levels that are known to kill at least 10 percent of the organisms that live in sediment. They searched the samples for the creatures, noting their type and density, and they tested the mud's toxicity by exposing it to organisms that naturally live at the bottom of the state's estuaries. The researchers also collected fish and shellfish from the test sites, looking for sores, tumors or other evidence of diseases.
     The levels of at least one contaminant were high enough at 41 percent of the sites to be considered potentially toxic to mud-dwelling organisms. At an equal number of sites, the levels of individual contaminants weren't toxic, but the cumulative effect of multiple contaminants could kill the animals.
     Density of organisms that live in the mud was likely reduced at all contaminated sites. At the worst sites, the sediment was completely devoid of life. More than three-quarters of the samples from the most contaminated sites killed the test animals in the lab. Sediment from sites that were considered moderately contaminated killed the, test organisms more than half the time.
 Hackney would want it noted at this point that the same level of contaminants may not actually kill the same critters in the wild. Creatures behave differently in their natural environment than they do in a fish tank. The lab tests, though, provide a benchmark ... "a point of degradation," is the way Hackney puts it.

     Similar studies were done in other South Atlantic states as part of the Environmental Assessment and Monitoring Program in Estuaries, a federal effort to evaluate the health of the country's estuaries. No other Southern study turned up as many contaminated sites as North Carolina, Hackney said. The state's most contaminated areas, he said, may well rank among the worst on the East Coast.
     Chromium, DDT, PCBs, nickel, arsenic and mercury were the major contaminants that the researchers found in the muds. The most contaminated sediments, they noted, came from Albemarle Sound and from the Pamlico and Neuse rivers. Generally, the worst contamination came from areas of low salinity that were far from the inlets and thus least affected by the cleansing action of tides. They also receive a large amount of river discharge.
     Albemarle Sound fits that description perfectly. It is far from Oregon Inlet, the closest outlet to the ocean, and is fed by numerous rivers. So although they accounted for only 15 percent of the samples, the 28 sites in the sound produced all the mercury and lead contamination and 45 percent of the sites contaminated by PCBs. Almost all of the worst sediment samples killed test animals, and half of the fish collected at those sites had sores or other visible signs of disease.
     The Pamlico and Neuse rivers weren't much better. About half of the sites in the Pamlico were highly contaminated. Researchers tested sediment at sites that ran in a straight line for 10 miles down the middle of the river. As expected, the upstream sites were severely contaminated, but the contamination decreased steadily downstream.
     In the Neuse River almost three-quarters of the sites were contaminated with at least one contaminant, and 93 percent of the sites were considered highly contaminated based on all contaminants combined.
     "We don't have it all tied down yet, but we know that the contaminants are there;" Hackney said. "There are, for instance, whole areas in the Neuse and Pamlico where almost nothing lives in the bottom."
     Testing the top two centimeters of sediment assured researchers that they weren't looking at contamination caused by one or two recent spills. Much of the sediment, Hackney explained, was laid down during the last 50 years. DDT was banned more than 30 years ago, but it still shows up in river and sound muds.

Studied Contaminates

Trace Metals:
Antimony • Arsenic • Cadmium • Chromium • Copper
Lead • Mercury • Nickel • Silver • Tin • Zinc

Pesticides:
DDT • DDD • DDE • Lindane • Chlordane
Heptachlor • Dieldrin • Aldrin • Endrin • Mirex

PAH's
(polynuclear aromatic hydrocarbons):
Acenanapthene • Anthracene
Benzo(a)anthracene • Benzo(e)pyrene
Bipheny • Dibenz(a,h)anthracene
2,6-dimethylnapthalene • Fluorene
1-methylnapthalene • 2-methylnapthalene
Nepthalene • Perylene • Phenanthrene
Pyrene • 2,3,4-trimethylnephthalene

     "That just says that a lot of the stuff out there has been put in the environment years ago," Hackney said. ""If we cleaned it up tomorrow and stopped putting these things in the water, we would see this stuff for years."
     The report does offer a few rays of hope. Sediments in Pamlico Sound and the smaller estuaries along the state's southern coast are relatively free of the contaminants Hackney and his crew were looking for. All those areas aren't near a major river, which carries the contaminants, and are flushed daily by tides.
     Some test sites improved in 1996 because of the scouring and flushing action of two hurricanes. Before raising a cheer, Hackney would like to know where the contaminants went. Were they blown out to sea or did they just settle into an adjacent marsh?
     Sample sites were randomly selected and so do not help detect the source of the contamination. Those answers will have to await further studies.
     What Hackney has learned so far is enough to come to a simple conclusion. "The story is," he said, "we have a major problem."

For more information or a copy of the report email
hackney@uncwil.edu.