From the Carteret News-Times (Morehead City)
29 July 1998
First big fish kill of summer reported in Neuse River
By Brad Rich
Staff Writer
State scientists are trying to determine the cause of the summer's
first big fish kill in the Neuse River.
Approximately 188,000 dead menhaden were counted floating on the
surface of the river Monday, north of Cherry Point Marine Corps
Air Station.
Menhaden are tiny, inedible fish used for industrial purposes
because of their high oil content.
``The majority of the fish have Pfiesteria-like sores,'' said
Don Reuter, spokesman for the state Department of Environment
and Natural Resources (DENR), referring to the toxic, fish-killing
dinoflagellate that has plagued North Carolina and other East
Coast states in recent years.
``It's the first big fish kill of the summer.''
Officials said the kill area extended five miles by six miles,
straddling the Pamlico-Craven county line between Hancock Creek
and Kennel Beach, but Mr. Reuter said it wasn't like a ``carpet
of dead fish.''
He said the state's rapid-response team had a difficult time determining
the exact number of dead fish because of shifting winds that moved
the fish in different directions. A state Division of Marine Fisheries
plane also was in the air Monday checking the extent of the kill.
Dr. JoAnn Burkholder, a Pfiesteria expert from N.C. State University,
also is investigating the kill.
But Dr. Jay Pinckney, a researcher at the UNC Institute of Marine
Sciences in Morehead City, doubted that Pfiesteria was to blame
for the kill Monday.
He said low oxygen levels near the shore of the river were more
likely the prime cause.
Dr. Pinckney said he examined data from permanent water quality
monitoring stations set up in the river by the U.S. Geological
Survey. He found that for several days before the kill, several
stations reported anoxic (no oxygen) conditions in the bottom
third of the water column.
Then, he said, the monitors showed that the water level rose 2
feet in about two hours on Sunday.
Apparently southwest winds had pushed the water to one shore for
several days, and when those winds relaxed Sunday, that water
sloshed back over.
``What I think happened is that when the wind relaxed, the anoxic
water moved to the shallow area for a short time, long enough
to trap a school of menhaden and kill the fish,'' he said.
The next day, Monday, monitors indicated water in the area was
normal, Dr. Pinckney said, so investigators probably didn't find
unusual conditions when they went to the site that day.
``I'm not totally discounting that Pfiesteria caused it (the fish
kill), but there are low levels of Pfiesteria out there all the
time without fish kills happening,'' Dr. Pinckney said. ``I think
low oxygen was responsible.''
And, he added, it would be perfectly normal for an anoxic event
on Sunday to result in a fish kill that wasn't spotted until Monday.
Dr. Pinckney also pointed that Dr. Larry Crowder, a researcher
at the Duke University Marine Laboratory in Beaufort, was finding
menhaden with Pfiesteria-like sores in the Neuse several months
ago, even though state and federal fisheries researchers were
not finding any Pfiesteria in the water.
Menhaden appear to be particularly vulnerable to Pfiesteria, perhaps
because of their high oil content, but they also appear to be
more vulnerable to anoxic conditions than other fish.
Pfiesteria lies dormant, much like a plant, until it senses the
presence of fish, then emits a toxin that eats holes in the flesh
of fish.
Some experts contend the organism can cause health problems, such
as short-term memory loss and skin sores, in humans who encounter
in the water.
State studies have found no proof of that yet, but officials have
urged the public to avoid any waters where dead fish are seen.
Whatever the cause of the kill, state Health Director Dr. Dennis
McBride said that anyone who does come into contact with water
where there is a fish kill or fish that have sores should remove
the wet clothing and keep it separate from others items until
it is washed.
Any body parts exposed should be promptly washed, and a doctor
should be called if any symptoms arise that might have been caused
by the exposure.
Scientists have predicted more fish kills this summer, in part
because of runoffs of nutrients, primarily nitrogen, from lawns,
sewage treatment plants, farms and animal lots and paved surfaces
during heavy spring rains.
The nitrogen stimulates the growth of algae and other plants,
and when bacteria break down the plants, the process robs the
water of oxygen.
In addition, Pfiesteria outbreaks often occur in nitrogen-rich
water.
The state has proposed to reduce the nitrogen flow into the Neuse by 30 percent by limiting discharges from waste treatment plants and requiring vegetative buffers along the river and its major tributaries, but very little of the plan has gone into effect.