TITLE: Bay's tidal pools could be ancient Pfiesteria habitat; Pollution may have triggered migration to deeper waters
BYLINE: Douglas M. Birch
CREDIT: SUN STAFF
EST. PAGES: 3
DATE: 10/10/97
DOCID: BSUN537735
SOURCE: The Baltimore Sun; BSUN
EDITION: FINAL; SECTION: METRO; PAGE: 1B
ORIGIN: ST. LEONARD
NOTES: SEE HARD COPY FOR MAP
(Copyright 1997 @ The Baltimore Sun Company)
ST. LEONARD -- Scientists at a small research laboratory
have tracked Pfiesteria to a tidal marsh near here, the type of
habitat where, they suspect, the microbe may have puttered along
placidly for millions of years before rising pollution helped
it thrive in deeper waters.
Over the past two summers, scientists at the Academy of Natural
Sciences' Estuarine Research Center have netted fish from a marsh
on the shore of the Patuxent River and placed the fish in tanks
in a basement lab. Twice they have arrived in the morning to find
the fish stunned, pockmarked by sores or floating dead in the
cloudy water.
Each time, the culprit was tentatively identified as Pfiesteria
piscicida, a single-celled organism that ambushes its prey with
powerful toxins.
That microorganism has been blamed in recent months for injuring
and killing fish in North Carolina, Virginia and Maryland's lower
Eastern Shore, and for causing memory loss and other ailments
among some people who work on the water.
Denise L. Breitburg, a fish ecologist and assistant curator
of the Calvert County center, pointed out that Pfiesteria-like
organisms seem to prefer shallow, still waters rich in nutrients
and jammed with fish. That describes perfectly some of the puddles
left behind when the tide pulls out of a marsh.
"The ecology of the organism is such that it seems like
these inter-tidal marshes are the ideal habitat for it,"
Breitburg said.
No Pfiesteria-related fish kills or suspicious illnesses
have been reported in the wild along the Patuxent River. But concern
remains. The Department of Natural Resources this week sent field
biologists to the Patuxent to take water and sediment samples,
as well as collect and examine fish for signs of Pfiesteria-related
lesions.
John R. Griffin, state secretary of natural resources, said
Tuesday that of 914 fish his staff pulled from the Patuxent in
mid-September, "Six of them seemed to have something like
a Pfiesteria lesion."
He said he considers the percentage of sick fish "negligible"
but that the state will continue to monitor the Patuxent until
the weather turns cold. "Either it's in a toxic form, but
at so low a level that it's not creating a problem with humans,
or it's in its nontoxic form," he said.
No symptoms
No one at the Estuarine Research Center has developed symptoms,
Breitburg said.
She said the organism might have typically lived in shallow,
still and nutrient-rich tidal ponds along the Chesapeake Bay.
As pollution raised nutrient levels and caused other changes in
the bay's tributaries, conditions could have ripened for explosive
blooms of the organism.
"Through migration or rainfall, they may be flushed
out into the river," Breitburg said. "And they may thrive
in the river if nutrients are high and there are really high fish
densities. That could be a likely scenario.
"This is just a hypothesis, but I think this is a real
intriguing possibility."
Breitburg and her colleagues hope to use the marsh as a natural
laboratory for the study of Pfiesteria's life cycle in the wild.
They tracked the microbe to the marsh last month, when Jeff Smallwood, a 25-year-old staff scientist with the research center, pulled on hip waders and stomped through the pungent muck of a creek through the marsh, which is about a mile west of the research center.
Hunting amid the marsh grass at low tide, he found a puddle
of brackish water that seemed different from the rest: It contained
a few tiny fish and was covered with a thin milk-white froth.
"The water just looked funny enough there that I decided
to take some water samples," Smallwood said. He sent the
samples to JoAnn Burkholder, one of the scientists who discovered
and named the microbe. Her lab at North Carolina State University
confirmed that Pfiesteria was probably in the water.
"Jeff was incredibly observant," said Richard
V. Lacouture, a phytoplankton specialist at the research center
who has studied Pfiesteria for several years.
He pointed out that the organism, which has 24 life stages,
is difficult to identify except when it briefly assumes one of
several fish-killing forms. Burkholder's lab couldn't find Pfiesteria
in a water sample Smallwood took from another puddle, which contained
no fish, or in other samples that Department of Natural Resources
workers had taken from the marsh.
Breitburg's first encounter with the microbe, a member of
a class of marine organisms known as dinoflagellates, came three
years ago, when the Estuarine Research Center was in Benedict,
on the western shore of the Patuxent River in Charles County.
Breitburg scooped live fish off the end of a dock of an old
oyster cannery in late 1993, planning to use them for an experiment.
She wanted to determine whether she could trick fish into spawning
by mimicking summer conditions in the lab by artificially raising
the water temperature and lengthening the period of light.
The experiment fell apart in April 1994, when the fish began to die.
"I was sort of horrified that several months worth of
work had gone down the drain," she said.
Pfiesteria confirmed
Burkholder's lab confirmed Breitburg's suspicions: The culprit
was Pfiesteria in the water. Still, there was no way to know whether
the microbe came from the Patuxent. The tanks had been used to
keep fish from other regions and could have been contaminated.
Late in 1994, the Center for Estuarine Studies moved about
10 miles south and across the river, to the grounds of Jefferson-Patterson
Park and Museum in Calvert County.
The Pfiesteria incident was pretty much forgotten by the
summer of 1996, when Smallwood went to a marsh about a mile northwest
of the lab to collect small bait fish, called mummichogs, for
another of Breitburg's experiments. The fish were fine for three
days. Then the microbe struck.
"I came in in the morning and there was this pile of
dead fish there," Breitburg said.
Pfiesteria was present in the water, but again it wasn't clear where the organism had come from. The tanks hadn't been cleaned before they were filled with fish.
In August, Breitburg sent Smallwood to the marsh on two fish-collecting
expeditions. This time, she had cleaned the tanks and sterilized
the water with a filter and with ultraviolet light.
The first batch of fish stayed healthy, but the second -- about 200 of the quarter-inch-long mummichogs -- began thrashing and dying almost immediately after they were put into three tanks. About 40 percent of the fish died, many of them with lesions that stripped the flesh off near their tails.
Breitburg and Smallwood scrubbed down the cinder-block laboratory, using 10 bottles of bleach. She said they took the threat of health effects seriously enough to wear rubber gloves and to keep an eye on each other during the cleanup.
But they also joked about their close encounter with the organism, Breitburg said. When she sent an e-mail telling her colleagues of the fish kill, she recalled, "I told them, now we have more than the fact that we're over 40 and that we lived during the 1960s to blame our memory losses on."
Pub Date: 10/10/97
ART: COLOR PHOTO 1
COLOR PHOTO 2
MAP
PHOTO;
Caption: Search: Jeff Smallwood, a scientist at the Estuarine Research Center, near St. Leonard in Calvert County, uses a net to collect small fish from a tidal marsh where Pfiesteria has been found.
Ecologist: "The ecology of the organism is such that it seems like these inter-tidal marshes are the ideal habitat for it," says Denise Breitburg of the Estuarine Research Center. Pfiesteria's ancient habitat?
Scientist: Richard V. Lacouture, a phytoplankton specialist at the research center, says Pfiesteria is difficult to identify except when it briefly assumes one of several fish-killing forms.;
Credit: PERRY THORSVIK: SUN STAFF PHOTOS
PERRY THORSVIK: SUN STAFF PHOTOS
LAMONT W. HARVEY: SUN STAFF
PERRY THORSVIK: SUN STAFF
DESCRIPTORS: MARYLAND