U.S. Water News Online
BOWLEYS QUARTERS, Md. -- The white perch and pumpkinseed
pulled from a state biologist's net in a tributary of the Middle
River looked healthy.
But the fish Rob Magnien observed here three years ago had serious
problems. A pfiesteria outbreak caused hundreds of menhaden -- a
small bait fish that swims in large schools -- to break out in ugly
open lesions, so large that in some cases the fishes' internal organs
hung out of their bodies.
``It would just turn your stomach,'' said Magnien, the Department
of Natural Resources' director of tidewater ecosystem assessment.
``You wouldn't believe the fish were still alive.''
The discovery on this heavily populated Baltimore County waterway
came two years after a toxic outbreak of the microorganism on the
lower Eastern Shore that caused more than a dozen people to get sick.
State officials monitored the Middle River nearly every day to see
if the pfiesteria turned toxic there, finally concluding that it did
In many ways, the effort to nail down what microscopic organisms
are in Maryland's waterways -- and what it means to the people and
wildlife that use them -- has not stopped since. DNR teams monitor
the water from April to October at about 70 sites on the Chesapeake
Bay and its tributaries, as well as a few places in the coastal bays.
A rapid response center was established on the Nanticoke River in
Dorchester County for collecting and processing water samples when
there's a fish kill. Other permanent monitoring stations are moored
to docks. The DNR has launched a Web site on which Marylanders can
check water conditions across the state.
Pfiesteria is still widely detected, though not in its toxic form.
Still, nontoxic pfiesteria can attack and feed on fish, scraping open
a wound that is exacerbated when fungus infects it, causing big,
bloody lesions. In the Middle River in 1999, the pfiesteria
population ``got so large that it seeded the entire river,'' Magnien
Since then, pfiesteria has lingered there, though water samples
indicate its presence has trailed off from about 50 percent last year
to 20 percent this year. That decrease pleased DNR biologists because
drought conditions this year are similar to those in 1997 and 1999.
However, August through October marks the peak season for
pfiesteria -- and DNR biologists note pfiesteria levels increased
recently on the Middle and Chicamicomico Rivers. Significant numbers
of menhaden turned up with lesions -- the first such instances this
Outbreaks like those in the late 1990s were a symptom of a larger,
ongoing problem that could cause future blooms of toxic pfiesteria
and other harmful microbes, Magnien says.
Scientists largely attribute the proliferation of algae in
Maryland's waterways to an overabundance of nutrients such as
nitrogen and phosphorus that are introduced by sources ranging from
sewage to coal burning industries in the Midwest.
Nutrients in Middle River are largely attributed to residential
and industrial wastewater. On the Eastern Shore, runoff of chicken
manure from poultry farms and fertilizers used for agriculture has
been widely blamed.
Even nontoxic algae can devastate the ecosystem. When it grows out
of control, it blacks out the light so that underwater bay grasses --
which provide crucial habitat for everything from blue crabs to small
fish -- can't grow.
Also, algae tends to grow in boom and bust cycles. When masses of
algae die at once, it consumes oxygen in the water -- which
suffocates fish. Large fish kills are often the product of an algae
boom that crashes.
``We need to address the nutrient problem, not just because of
pfiesteria but for the overall health of the system,'' said Theresa
Pierno, Maryland executive director of the Chesapeake Bay Foundation.
Two DNR boats hit the tributaries of the Middle River recently,
looking for signs of troublesome microbes in more than a dozen
locations. One boat surveys the fish, with biologists twirling
castnets into six feet of brackish water and studying the catch.
They document the size and health of all the fish, but they're
primarily looking for menhaden. There are no reliable chemical tests
for toxic outbreaks, so menhaden -- which are particularly sensitive
to infection -- serve as canaries in the coal mine.
The other boat focuses on the water, collecting a couple of liters
and sampling oxygen levels, acidity, salinity, temperature, clarity
and measurements of 14 different nutrients.
The samples are filtered in a portable lab in the back of a van.
Biologists add preservatives to the water, put it on ice, and ship it
to university and state labs for analysis.
First discovered in 1988, pfiesteria is a natural part of the
marine environment that is believed to have a highly complicated
lifecycle with 24 reported forms, a few of which can produce toxins.
Pfiesteria is a form of dinoflagellate, a microscopic, free-swimming,
single-celled organism that's usually classified as a type of algae.
Many dinoflagellates are plant-like, obtaining energy by
photosynthesis. But others, including pfiesteria, are more like
animals, acquiring some energy by eating other organisms.
There's still a lot that is unknown about pfiesteria -- including
what weather conditions help it thrive, why (some even question
whether) it morphs into a toxic state and how exactly it can affect
humans. Medical evidence collected in 1997 suggests exposure to an
active outbreak of pfiesteria may cause short-term memory
difficulties and respiratory problems.
Still, Magnien says there are species out there that may be just
``It seems that every year another species or two comes to
light,'' Magnien said.
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