Tiny lake creatures
are falling victim to strange lesions
Cleveland Plain Dealer
that resemble tumors are appearing on the shells of flea-sized
crustaceans in the Great Lakes, and scientists now fear
an unknown pestilence is attacking a crucial link in the
freshwater food chain.
lesions are fatal to the tiny creatures known as zooplankton,
which are the primary food source for young salmon, yellow
perch, walleye and trout.
A National Oceanographic
and Atmospheric Administration report that summarizes
existing knowledge about the mysterious ailment calls
it "a serious, emerging threat to the food web."
The largest of
the zooplankton are one-eighth of an inch long. Somehow,
the small creatures' muscles, guts or gonads get outside
their shells, growing externally. One scientist studying
the phenomena said it looks as if "internal tissue tends
to leak out of the animal. When you have a lot of tissue
leaking out, you're dead."
of the lesions has quickly appeared, then disappeared,
from sampling locations across all five Great Lakes. There
is concern that shoreline tourism and fishing economies
may be devastated if the zooplankton supply collapses.
There is no evidence that the phenomenon has any adverse
effects on humans.
for three years have been tracking the slow spread of
the strange protrusions that were first discovered on
Lake Michigan zooplankton. As yet, they have not been
able to pinpoint the perpetrator.
summer, a U.S. EPA research vessel, the 180-foot Lake
Guardian, will be cruising the lakes collecting samples
To capture plankton,
the ship drags cones of white cloth that are up to 10
feet long. The Lake Guardian will spend several days in
Lake Erie this month, and is expected to visit Cleveland
found that predatory species of zooplankton - those that
eat other animals - are more likely to have the growths
than those eating vegetation. The abnormal growths are
more common near the shore than off shore.
"On a human,
it would look like a beach ball-sized hump growing out
of their body," said Tom Bridgeman, an aquatic biologist
at the Lake Erie Center, an Ohio research laboratory at
Maumee Bay State Park in the Toledo suburb of Oregon.
"When you see
it, it's hard to imagine that a plankton could even live
with these things attached."
not sure if the mysterious outbreak is a type of cancer,
an unknown infectious disease, a previously unseen parasite
or a reaction to years of industrial pollution. Nor can
they forecast how severe the threat may be.
studying the problem worry it could be a rogue pest that
hitchhiked into the Great Lakes in the ballast water of
an oceangoing freighter, the same route taken by zebra
mussels in the 1980s.
are that the tumor-like lesions could be related to the
start of global climate changes that may be affecting
In recent years,
ice sheets have not covered the Great Lakes because of
holds that the abnormal growths may be brought about by
extra sunlight streaming into lake water. Just a decade
ago, the water was murky and sunlight did not penetrate
very far into the depths. But that was before zebra mussels
dramatically altered the marine environment by filtering
and clarifying the Great Lakes.
"There are plenty
of theories, no answers," said Henry A. Vanderploeg, a
frustrated research ecologist at NOAA's Great Lakes Environmental
Research Laboratory in Ann Arbor, Mich.
"We all see these
tumor-like growths and lesions, but nobody knows what's
causing them. It's sort of a scientific nightmare."
he doesn't like to discuss the tumor-like growths.
"It could be
serious, but until we know what the heck is going on,
I'm reluctant to speculate."
a pathologist at an NOAA lab in Maryland, said she has
been studying the growths and does not believe they are
"If we could
find out what it is, we could determine if there's a new
organism out there invading the waters," Messick said.
"At this point, I can't really say how it got there, or
whether it has been there before, or whether it's come
in by shipping."
growths were found on plankton collected at a few sampling
sites in Lake Michigan. By last fall, their existence
was confirmed in Lake Erie and Lake Ontario.
Ohio researcher, said the culprit causing the growths
could be a microscopic parasite. He said the parasites,
which he found in an inland lake near Ann Arbor, Mich.,
20 months ago, puncture the zooplankton shells and absorb
the bodily fluids.
cleaning up the lakes may have freed up the parasites
to go on the attack. "Our lakes have been polluted so
long, it's possible the pollution acted like a barrier,"
the NOAA scientist, said the problem is not parasites.
"I have found
parasites on some of them, but the presence of parasites
is pretty low, less than 10 percent," she said. "The others
. . . well, we just don't know. But it's not parasites."
a fisheries researcher at the University of Michigan's
Center for Great Lakes and Aquatic Sciences, said research
at his lab has led scientists to believe the growths are
actual tumors. He disagrees with the Bridgeman's parasite
Institution sent samples that were collected in Lake Superior
in the 1880s. They had parasites. This is a different
abnormal growth," Omair said. "Is it a bug? A chemical?
I don't know. All I know is that it's a reaction to something.
This is a wake-up call that we have an unknown problem
in the Great Lakes."
A NOAA research
publication seems to agree.
mysterious culprit is, it must be like something right
out of a Stephen King novel for these tiny, shrimp-like
creatures. Just imagine waking up one morning to find
that something had burrowed a hole through your skin,
causing your innards to balloon out into a cyst the size
of your head."
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