Scientists study 'dead zone' in
WINDSOR - Falling water levels and the introduction of
alien species may be slowing efforts to clean up Lake
Erie, scientists say.
Falling water levels, alien species slow efforts to revive
After many years and millions of dollars spent on cleanup
efforts, Lake Erie was considered to be in a state of
recovery. At one time, fish from the Detroit River were
filled with PCBs and covered in tumours.
"I hear they say they're no good to eat but I don't
see anything wrong with them," said Ben Sargiss as
he cast his fishing line into the river.
FROM AUGUST 6, 2002 Scientists investigate toxin, mussel
threats in Lake Erie
The fish are now considered safe enough to eat in small
amounts, but scientists are wondering about "dead
zones" in the deepest part of the lake.
Dead zones are oxygen-deprived areas where fish can't
survive. University of Windsor biology Prof. Jan Ciborowski
is leading the Third Biennial Conference of the Lake Erie
Millennium Network, where scientists are discussing the
Ciborowski said although the dead zone is centred in
the middle of the lake, the area can move.
"If you poured some water into a jar of oil, it
would form a bubble at the bottom," said Ciborowski.
"If you tilted the jar it would roll back and forth.
So where's the dead zone, where's that bubble? Sometimes
it's over there, and every time the wind blows the location
Research presented at the conference is helping scientists
understand if dead zones are natural or caused by human
activity. He said they are tracking elements such as a
warming climate but it's too soon to tell.
FROM JAN. 4, 2002 Water levels in Great Lakes hit new
Studies show warmer layers of water near the surface cut
off the oxygen supply near the bottom of the lake. As
water levels fall, the lake becomes warmer, creating the
potential for a larger dead zone, scientists say.
Gail Krantzberg is with the International Joint Commission,
which monitors the Great Lakes Water Quality Agreement
between Canada and the United States.
Krantzberg said part of the problem may be the introduction
of alien species like zebra mussels from ship ballast
"It is among the greatest threats to the health
and integrity of the Great Lakes, and the push can come
from the IJC but the muscle has to come from governments."
Krantzberg said while the cause of the dead zones remains
a mystery, enough is known about other threats to the
health of the Great Lakes that governments should take
more aggressive action.