species named lakes’ top enemy Tom Henry
CLEVELAND - Lake Erie’s delicate biological health remains
spotty at best, and there’s little doubt now that it won’t
get much better until the massive problem with invasive
species is tackled.
The intruders were ranked as the lake’s worst enemy in a
U.S. Environmental Protection Agency assessment here yesterday
on the final day of the State of the Lakes Ecosystem Conference,
a biennial meeting of the minds among Great Lakes officials.
While researchers have studied the damaging effects of zebra
mussels and other invasive species for years, a consensus
seemed to have emerged that the problem is getting worse
for each of the five Great Lakes.
"Time is of the essence to prevent additional biological
degradation and to ensure that the biological integrity
of Lake Erie and the St. Clair River and the Detroit River
ecosystems improves," Dan O’Riordan, manager of the U.S.
EPA’s Lake Erie team, said.
The agency’s assessment of Lake Erie remains unchanged from
last year, when it was ranked as "mixed to mixed-deteriorating."
That’s defined as a combination of good and bad regions,
with anxiety that the lake’s overall health could start
"We’re not slipping yet, but we’re not making the progress
we want, either," Mr. O’Riordan said.
Invasive species were identified as Lake Erie’s top issue,
followed by habitat loss, excessive nutrients, and a need
to refine ways of collecting data.
Long-standing problems with industrial pollution - while
still a concern - have been addressed enough with regulations
at discharge points to encourage a shift in research focus,
Mr. O’Riordan said.
Zebra mussels drive up industry costs by clogging water
intakes and suffocating native freshwater clams. They are
blamed for massive depletion of diporeia, a tiny shrimp
that has been a source of food for fish.
They help algae grow by excreting phosphorus, a common fertilizer,
into the water. They are believed to be at least partly
responsible for the dead zone in Lake Erie’s central basin,
although scientists said the verdict’s still out on the
Yet the impact goes way beyond zebra mussels.
Thousands of fish and birds have been found dead along Lake
Erie shores the past four years, the victims of a botulism
problem that appears to be growing because of a type of
bacteria spread by round gobies, another invader. Most cases
occurred near Buffalo, Mr. O’Riordan said.
Gobies became a target of the scientific community years
ago, after it was learned they were providing a new passageway
for toxic chemicals to get into the human food chain. Sportfish
feed on gobies.
The latest focus has been on the Asian carp, which has invaded
the Mississippi River and is feared to be entering the Great
Lakes at Chicago. It’s a fish that grows to 50 pounds and
has been known to leap out of the water as boats approach
and strike people on board.
The ever-changing Great Lakes ecology has been in flux since
vampire-like sea lampreys started entering Lake Ontario
in the early 1800s and sucked the blood out of fish. Since
the 1830s, 146 species - 83 types of plants and 63 fish
and other creatures - have entered the system, often in
the ballast water of ships.
The adjustment period never ends: It’s only now that officials
claim they’re having some success restoring the valuable
lake trout population that the lamprey virtually wiped out.
"You can never go back to what you had, and the change is
irreversible," Rimi Kalinauskas, Environment Canada restorations
program coordinator, said.
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