Month: August 2002

Back in the 1970’s, Lake Erie was considered dead. Too many nutrients were flowing into the lake, causing algae blooms that used up the oxygen. Massive fish kills were one result. Until recently, scientists thought they had the problem licked. But a few years ago, researchers began to realize those conditions were returning. Zebra mussels could be one culprit, but scientists aren’t sure. So the U-S EPA has launched a research ship to gather data that might help to unravel the mystery. The Great Lakes Radio Consortium’s Karen Schaefer reports:

Transcript

Back in the 1970’s, Lake Erie was considered dead. Too many
nutrients were flowing into the lake, causing algae blooms that used up
the oxygen. Massive fish kills were one result. Until recently, scientists
thought they had the problem licked. But a few years ago, researchers
began to realize those conditions were returning. Zebra mussels could
be one culprit, but scientists aren’t sure. So the U.S. EPA has launched a
research ship to gather data that might help to unravel the mystery. The
Great Lakes Radio Consortium’s Karen Schaefer reports:

For years, scientists believed the water quality of Lake Erie was steadily
improving, thanks in large part to a discovery made in the 1970’s. That’s
when researchers discovered that too much of the nutrient phosphorus was
making its way into the lake from farm fertilizers, sewage treatment plants,
and cleaning agents. The extra nutrients fed toxic blue-green algae blooms
that – in summer – often used up all the oxygen in the colder water at the
bottom of the lake, creating anoxic – or ‘dead’ – zones. New limits were
set on how much phosphorus could be discharged into Erie and other Great
Lakes and millions of dollars were spent to improve wastewater treatment
systems. By the 1990’s it was clear that efforts to reduce phosphorus loads
had been successful and until recently scientists believed that dead zones
were a thing of the past. But a few years ago, the U.S. Environmental
Protection Agency began to observe that levels of phosphorus were once again
rising, even though the same amount of the nutrient was entering the lake.

“And then in 1995, there was a big bloom of toxic blue-green algae
again. The increased phosphorus in the lake was a surprise and it
corresponds to the bloom of the blue-green algae.”

Dave Culver is a biologist with Ohio State University who’s been studying
Lake Erie since 1977. He says last summer a new dead zone appeared in the
lake’s central basin. In looking for the cause of the unexpected changes,
Culver and other researchers are turning their suspicions to Lake Erie’s
most recent immigrant – the zebra mussel.

“One of the possibilities is that zebra mussels are processing
organic matter and instead of allowing the phosphorus to settle out in the
sediments, they squirt it out their excurrent siphon up into the water
column where it can then used over and over and over again.”

Zebra mussels invaded the Great Lakes in the late 1980’s and spread rapidly.
But Culver believes zebra mussels may be just one of many possible sources
for the recent changes. He says it could be anything from farm run-off to
political policies.

“The questions is, given that we observe an increase, what are the
relative roles of external loading, internal recycling by zebra mussels,
changing water levels, global warming, a Republican governor… I don’t know
what all these things are.”

This summer Culver and some 30 other scientists from the U.S. and Canada
will be working to gather new data they hope will help solve the mystery.
It’s one of the biggest research investigations the U.S. EPA has launched in
the Great Lakes. The agency has brought in its research ship, the 180-foot
Lake Guardian. It’s equipped as a floating laboratory and scientists will
work and live on board, gathering samples of water, plankton and other
material from the lake’s Central Basin. On the back deck of the ship one
crew is working with Niagra University biologist Bill Edwards to program a
probe that will measure minute changes in water temperature.

“That’ll give us all kinds of information about what the transport
of things like the phosphorus and the oxygen and those things that the EPA
is very concerned about.”

What researchers find out this summer could have implications far beyond
Lake Erie. Zebra mussels are now well-established throughout the Great
Lakes. They’re also been found in the Mississippi and, most recently, in
the Tennessee River. Meredith Carr is a graduate student in engineering
studying fluid mechanics at the University of Illinois.

“One of the rivers we’re studying is the Illinois River of Lake Michigan, which
is another one of the Great Lakes. It serves as a source to
allow zebra mussel larva into the river, so understanding better what
happens in the lake, we can understand better what happens in the river.”

But finding out what’s happening in Lake Erie might not solve the problem.
If zebra mussels are the chief culprit, it might be difficult, even
impossible, to reduce manmade sources of phosphorus enough to restore a
healthy lake.

For the Great Lakes Radio Consortium, I’m Karen Schaefer.

Scientists are growing trees in a Northern Wisconsin forest – in a bath of greenhouse gasses. There’s a theory that forests can help limit the predicted increase in world temperatures from global warming… and its dire consequences. But early results suggest that Great Lakes forests might struggle to survive the century; doing little to help survival of the planet. The Great Lakes Radio Consortium’s Bob Kelleher has more:

Transcript

Scientists are growing trees in a Northern Wisconsin forest – in
a bath of greenhouse gasses. There’s a theory that forests can help limit
the predicted increase in world temperatures from global warming… and
its dire consequences. But early results suggest that Great Lakes forests
might struggle to survive the century; doing little to help survival of the
planet. The Great Lakes Radio Consortium’s Bob Kelleher has more:

On a research plantation near Rhinelander Wisconsin, some twelve thousand
trees are planted in wide rings. It’s called the Aspen FACE project …for
Free Air Carbon Dioxide Enrichment.

Some trees are growing in high concentrations of carbon dioxide .. a gas
that’s building in the world’s atmosphere, and considered a leading cause
of global warming. Others in elevated ozone … another global warming
pollutant closely associated with auto exhaust.

Dave Karnosky Directs the aspen FACE project from the Michigan
Technological University in Houghton, Michigan.

There’s still debate over carbon dioxide’s role in global warming. But
Karnosky says there’s no denying the upward trend in temperatures, and the
potential consequences.

“Things like glaciers melting on the North Pole, and sea level
increasing; violent storms, increased frequency of violent storms;
increased temperatures which will change the native range of plant
communities and forestry communities.”

There’s more than fifty studies underway here, from Institutions like the
Universities of Illinois and Wisconsin – even the Canadian Forest Service.

The main focus is to find whether forests might absorb significant amounts
of carbon. Holding carbon out of the atmosphere could help keep global
warming from spiraling out of control. If that’s the case, forests could
be used like a sponge to soak up CO2 generated by cars and industries.

But Karnosky’s a forestry expert. He wants to know how elevated carbon and
ozone might affect the region’s trees.

“Will these forests remain as productive in the future? Will
they be more productive, or less? So, we talk about these as being sort of
a window into the future. We like to think of our site as what the future
climate will be, say in the year 2050.”

The research site is eerily reminiscent of the ancient stonehenge ruins in
England.

Each ring is one hundred feet across. The trees are head high, surrounded
by a monument of pipes which rise straight up maybe ten feet higher, and
connect across the tops. A central computer directs high pressure jets of
gas.

Forest Service Biologist Mark Kubiske says early results are surprising.

Trees growing in a high concentration of carbon dioxide do well. Carbon
dioxide is to a plant what oxygen is to an animal. But CO2 isn’t the only
pollutant on the increase. There’s others, like ozone.

In the nearby computer shack, Kubiske says trees grown in ozone pollution
do poorly. Some aspen strains in ozone won’t make it ten years.

“The very sensitive clones are starting to drop out of the experiment; they’re dying
early. And the less sensitive clones are tending to take over the site. So, the effect
of the gasses on the composition of the forests that we’re investigating, is altering the way the different species and the different clones seem to interact.”

Combine ozone and carbon dioxide, and you find that any benefit trees get
from extra CO2 seems to be offset by the damaging effects of ozone.

(ambient sound)

Bill Mattson is a Forest Service entomologist. Mattson says trees grown in
ozone get attacked by insects and fungus at a much higher rate. They also suffer
from animals and birds.

“We’ve noticed that hares and rabbits, for example. They seem to
respond to the smaller plants in a community, and so they start attacking
smaller trees. You’ll see lots of woodpecker injury; lots of sapsucker
injury on those slower growing ozone trees.”

The ozone trees are riddled with small holes from wood boring beetles.

“So if you add those two chemicals together; it somehow is
enhancing the success of the beetles that bore into the stems of these
trees. That was something which I hadn’t expected.”

There’s evidence water moves differently through a tree under the gaseous
conditions. Some trees have elevated tannins in leaves but reductions in
other chemicals. That can have consequences on an ecosystem level, to the
animals and insects that feed on trees.

It might be hard to sustain forestry here in just fifty years. Aspen Face
is a relatively small, controlled experiment; but Mattson says the real
world is a giant experiment with no controls.

“It’s something to be watched very carefully, because we don’t know what the
ultimate consequences will be as we continue to ratchet up
ozone and CO2.”

There’s a dozen similar experiments worldwide. Each treats plants with CO2
and other predicted factors like high temperatures or drought. There’s more
than forestry at stake. There’s a real risk to world food production. If
forests can’t lock up carbon, there may have to be new restrictions on the
sources of carbon … the cars and industries burning fossil fuels.

For the Great Lakes Radio Consortium, I’m Bob Kelleher.