TESTIMONY OF
JEFFREY M. REUTTER,
Ph.D., DIRECTOR
OHIO SEA GRANT COLLEGE
PROGRAM,
F.T. STONE LABORATORY,
CENTER FOR LAKE ERIE
AREA RESEARCH (CLEAR), AND
GREAT LAKES AQUATIC
ECOSYSTEM RESEARCH CONSORTIUM
THE OHIO STATE
UNIVERSITY
At a Field Hearing
before the
United States Senate
Committee on Environment and Public Works
Cleveland, Ohio
25 August 2003
“The Dead Zone in Lake
Erie: A Brief History, the Current
Status, and Recommendations for the Future”
My name is Jeffrey M. Reutter. I have been doing research on Lake Erie,
studying this wonderful resource, and teaching about it since 1971. I am the Director of the Ohio Sea Grant
College Program (part of NOAA), the F.T. Stone Laboratory (the oldest freshwater
biological field station in the country), the Center for Lake Erie Area
Research (CLEAR), and the Great Lakes Aquatic Ecosystem Research Consortium
(GLAERC). I have held these positions
since 1987. I am here today to speak to
you about the area of hypoxia or anoxia in the middle of Lake Erie, the
so-called “Dead Zone,” to discuss its history, the current status of the lake,
and to make a few recommendations for future action. To do this I need to tell you a little about all of the Great
Lakes, how Lake Erie differs from the other Great Lakes, and a little basic
limnology so you can understand the problem.
I will build on my testimony before this committee in July 2002 and
discuss current efforts and needs. We
have also developed a poster describing this problem with I will leave with Senator
Voinovich.
While this is a very complex issue, the
take-home message from my testimony is simple.
Due in part to changes brought about by invading species, zebra and
quagga mussels, reduced water levels, and global warming, I am concerned that
we are seeing indications that Lake Erie is heading back to the conditions of
the “dead lake” years in the 1960s and early 70s. We must determine if that assessment is accurate, and if
accurate, we must identify actions and management strategies to minimize the
damage. Finally, we must recognize
that the Central Basin of Lake Erie, because of its very unique morphometry, is
the best indicator in all of the Great Lakes of larger stresses and problems.
Solving these problems will require
coordination and collaboration on the research front, the management front, and
the outreach front. Consequently, I am
a strong supporter of recent funding from NOAA Sea Grant to the Great Lakes
Commission and the Northeast-Midwest Institute to develop a Great Lakes
Restoration Plan. I also strongly
support Senator Voinovich’s efforts to sponsor the Great Lakes Environmental
Restoration Act and an amendment to include the Great Lakes in the Harmful
Algal Bloom and Hypoxia Act. I have
also recently been appointed to the Steering Committee for the Global Ocean
Observing System (GOOS) and strongly encourage everyone to support the
development of an Integrated Ocean Observing System (IOOS) that includes the
Great Lakes. We need a string of
monitoring buoys around all of the Great Lakes.
The Great Lakes hold 20% of all the
freshwater in the world and 95% of the freshwater in the United States. The US shoreline of the lakes is longer than
the Atlantic Coast, Gulf Coast and Pacific Coast, if we leave out Alaska. Approximately 30% of the US population lives
around these lakes.
Lake Erie is the southernmost and shallowest
of the Great Lakes. As a result, it is
also the warmest. It also provides drinking
water to 11 million people each day.
The other Great Lakes are all in excess of 750 feet deep, and Lake
Superior is 1,333 feet deep. The
deepest point of Lake Erie is about 210 feet in the eastern basin, off Long
Point. As a result, Lake Erie is the
smallest of the lakes by volume, and Lake Superior is 20 times larger than Lake
Erie. The watersheds around the other
four Great Lakes are all dominated by forest ecosystems. The watershed around Lake Erie is the home
to 14 million people and is dominated by an agricultural and urban
ecosystem. As a result Lake Erie
receives more sediment and more nutrients than the other Great Lakes. Now, if Lake Erie is the southernmost,
shallowest, warmest, and most nutrient enriched of the lakes, we should expect
it to be the most productive of the Great Lakes. It is. In fact, we often
produce more fish for human consumption from Lake Erie than from the other four
lakes combined.
Lake Erie has gone from being the poster
child for pollution problems in this country to being one of the best examples
in the world of ecosystem recovery. A
little over 30 years ago, 1969, the Cuyahoga River burned and Lake Erie was
labeled a dead lake. Nothing could have
been further from the truth. In reality
the Lake was too alive. We had put too
many nutrients into the Lake from sewage and agricultural runoff. These nutrients had allowed too much algae
to grow, and that algae, when it died and sank to the bottom, had used up the
dissolved oxygen in the water as the algae was decomposed by bacteria. This sequence is a natural aging process in
lakes called eutrophication, but man had accelerated the process by 300 years
by putting in too much phosphorus. It
is very similar to what we are seeing today in the Gulf of Mexico, but the
problem in salt water is nitrogen.
Scientists divide Lake Erie into three basins
based on significant differences in shape and depth. The Western Basin is the area west of Sandusky and has an average
depth on only 24 feet. The Eastern
Basin is the area east of Erie, Pennsylvania and contains the deepest point in
the Lake. The Western and Eastern
Basins have irregular bottoms with a lot of variation in depth. The Central Basin is the large area between
Sandusky and Erie. The average depth of
this basin is about 60 feet and the bottom is quite flat. Unfortunately, it is this shape that causes
this basin to be the home of the Dead Zones.
Many of you have probably experienced
swimming in a pond and noticed that the deep water was much colder than the
surface water. This layering with warm
water on top because it is less dense and lighter, and cold water on the bottom
because it is heavier, is very common in the Great Lakes. The warm surface layer is called the epilimnion. The cold bottom layer is called the hypolimnion. The line of rapid temperature change between
the layers is called the thermocline.
In Lake Erie, these layers form in the late spring and break up in the
fall when the surface layer cools to the temperature of the bottom layer—normally
in September or October.
In Lake Erie, the thermocline usually forms
around 50 feet. Based on the depths of
the three basins, this means the Western Basin is too shallow to have a
thermocline except on rare occasions, the Eastern Basin will have a thermocline
and there will be a lot of water below it in the cold hypolimnion, and the
Central Basin will have a thermocline but there will be a very thin layer of
cold water under it in the hypolimnion.
At the time the thermocline forms, there is
plenty of dissolved oxygen in the hypolimnion.
However, due to its depth, there is often no way to add oxygen to the
water in the hypolimnion until the thermocline disappears in the fall. Therefore, throughout the summer the oxygen
that was present when the thermocline formed is used by organisms living in
this area, including bacteria, which are decomposing algae as it dies and sinks
to the bottom. If large amounts of
algae are dieing and sinking, then large amounts of oxygen will be required for
the decomposition process. It should
then seem logical that if we could reduce the amount of algae, we could reduce
the amount of oxygen that would be required to decompose the algae. It should also seem logical that if the
hypolimniom was thicker (if the lake was deeper) it would have a larger
reservoir of dissolved oxygen.
Because the Western Basin seldom has a
thermocline, this is not a problem there.
And, because the Eastern Basin is so deep, there is a large reservoir of
oxygen in the hypolimnion—enough to last through the summer until the
thermocline disappears in the fall. The
Central Basin, however, does not have a large reservoir of water or oxygen in
the hypolimnion because the basin is not deep enough. As a result, loss of all the oxygen, or hypoxia (levels below 2.0
ppm) or anoxia (no oxygen), can be a serious problem in the bottom waters of
the Central Basin. Areas of anoxia were
first observed as early as 1930, and by the 1960s and 1970s, as much as 90% or
the hypolimnion in the Central Basin was becoming anoxic each year. This is why Lake Erie was labeled a “dead
lake.” When an area becomes anoxic,
nothing but anaerobic bacteria can live there.
Also, this water creates severe taste and odor problems if it is drawn
in by water treatment plants servicing the population surrounding the Lake.
To reduce the amount of algae in the Lake, we
needed to reduce the amount of the limiting nutrient. By “limiting nutrient,” I mean the essential nutrient that is in
the shortest supply. Without this
nutrient algae cannot grow and reproduce.
In freshwater this nutrient is phosphorus. In 1969, we were loading about 29,000 metric tons of phosphorus
into Lake Erie each year. Our models
told us that in order to keep dissolved oxygen in the Central Basin, we needed
to reduce the annual loading of phosphorus to 11,000 metric tons. This was accomplished and the recovery of
the Lake has been truly remarkable. The
walleye harvest from the Ohio waters jumped from 112,000 in 1976 to 5 million
in 1988 and the value of this fishery exceeds the value of the lobster fishery
in the Gulf of Maine. Small businesses
associated with charter fishing increased from 34 in 1975 to about 900 today,
and Lake Erie became the “Walleye Capital of the World.”
Then on 15 October 1988, we documented the
first zebra mussel in Lake Erie.
Recognizing the significance of this discovery, Ohio Sea Grant initiated
a research project on 15 November to document the expansion of the mussels. One year later, the densities in the Western
Basin had reached 30,000 per square meter.
Their impact was so great that in 1993 I addressed the International
Joint Commission and asked them to create a special task force to try to
understand the huge changes that were occurring in Lake Erie. I was asked to be US Co-Chair of the Lake
Erie Task Force for the International Joint Commission from 1994-1997 as we
developed models to better understand the impact of the zebra mussel on the
ecosystem of the Lake.
In 1998 I formed the Phosphorus Group, a
group of about 50 scientists from the US and Canada to discuss phosphorus
levels to determine if they might have gotten too low and were harming the
fishery—at that point the walleye fishery had been reduced by about 60% and the
smelt population had been decimated.
This group concluded that based on changes in the system caused by zebra
mussels, adding more phosphorus would create more zebra mussels and more
inedible, blue-green algae.
At the end of 1998, Drs. Jan Ciborowski
(University of Windsor), Murray Charlton (National Water Research Institute of
Canada), Russ Kreis (US EPA) and I formed the Lake Erie at the Millennium
Program to continue to lead discussions and focus attention on the huge changes
that were occurring in Lake Erie. We
have documented a number of new invaders to the Lake, including the round goby,
and have observed the gradual transition from zebra mussels to quagga mussels,
a relative of the zebra mussel, but a species we know much less about.
In the mid-1990s, US EPA’s Great Lakes
National Program Office (GLNPO) observed an increase in phosphorus levels in
Lake Erie and the increasing trend has continued. They also observed areas of anoxia in the Central Basin that
showed indications of growth. In 1996
we observed a bloom of blue-green algae in the Western Basin—an indication that
phosphorus levels were high. In 2001 we
saw more indications that dissolved oxygen levels were critically low, and we
observed that mayfly larvae had been eradicated from several regions—a clear
indication that oxygen had been eliminated.
We also observed reduced water transparency over the artificial reefs we
had worked with the City of Cleveland to produce from old Brown’s
Stadium—another indication of an anoxic hypolimnion.
The above information was shared with the
GLNPO and they asked me to bring together a group of Lake Erie experts for a
meeting in their Chicago offices on 13 December 2001 to discuss the problems we
were observing in Lake Erie and strategize about solutions. As a result of this meeting, GLNPO issued a
call for research proposals in January 2002 and fund a one-year project lead by
Dr. Gerry Matisoff, Case Western Reserve University, and the four scientists
mentioned above from the Millennium Program, to attempt to better understand
the dissolved oxygen problem in Lake Erie.
This project included many scientists on both sides of the border and
results have been presented in May 2003 at the Millennium Conference and at
IAGLR.
GLNPO recently completed another science cruise
aboard the Lake Guardian from 14-19 August. Preliminary results from this cruise indicate that hypoxia was
evident at half of the stations and only 20% of the stations showed dissolved
oxygen levels about 4 ppm, the minimum level for most fish species. In June of this year, Ohio Sea Grant and
Stone Laboratory placed a monitoring instrument one foot above the bottom at a
station approximately seven miles north of Huron, Ohio in an area we call the
Sandusky Sub-basin. This instrument, a
YSI 6600, makes hourly readings of dissolved oxygen and five other
parameters. This site was chosen
because it is among the most productive sites in the entire lake and it was the
first area to exhibit anoxia as early as 1930.
This year hypoxia was first observed at this site on 4 August, and a low
value of 0.2 ppm was observed on 8 August.
Oxygen is not likely to return to these stations until the lake turns
over during a storm this fall when the upper warm layer cools to a temperature
almost equal to the cold bottom layer.
It is also important to note the Microcystis sp., a harmful form
of algae that produces the toxin microcystin, has been increasing in density in
the Western Basin for the past two weeks and is nearing bloom levels.
I believe the oxygen problem is real and that
it is growing. There are clearly a
number of exacerbating conditions that are causing this. It now appears clear that Lake Erie has been
gradually warming for the past 100 years, that phosphorus concentrations having
been increasing since 1995, and that the water level has fallen sharply since
1997. Together, these conditions reduce
the amount of oxygen available in the hypolimnion of the Central Basin and
accelerate the use of the oxygen that is available. It also appears likely that zebra mussels and quagga mussels are
exacerbating the problem by releasing phosphorus and allowing it to cycle more
frequently through the system.
Needs:
·
Reduce the
amount of phosphorus entering Lake Erie—difficult, but possible.
·
Eliminate zebra
and quagga mussels—difficult and probably not possible.
·
Eliminate
global warming—difficult and most people don’t even realize it is a very
serious problem.
·
Increase the
water level of Lake Erie—currently Mother Nature holds all of the cards and models
of how global warming will affect this indicate that levels are likely to go
down.
The dead zone problem in the Central Basin of
Lake Erie should be a wake-up call for all of us. The ecosystem in the Great Lakes cannot be taken for
granted. We badly need a huge influx of
federal funding on the scale of that used for the Florida Everglades to address
the recovery of the Great Lakes Ecosystem from the dissolved oxygen problems to
contaminated sediment and harmful algal blooms. We should all support Senator Voinovich’s efforts to sponsor the
Great Lakes Environmental Restoration Act and an amendment to include the Great
Lakes in the Harmful Algal Bloom and Hypoxia Act. The Senator has lead efforts in the past to improve sewage
treatment capabilities. We must get
behind him again to eliminate combined sewers and problems like those that
occurred here in Cleveland at the sewage treatment plants during the 14 August
blackout.
We badly need a coordinated plan that
includes and coordinates that activities of all agencies. Some of us will be leaders and some of us
must accept roles as team players.
Currently, there are too many cooks in the kitchen when it comes to
managing the Great Lakes Ecosystem. We
need better coordination. We should all
support the recent funding from NOAA Sea Grant to the Great Lakes Commission
and the Northeast-Midwest Institute to develop a Great Lakes Restoration Plan.
Finally, I have also recently been appointed
to the Steering Committee for the Global Ocean Observing System (GOOS) and
strongly encourage everyone to support the development of an Integrated Ocean
Observing System (IOOS) that includes the Great Lakes. We need a string of monitoring buoys around
all of the Great Lakes so we are never caught off guard.