cc
science for a number of years. >> I've been doing aquatic
we get opportunities to speak Ato the public and oftene,
the attendance is fairly low. But I have discovered over the
last year or so, that if you
like stinky algae, you do get much better attendance
for your talk.
And it's gratifying. ( laughter )
to speak. The title of the talk is,n
"Nuisance Algae in Lake Michigan,
and What Makes It Grow."
for the title is what makes it What you'd probably rather see
one of our objectives. not grow, because that's really
what makes the nuisance algae Butgrow in Lake Michigan,ing
we can also get at the issue
reduce that growth and make othe problem a little bito
more tolerable. ( inaudible )
Can everyone hear me okay?
As most of you know, there's Is this volume okay?
with Cladophora. a number of problems associated
are aware of is the aesthetic The one problem.t people
Here's an example here, closer
and once it starts rotting, to Milit smells terrible.rrible
There's other problems
It can clog water intakes, associated with it as well.
here on Lake Michigan and other parts of the Great Lakes haveh
actually had to be shut down
water intakes clogged becawith Cladophora.eir
And we're also starting to see
It's been in Lake Erie botulism in the Great Lakes.
It's starting to become a problem in some parts.
of Lake Michigan now. We're not sure, but
the hypothesis is that it's ultimately linked to Cladophora,
which can promote anoxic
which promotes the production cof the botulism bacteria.,
And it's also a nuisance
tends to get snagged up. when you go dive, because stuff
a number of years ago at the When we started looking
well, let's look at what Cladophora problem, we said,
look at the history of those Cladophora needs to grow, and
if we can figure out what enhas changed over the lastee
10-15 years that may be causing the excess Cladophora
that we're seeing now.
Cladophora needs to grow, it needs a hard substrate.
And on this side of the lake in Wisconsin, we're either blessed
or cursed, whichever way you
rocky bottoms. want to look at it, with lots of
doesn't have nearly as much, The Michigan side of the lake
nearly as big a problem there. and therefore Cladophora isn't
And in Lake Michigan, there's excess of all nutrients
except phosphorous. Phosphorous is at very low
concentrations in Lake Michigan,
controls the growth of most soalgae in Lake Michigan.at
And like for any plant, you need light.
Then the optimum temperature, which for the Cladophora is in
the 13-17 degrees Celsius range.
by looking at these factors in Lake Michigan, and how they
currently control Cladophora, and how they may have changed
in the past.
what are the roles of nutrients, So two key questions that are,
controlling Cladophora growth; light and temperature in
in the last 10-15 years in a way and how have those changed
increase that we're now seeing. And the way we did this, was
we did research both in the lake
In the lake, we did a lot of and in the laboratory.
light, temperature, nutrients, monitoring of those conditions,
itself, to see how Cladophora and nutrient status andphora
Cladophora growth changed in time
in relation to these variables. And one thing we were trying
to do is to develop a model that links Cladophora growth
to those variables
and light and temperature. of phosphorous loading,
of the model. Those three variables determine
the dissolved phosphorous concentration in the lake,
which then becomes stored phosphorous within
the Cladophora algae itself.
and temperature ultimately And that, combined with light
the biomass of the Cladophora determin the lake.th and
Now this is a model that
developed for Lake Huron a professor at Michigan Tech
Cladophora was a problem there. We're taking that model now,
and trying to make it work
with that professor who's still at Michigan Tech.
One difference is that when this difference was first
developed, there were no mussels
And now we have lots of mussels. in the Great Lakes.
model, because they Aare a source of phosphorous.s
Mussels eat the plankton, and then they excrete the
phosphorous, which in turn
for Cladophora. Mussels and Cladophora
live in the same habitat, in the near shore area,
on the hard, rocky bottom.
to each other. So they live in close proximity
is incorporate this into the So what we're trying to do now
are also potentially influencing model to see how mussels
in the lake. Cladophora production
of a model. This is the front face
of the model. There's a number of places where
you provide input to the model, temperature, light, dissolved
nutrients, and so forth.
of the model, where you provide Ana few variables here.ont
And then you can run the model, and it provides graphic output
here. And you may have trouble reading
this from the back. But this is the key graph
we like to focus on.
and this is --. This is running right nowa
from around early June, up until late September
or October. These points you see here
are actual measurements in the lake.
We go out into Lake Michigan. We measure the biomass
of Cladophora.
to what the model is telling us So should be out in the lakents
based on light, temperature and nutrients.
And you can see that, through this growth phase from May
until around the end of July, the model does fairly well.
There's not a lot here, but the general increment in Cladophora
is simulated fairly well
Later on in the summer, the model doesn't do so well.
This is what we call
The Cladophora's breaking off a slougnow. phase.
This is a problem time, when it's coming up on shore.
It's breaking off.
for that breaking off, because The model doesn't really account
the processes that cause we still don't really understand
But if you think about it from a management perspective
this is stuff that's
growing out in the lake. breaking off, because it's
we should be looking at this If we want to manage Cladophora,
stop the growth of Cladophora part in the first place.nt to
And in that growth phase, the model is doing fairly well.
So right now, at least for
calibrate the model, it seems to simulate growth pretty well,
so we can start using it to look at these different factors
and see how they control growth in the lake.
Well, first we look at
If we look at the history of temperature in the near shore
of Lake Michigan, this is what we've seen
over the last 35 years. This is just the June to August
average temperature,
There's a lot of noise in here. But in general, the temperature
has been increasing over the last several decades.
I won't go into all the details for why that's occurring now.
It's not so much global warming,
directions over Lake Michigan. as it is a change in wind
responsible for an increase Thof Cladophora in the lake.be
So if we use the model, and we put some different
temperatures in the model,
At 5 degrees, 10 degrees, 15 degrees Celsius, the model
is over a 200-day period
But at all those temperatures, and we see biomass increasing.
is roughly the same. the maximum biomass
warmer temperatures like 20 degrees and 25 degrees,
which is essentially
see biomass coming down. room temperature, we actually
warmer temperatures Cladophora And that's because at those
And it respires more than the photosynthesizing,
so it burns itself out. The Cladophora does best
at cooler temperatures, but we're seeing this shift
in Lake Michigan from an average
8 or 9 in the summer temperature of around
And what this is suggesting is that within that range,
that temperature change probably isn't causing a lot
of the change that we're seeing in Cladophora.
So we don't think, even though
we don't think that's playing tha big role in the Cladophora,
problem right now.
the history of light. Well, here's light at a depth
of nine meters in Lake Michigan.
This dashed lined here This is in the summer of 2006.
the threshold for Cladophora. If you're below that, Cladophora
has a tough time growing. If you're above that,
it's happy. And what we can see
at nine meters is that in July, you're border line.
As we get into August,
light for Cladophora September, we have sufficient
This is again at a depth, I think it's actually nine meters
where we had this light meter.
or a little bit deeper It can grow down to 10 meters,
If we look at the history of light in Lake Michigan.
This is the history of a disk that we put into the water
and you just drop it
And so the deeper the depth, till you can't see it anymore.
This is data collected the clearer the lake is.
And back in the early 1990, the disk depth was around
three meters. That's steadily increased
over the last decade and a half,
This trend has increased so that and this is going up to 2002.
three times as much as it was wback in the early 1990s.t
One reason is the mussels.
coming in in the early 1990s. Mussels are great filtering
machines. They pull all plankton
and particulate material
thereby clearing up the water. out of the water column,
than it used to be, thanks So the water is much clearer now
And now quagga mussels, which have largely replaced
zebra mussels.
This is just some water that Here's just an example of that.
I stuck it in two bottles. I took from Milwaukee harbor.
I let it sit for 30 minutes, In one, there are zebra mussels.
And you can see here this jar has cleared up a little bit,
but you can see how clear the water has gotten
in this jar.
just filter the all of that That'sstuff out of there.s here
And they're doing the same thing in the lake.
So if we back track, and
from the early 1990s we take that water clarity back
basically we take 2006 data, and plug it into,
in 1991 would have gotten anto the bottom of the lakeght
at nine meters. This is what we see.
Here's 2000,
This is 1991. In 1991, we would never have
had enough light at nine meters for Cladophora to grow.
But you do in 2004, because the lake has cleared up.
So it looks like light is potentially important factor
responsible for the increasing
What if we look at the third Cladophora that we've seen.
This is total phosphorous concentrations in Lake Michigan.
This is from the EPA monitoring program.
This is from 1983-2005. And a slow decline over time.
The target set for Lake Michigan
concentrations set by the Great Lakes Water Quality
Agreement is seven micrograms per meter.
And we're well below that now.
in Lake Michigan. So we've met the conditions of
that target, and yet we still have this Cladophora problem
near shore. If we look in the near shore
area, which is not the same as the offshore, here's
some data that I collected. I got it from MMSD, who has been
monitoring near shore around
What you see here is that Mit was actually declining near.
shore up until the '90s, but
there's been quite an increase in the last five to ten years,
of phosphorous. iThe near shore, at least now,ns
looks like it's a little bit
Quality Agreement. above that Great Lakes Water
offshore waters, but it looks Solike they're still exceededfor
at least some of the time for near shore waters.
So the question is, is that increase in phosphorous
in the near shore potentially contributing
to the Cladophora problem that we're seeing now.
Now we have this history
We know the temperature change of light.
And we have data on phosphorous change over time.
We can plug that data into
you earlier to determine that Cladophora model I showed
together to change Cladophora how thoseover time.tors work
So this is using conditions from pre-mussel era,
from the late 1980s, using
and light from that era. phosphorous, temperature
increased dissolved phosphorous ThenI've just showed you, this
and see what that would do
It raises this a little bit, to the Cladophora biomass.
What if we just take but not a lot.
so this is like 2006 the post-mussel water clarity,
into the model, but keep water clarity, and put that
as it was before the mussels. Now we see Cladophora abundance
really shooting up. So it looks like light is having
a much stronger influence than phosphorous alone.
When we put the two together, this is what we get.
So now we're getting three times
pre-mussels, due to this as much Cladophora as we were
water clarity and increased phosphorous concentrationr
in water. Now the next question is,
can we manage this? Can we do anything about this?
Well we can't do a lot about
willing to fly over the lake water clarity unless somebody's
dirt or something in the lake. every weekend and dump a lot of
a feasible option. It's not really
We can't do much Really, it's the only option.
The only option we have is to look at phosphorous.
And that's how the lake has been managed
for the last several decades. So if you go back to the model.
And what we want to do
to flat line. isWe'd like to see no increasee
in Cladophora over the summer.
in the model is that there is a phosphorous multiplier here.
And we can change that so that
that we provided and it takes all the input data
So it allows us just multiplied it by that number.
the phosphorous concentration and see what would happen
to the Cladophora biomass.
using real data for 2006. SWe can reduce that to .750,
to see what it does to Cladophora biomass.
What you see is that it starts
does continue to grow. to come down, but it still
a depth of nine meters, Nobecause that's where weat
collected most of our data for. Now if we reduce this to .5,
that's the point where, at least at nine meters,
we see biomass flat line. There's no growth or increase
in Cladophora over the summer,
for it to grow very much. becSo at nine meters, if welow
reduce phosphorous by 50%,
the growth of Cladophora we could pretty well stop
But you have to look at the whole near shore area.
Cladophora grows from close to shore to a depth
of about 11 and 12 meters.
that whole zone when we're And we have to consider
is going to respond thto changes in phosphorous.a
So here is a graph from two meters down to 10 meters,
of how Cladophora would change
in phosphorous. in responSo here's 100%ductions
of this 2006 data.
If we look just at our Here's 75%, 50% and 25%.
here's what we're calling the preferred Cladophora abundance.
Now this is not, we haven't put a lot of work into saying what's
the ideal Cladophora biomass. But this is a number the
Michigan Tech professor chose when he was doing work
on Lake Huron back in the 1980s.
He said 50 grams And so if we use that for now.
a nice target to shoot for. Well, at nine meters, if we
were to reduce phosphorous
we get down to that level. concentration by 50%,
even if you reduce by 50%, You can see at shallower depths,
that level. thIn other words, one thingve
to remember here about models.
who started at England and A famous statistician
UW Madison, he said all models actually finished his career at
some models are useful. The reason for that is
no mathematical model can ever really account for
the complexity
There's a lot of things going on out there that may influence
Cladophora growth, but we don't include them in the model,
because it's just too difficult to account for everything.
And so we have to be careful
to look into the future, or to when we use these models
And one example is looking at undthis depth distributionogy.
of Cladophora that is put out by the model.
In reality, we may see
Because as you get into shallower waters, there's more
wave action.
This Cladophora is broken off the rocks more frequently.
That doesn't happen out at these depths,
but it may at these depths. And some evidence for that
is a few years ago, we did
in the lake. depth profiles of Cladophora
which is close to our Here's a model depth. meters,
Here's five meters. The model says we should have a
lot more biomass at five meters.
It was almost the same But in fact, we didn't.
That's somewhat encouraging, as ten meters.
what I just showed you, maybe the results that we're seeing
here, as a result of phosphorous
see them at shallower depths, reductionas well. we also
But we have to do a bit more
how well this model will work wat shallower depths right now.
But that's just a precautionary note, that you always have to be
careful using these models. Nothing beats real data
from the environment. So now, we've looked at
some possible effects of reducing phosphorous.
If we want to reduce phosphorous
ask ourselves, in the lake, then we have to
Could we actually reduce where is it coming from?
in Lake Michigan. There's a few possible sources.
It may be coming from rivers, from the land being
washed into the lake. Or within the lake,
you've got the mussels. Mussels are eating particular
phosphorous in the form of
And a lot of that is excreted pout as dissolved phosphorous,.
which is the form that Cladophora needs.
Mussels also may be providing the phosphorous that's needed
for Cladophora growth.
take these rates for a certain So what we did was say, let's
Let's take the stretch between stretch of Lake Michigan.
let's look at the phosphorous Fox Pexcretion by mussels and
in that area. Let's look at the uptake
of phosphorous by Cladophora
balances. in tLet's also look atw it
the phosphorous input from
three numbers to see the river and compare those
Cladophora uptake, we estimated that around 119 milligrams
of phosphorous per square meter.
is around the same number. The river input
coming from the river to support Theoretically, there's enough
isn't 100% efficient. tIt's not going to graba
all of the phosphorous
A lot of it gets out into comithe open lake.ver.
We know that mussel excretion,
per square meter. This is the relative importance
of phosphorous flowing from the river to the near shore region.
And that importance changes as you move away from the river.
When you're really close
the river is an important source to the river mouth, obviously
As you move away from the river mouth, mussels start to become
more dominant.
away, less than 10% of the So when you get 20-25 kilometers
would be coming from the river, and over 90% would be coming
directly from mussel excretion. So a lot of the parts of the
lake fit into this category.
major river, mussels are If you're not close to any
of phosphorous. going to bWhy is that?nt source
We're not sure, but there's a couple of possibilities.
You see here in May and June
beyond that yet. of 1996-2001, we don't have data
concentrations in the spring But we had higher phosphorous
than we did previously. So we're getting a spring
slug of phosphorous.
we're seeing the same thing. If we look at river discharge,
most recent era, there's more water from the phosphorous
concentration.
slug of phosphorous coming into the lake during the spring,
just due to weather conditions
What's another possible cause of increased input from rivers?
It may be phosphorous in the soils.
This is phosphorous content of soils through Wisconsin
cropland. Just going up to '99.
What you can see is that
This is higher the steady increasing trend.
But because of fertilizer and the newer applications,
our croplands are continuing
concentration. to increase in phosphorous
storage change. What this is, is just the input
minus the output. When this reaches zero,
that means we've got a balance. But as of 1995, we were still
putting more into the soils than we were taking out of them.
Just to show you, I showed you
for the Milwaukee River. earlier the phosphorous trend
for the Manitowoc River. Here's the trend
the mid-1970s. It came down until
It's stayed pretty steady, It hasn't done much since then.
which is higher than averaging around .2 or .25,
The Milwaukee River now, the Milwaukee River.
is more around .15. So fairly high concentrations
of total phosphorous
We've got particulate phosphorous
and dissolved phosphorous entering our rivers.
That dissolved phosphorous
by the Cladophora. can be taken up directly
they can't use, or if it's fed The particulate phosphorous,
to excrete some of that oas dissolved phosphorous,ng
which is available
We also have what I'm calling the offshore loop.
A lot of this phosphorous can just bypass the near shore zone
and go right out
This is dissolved phosphorous where it becomes taken up
by plankton.
come back to the near shore, Eventually that plankton may
and then made available where to the Cladophora.sels,
And what we want to know is the relative importance
of these two loops here.
because there's a huge mass of phosphorous in Lake Michigan.
There's much more phosphorous in Lake Michigan
than what enters the lake on annual basis from the rivers.
So there's potentially a huge amount of phosphorous from here
that could be promoting Cladophora growth, if it's being
funneled in by feeding
And it's important to know from mussels.
two loops, this offshore loop theand this near shore loop,hese
because if we reduce phosphorous
if we were, by some magic, inputs into Lake Michigan,
by 50% in all of the rivers entering the lake tomorrow,
then if the near shore loop was dominant, this is
what would happen to phosphorous
in the near shore zone. Within a year, they would drop
down and we would get that 50%
It would happen very quickly. thaBut if that phosphorous isor.
flushing out into the open lake,
phosphorous to be reduced and win the open lake,r that
we're going to have to wait a much longer time.
Because, as I said, there's a huge pool of phosphorous
in the open lake. It's going to take a long time
for that respond to any decrease
coming from the rivers. This is the time span
we're looking at there. We're looking at a ten year
time span to get lake concentrations down by 50%.
That's based on the Lake Michigan program model
that was produced back
So to conclude then, in the '90s.
The primary factor responsible the main points.
in Cladophora, for the recent increase
There is a contribution from is the big water clarity.
but the main factor increais water clarity.nputs,
A secondary factor is increased phosphorous concentrations.
And mussels, appear to be the main source of phosphorous
within the near shore area. We have this increase
in water clarity. Like I said, there's nothing
we can do about it. We've got this target level
of seven micrograms per liter of total phosphorous
in Lake Michigan. And yet we still have
a Cladophora problem
What I'm suggesting is that this change in water clarity
is forcing us to reconsider this target level,
because it's not working
We may have to set a new target for the near shore waters,
because those waters
The greater light abundance has overbalanced our phosphorous
management strategies.
that at depths The Cladophora models suggest
50% phosphorous reduction would result in a significant
decline of Cladophora abundance.
the response is less certain, because we're not sure yet
how well the model works
Finally, reducing phosphorous concentrations in Lake Michigan
is a long-term process, for two reasons.
One is, as I just mentioned,
It's going to take a while the lake is this big giant.
in the watershed. The other reason, I showed you
earlier, we've been increasing
in cropland soils. phosphorous concentrations
phosphorous where, And that's this huge mass of
to be living with for a while. it's a legacy that we're going
practices right now, Even if we change our management
in the soils there's a lot of phosphorous
into the rivers and lakes that's gover decades coming
and even centuries to come. And I'll finish with that.
( applause )
But one piece that seems to be >> Interesting presentation.
You never mention sewage. We all know about the sewage,
particularly in Milwaukee and other major cities
around the Great Lakes. They've been dumping billions
of gallons in.
it's very phosphorous laden. And we all know it contains,
study and part of the solution? And secondly, probably a minor
part of it, those little white
those two-legged poop machines, birbetter known as seagulls,re,
are just out of control around the Great Lakes.
And a lot of beaches have been
haven't looked at that either. closed because of that, and you
to the sewage, but those two I suspect that's minor compared
Right. things seem to be missing here.
when we think about They'beach water quality,sues
beach closings and so forth.
With regard to Cladophora Thand to phosphorous cycling.
in Lake Michigan, sewage may be an important
local issue.
even not all of Lake Michigan, But in the larger scheme,
the area I showed you from Fox Point to Wind Point.
The sewage contribution to phosphorous flowing into
that area is negligible compared to all the other
phosphorous inputs. Even if we ignore the mussels,
just the loading from the river,
is coming from the river, from the majority of phosphorous
I intentionally don't emphasize sursewage in here, becauseand.
my concern is that I think a lot
over the last number of years, of the public has been misled
a lot of attention to sewage because the media has given
understandable, because there is overflows, and that's
with that. a health threat associated
to the Cladophora problem But tin Lake Michigan.buting
You can go to Manitou Islands and Sleeping Bear Dunes National
Park on the other side of the lake, which are ten miles
offshore, and their Cladophora
parts of the lake on this side, prand there's no sewage inputer
there.
that are causing the problem It's in-lake processes
So I'm trying to correct that we're seeing there.
of the public have that sewage the perception that a lot
the Cladophora problem, because it really isn't.
The bird issue, again,
And it ties into is an obvious health issue.
But with regard to Cladophora, the beach closing problem.
increase to the lake, and witit's really notsphorous
an important problem. Cladophora does tie in there
in that the bacteria can come from birds or other sources.
They tend to persist longer in Cladophora, so it confounds
the whole process of trying to define water quality,
because we use those as the main
And if you have this reservoir indicator of water quality.
that's either in the water of bacteria in the Cladophora
that confounds the process or sitting up on the beach,
because they may be leaching of monitoring bacteria in water,
over a longer period of time out of this Cladophora
Are you getting less than if you had no Cladophora.
from the mussels, because the water is clearer, and
there's less biomass available
There will be a negative for the mussels to filter.
Eventually, they may feedback there.
house and home, so to speak. eat themselves out of
making over the last two years, where essentially it looked like
mussels have done everything
They really have cleared up thethe water, they've reducedne.
the amount of plankton there. So I think the measurements
that we're making now are representative of the conditions
you're describing, where they're
right now. doing as little as they can
measurements in Lake Michigan to say five or ten years ago,
where the mussels excreted more phosphorous than they are today.
But I don't think it will get any less than it is now, because
they've kind of reached that
on the near shore environment. climax stage of their impact
phosphorous seems to be coming >> In this area, most of the
And what would be, to get fra 50% reduction,.
what exactly has to be done?
person to address that. Most of our work is focused on
the lake itself, and
looking at phosphorous what's going on in the lake,
and the rivers. We haven't gone much upstream
in the rivers to figure out where is this phosphorous
coming into the rivers, what are the sources,
which we need to do to really start targeting
sources that we can manage. And I'm not an expert
in that area. We do know that a lot of it
does come from non-point
Or we've done some work in the Milwaukee River
that shows that urban sources are also significant.
If you look at phosphorous
the Milwaukee River, there's concentrations as you go down
you get into the metropolitan a signMilwaukee area.e when
So there are sources there
we're guessing at now, as well, which again,
on what they are. I would just say that we still
need to be concerned about
increasing, still going up. the We need to get thatch is
Soil P concentration down.
need to reduce run-off. I think there's a focused way
to do this. And I know that folks
at UW Madison are working on
hot spots for soil phosphorous how we can highlight the
Rather than applying a strategy ruto all agricultural land,d.
try to identify the hot spots and focus your management
on those hot spots
from those hot spots. to>> Is there a possibility,f
is there something that can take care of the mussels?
Some people have worked on that, with limited success
so far, looking at pathogens
There are chemical ways to control them, but in a lake
as large as Lake Michigan,
To my knowledge, those are not options.
right now that we would put there'into Lake Michiganhogens
to try to control mussels.
in regard to that, I should mention, though,
from year to year. that mussel numbers fluctuate
in Lake Michigan. We may see mussel numbers change
over the next five to ten years.
established in Lake Michigan, and they feed on mussels.
They may put a dent in the population.
Other natural mechanisms may
We haven't monitored within rethe last couple of years,ll.
but based on our data, it looks like there are fewer mussels
now than there were two or three years ago.
We know there are hot spots along the lake shore, where
Cladophora is a big problem.
Despite the fact that Cladophora Bradford Beach is a problem.
the lake shore, and the reason is growing all along
is because of near shore for those hot spots, I believe,
the Cladophora to accumulate hydrodynamics, which force
along the shore. in certain areas
option there, but I think ultimately the management option
is to reduce the amount of Cladophora that's growing
in the lake.
one more thing. This problem is also occurring
in Lake Erie and Lake Ontario,
the point where people have to even more so than it is here, to
for part of the summer move out of their homes
because the smell is so bad. in New York on Lake Ontario,
did a large study there Thein Monroe Countyers
to look at options to manage
And they were all engineering options, trying to remove it
when it came up on the beach, trying to get it even before
it came up on the beach by pumping it away.
And in the end, none of them worked.
( applause
)