Teacher Copy, Level 2
Name_________________
Marvelous Mud
Featured scientist: Lauren Kinsman-Costello from Kent State University
Research Background:
The goopy, mucky, (sometimes stinky!) mud at the bottom of a wetland or lake is a very
important part of the ecosystem. Mud is basically wet soil, but because it has different
properties than soil because it is wet most of the time. Mud is usually dark brown
because it contains partially decomposed plants, called organic matter. Dead organic
matter tends to build up in wetlands. Organic matter decomposes more slowly under
water than on land. This is because underwater microbes do not have all the oxygen
they need to break it down quickly.
Under the right conditions, mud can act like fertilizer for a wetland. Nutrients, such as
phosphorus, tend to build up in mud. This makes mud an important source of the
phosphorus that algae and other plants need to grow. As a graduate student at
Michigan State University, scientist Lauren was interested in what helped phosphorus
stick to mud. She also wanted to know why phosphorus builds up more in some
wetlands than others.
Although most mud is high in organic matter and high in nutrients, all mud is not created
equal! The amounts of organic matter and nutrients are different from one ecosystem to
the next. How quickly these materials enter or leave the mud may also change across
ecosystems. Even within the same ecosystem mud can be very different from place to
place. The molecules in organic matter could be a major source of phosphorus in mud.
This would mean that wetlands with more organic matter would have more phosphorus.
You can tell that the mud in this picture is high in organic
matter because it is dark brown and mucky (in real life you’d be
able to smell it, too!)
Scientist Lauren holding a successful mud
core. You can see that the tube has mud,
as well as some water.
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Name_________________
Teacher Copy, Level 2
Scientist Lauren measured organic matter and phosphorus in mud from 16 ecosystems
(four lakes, five ponds, and seven wetlands). She wanted to determine if there was a
relationship between the amount of organic matter and the amount of phosphorus in
mud.
Scientific Question: Is organic matter an important source of phosphorus in mud?
What is the hypothesis? Find the hypothesis in the Research Background and underline
it. A hypothesis is a proposed explanation for an observation, which can then be tested
with experimentation or other types of studies.
Scientific Data:
Use the data below to answer the scientific question:
Ecosystem
Wintergreen Lake
Douglas Lake
Jackson Hole
Whitford Lake
Pond 9
Pond 18
Pond 10
Pond 23
Pond 6
Loosestrife Fen
FCTC
Osprey Bay
Turkey Marsh
Sheriffs Marsh
Brook Lodge
Eagle Marsh
Ecosystem Organic
Type
Matter (%)
Lake
Lake
Lake
Lake
Pond
Pond
Pond
Pond
Pond
Wetland
Wetland
Wetland
Wetland
Wetland
Wetland
Wetland
24%
55%
5%
1%
21%
24%
17%
19%
6%
40%
80%
8%
15%
30%
18%
4%
Total
Phosphorus
(ug P/g d.w.)
528
523
105
28
556
512
537
366
177
773
1441
167
459
1909
443
130
What data will you graph to answer the question?
Predictor variable: Organic Matter
Response variable: Total Phosphorus
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Name_________________
Teacher Copy, Level 2
Draw your graph below:
Total Phosphorus (ug P/g d.w.)
2500
2000
1500
1000
500
0
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Percent Organic Matter
Interpret the data: Make a claim based on the evidence that helps answer the original
research question. Connect the pattern in the data to a pattern in the natural world.
Justify your reasoning using data.
The data supports the hypothesis that a lot of the phosphorus in
wetland mud is contained in molecules of organic matter. The
amount of organic matter is positively related to the amount of
total phosphorus in mud. Meaning, when mud has more organic
matter it also has more total phosphorus. In the scatter plot
graph of total phosphorus versus organic matter in mud samples,
you see that there is a linear, positive relationship between
percent organic matter and total phosphorus. Although, there are
a few points that do not follow the general pattern (they
“deviate from the relationship”). Note that these points
deviating from the linear relationship occur only at higher
organic matter and phosphorus levels.
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Teacher Copy, Level 2
Name_________________
Your next step as a scientist: Science is an ongoing process. Did this study fully answer
your original question? What new questions do you think should be investigated? What
future data should be collected to answer them?
The relationship in these data is a correlation. Therefore,
while it provides evidence that phosphorus is being stored in
organic matter in mud, it doesn’t conclusively prove this. To
prove this, I would run chemical analyses on the mud that would
show the kinds of molecules that phosphorus is a part of in the
mud, and I would be able to tell if these molecules were from
decaying plant material (organic matter) or not.
You’ll notice that some of the points don’t follow the same
straight line as the others. For example, the point for Douglas
Lake has less total phosphorus than we’d expect based on its
amount of organic matter and the relationship that the other
points show. It’s interesting to think about why this might be.
Is the organic matter in this ecosystem somehow different than
the organic matter in the others? It could be organic matter
from different kinds of plants, or have been decomposed less or
more than the organic matter in the other systems.
These data also lead us to the question: how well does the
organic matter store phosphorus in mud? Or, how well does the
phosphorus stick in that mud. If we put the mud under different
conditions, like in warmer conditions or dryer conditions, does
some of that phosphorus move from mud into the water? If it
moves into the water, it can flow into other freshwater
ecosystems and cause unwanted blooms of algae.
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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