I. Chase Lake Lab
II. Problem
How is the biodiversity of soil samples affected by the proximity of their location to the waterline, measured both into and away from the water?
III. Hypothesis
I expect that the biodiversity of soil samples will increase as they descend more and more into water. Water is one of the most important molecules needed to sustain life, and underwater there should be ample amounts of it. More terrestrial locations might not be so readily supplied. Also, as samples on land move farther and farther away from the waterline, they will be moving closer and closer to paths, and areas that humans walk through. These sections that have been graveled over, etc. are not in their “natural state,” and their biodiversity has probably, consequently, suffered.
IV. Variables
A. Independent: distance of soil sample from water line, measured in feet (2 foot increments)
B. Dependent: number of and species of organisms found in soil: biodiversity of soil
C. Controlled Variables: Temperature and weather of day on which samples were taken, depth of sample, amount of dirt taken, time given for organisms to filter
V. Materials
Trowel
14 Ziploc bags
Sharpie permanent pen
Tape measure
Microscope
14 observation trays
14 ring stands
14 clips
14 lamps
Paper, pen, ruler
VI. Procedure
A. find a location near the lake where you can measure 6 feet into the water and 6 feet out of the water, all in a straight line
B. use the trowel to sample 1 cup of dirt from the waterline, and put it in a Ziploc bag. Seal the bag, and label it “waterline, location #1”
C. measure 2 feet into the water, use the trowel to take a soil sample from the bottom of the lake, also of one cup of soil. Put the soil in a second Ziploc bag and label it “2 feet in, location #1”
D. repeat step 3 measuring 4 feet into the water and 6 feet into the water. Label all bags accordingly.
E. measure 2 feet away from the waterline in the other direction, onto land. Use the trowel to take a soil sample, also of one cup of soil. Put the soil in a new Ziploc bag and label it “2 feet away, location #1”
F. repeat step 5 measuring 4 feet away and 6 feet away, and label bags accordingly
G. repeat steps 1-6 for a second location, labeling “location #2” instead of “location #1”
H. take all bags back to the lab, where you can set up the funnels
I. clip each funnel onto a ring stand, so that its mouth is positioned over an observation dish. Position a lamp so that it is shining onto the wide end of each funnel. Fill each observation dish with water
J. empty each Ziploc bag into a different funnel, keeping the bags with the corresponding funnel set-up, for labeling purposes
K. leave the samples overnight, so that organisms filter through each funnel’s netting into the observation dishes below
L. use the microscope to count the number of each kind of species in the first tray, and record along with any observations
M. repeat step 11 for each other tray
- Data
Number of Each Type of Species at Location #1
Position In Relation to Waterline(feet +/-inch) / Organisms and Number of Each Seen
A / B / C / D / E / F
6 feet into water / 3 / 6 / 66 / 11
4 feet into water / 25 / 1 / 1
2 feet into water / 0
Waterline / 1
2 feet onto land
4 feet onto land / 2
6 feet onto land / 2
Number of Each Type of Species at Location #2
Position In Relation to Waterline(feet +/-inch) / Organisms and Number of Each Seen
A / B / C / D / E / F
6 feet into water / 3 / 1 / 2
4 feet into water / 3 / 3 / 3 / 6 / 1
2 feet into water / 2
Waterline / 7 / 1 / 1 / 30 / 38 / 1
2 feet onto land
4 feet onto land / 53 / 1 / 1 / 1 / 1
6 feet onto land / 2 / 1 / 1 / 2
- Data Analysis
- Calculations
Sample Calculation: D= when N= total number of organisms and
n= number of the specific species
6 feet into water, location #1:
N= 3+6+66+11= 86
=
== 1.648
Diversity Values For Location #1
Position In Relation to Waterline(feet +/-inch) / Biodiversity
(D value +/- 0.001)
6 feet into water / 1.648
4 feet into water / 1.170
2 feet into water / 0.000
Waterline / 0.000
2 feet onto land / 0.000
4 feet onto land / 1.000
6 feet onto land / 1.000
Diversity Values For Location #2
Position In Relation to Waterline(feet +/-inch) / Biodiversity (D value)
6 feet into water / 3.750
4 feet into water / 5.000
2 feet into water / 1.000
Waterline / 2.591
2 feet onto land / 0.000
4 feet onto land / 1.158
6 feet onto land / 7.500
- Graph
- Conclusion
A. Conclusion
Our results at Location 1 were fairly conclusive, but our results at Location 2 were all over the place. At Location 1, the farther one moved from the waterline the more biodiversity there was. At the waterline and 2 feet inland, the diversity value was 0. At 4 feet in and out, though, the biodiversity was 1 and 1.17 (respectively). This was a gradual increase. At 6 feet in, then, the biodiversity was 1.648. This was another small increase. The graph for location 1 values, above shows a gradual decrease as one moves closer to the waterline (at the y-axis) from deeper water (the left), and then a mirrored gradual increase as you move away from the line inland (to the right).
Location 2 results were very inconclusive. A wave is created by the scatter point, as seen clearly in the graph of location #2 above, but rather than points aligning themselves on a predictable curve, in this case this only means that points alternate between increases and decreases. It’s possible that from looking at the two of these locations one might decide that biodiversity comes in waves- with bands of more and less diverse regions. More transects, though, would be needed for any sort of credibility.
B. Sources of Error
The largest source of error in this experiment was the small sample size. We only tested two locations, meaning that there could have been extenuating circumstances at these two spots, which we would never be able to realize, since there was not a larger body of data to compare them to. We also only took one sample from each of the distances at each location. This was not enough to have total confidence in our results.
Another source of error was that we only gave the samples one day to filter, as opposed to 48 hours. If we had given them more time, more organisms might have fallen through to the observation trays. If certain samples were dumped so that particularly organism-rich portions were at the top, as opposed to at the bottom, of the funnel, we might not have given certain distances the biodiversity credit that they deserved.
Our final source of error was that we had multiple people observing trays. Because we had so many and only a little time to do them in, we had three people observing trays at once. While this should not have made a huge difference, one person may have been looking more closely, had their microscope better focused, etc.
C. Improvements/Extensions
If I were to conduct this experiment again, I would make more transects from the lake. That way, we could get a variety of shaded areas, areas in sun, areas where the “land” portion was dirt, areas where it was grass, etc.
I would also take more samples from each distance; 3-5 soil scoops next to each other might help prevent missing an outlier, if one of them was contaminated/not accurate.
Finally, it might be better to go at the experiment from a slightly different angle- look at water depth, as opposed to distance into the lake. Specifically, in some areas there is a gradual drop when you hit the water, and in others it is steep. It might be better to measure, for instance, 2 inches deep, 6 inches deep, and 10 inches deep, as opposed to 2, 4, and 6 feet in.