Hello, this is Annabel, Molly, Sara and Susanna's site on mollusks.  Enjoy!!!


      Mollusks can be found in both freshwater and soil.  At least 35,000 species are present in soil and are normally found in the upper or litter layer of soil.  The population density of mollusks is affected by precipitation rates, soil structure, and chemical distribution in the soil.  For our experiment we decided to look at the amounts of calcium along with the population density of mollusks and pH levels. Mollusks require a higher amount of calcium in order to provide the nutrients needed for their shells. We predicted that there would be a positive correlation between pH and calcium levels.  Our group decided to focus the experiment on mollusks because their presence in site two (This site contains an urban stream located directly below a dam with soil that is consistently moist.  It contains higher algae and arthropod populations than most sites. Also Site Two contained more plant species, a high level of calcium, low potassium levels, average salt levels, predominately loamy sand and pH of 6.4, which is slightly acidic.) interested us and we wanted to find out how their population density compared in different environments.  Before we could begin our experiment we had to do an initial survey.  This included finding out the population density and biodiversity of arthropods, plants and the population density of worms, bacteria, protozoa, algae, and fungi along with soil texture, pH and salts. The survey did not show a positive correlation between pH level and calcium.  Traditionally, as the pH increases the calcium level should increase (a correlation should be present)[1]. His advice led us to our hypothesis; there will be a positive correlation between levels of calcium and pH and therefore a higher population density of mollusks.

[1]  Dr. Peter Groffman PhD, Conversation at E.S.S.R.E meeting, July 2001.



Suzifer being devilish          Suzifer attempting to possess "Sparkles"


1. Locate thirteen different sites where you can take soil samples. For example: one near a wooded area and another near a pond, etc.

2. Take a soil sample from each site using a core sampler to the first mark (15 cm). Use gloves to remove the soil into a plastic bag sealed and labeled with the site number.

3. Label each site by marking with a flag. For our flags we placed a plastic glove over a stick, which worked very well.

4. In order to attract the mollusks, purchase snail bait, which can be found in any hardware store.  Place 20 grams of snail bait in a pile at each site. Cover bait with cheesecloth. Wet the cheesecloth until saturated.

5. Leave traps for at least 60 hours.  After time has passed, go back to sites and count the number of mollusks.  Record data.

6.  Test each sample for calcium in parts per million. We recommend using the LaMotte soil test kit. 

7. Test each sample for pH.  Again, we recommend using the LaMotte soil test kit. 

8. Graph results and note correlation.  We graphed the mollusk vs pH data on one graph; the mollusk vs calcium data on a second graph; and the calcium vs pH data on a third graph.



While trying to "catch" the mollusks we ran into some problems.  Make sure not to use plastic containers to hold the bait, or any containers, simply place it on the soil and cover it with cheesecloth. The mollusks should not die but should still come for the bait.

When looking for the mollusks you might want to use a magnifying glass because the mollusks are very small and can sometimes look like dirt.

Make sure you wear gloves while handling the snail bait because it is very toxic to the skin.  DO NOT CONSUME!

Also, you should measure your snail bait BEFORE you go into the field and keep it in separate plastic bags.


Sample Results:

Susanna Ingalls, Molly Malloy, Annabel Acs, Sara Katz
PH Data
Sample Duplex Indicator Specific Indicator
1 8 7.2
2 7 6.4
3 8 7.2
4 5 4.2
5 7 6.4
6 7 7.2
7 8 7.2
8 7 6.4
9 7 7.2
10 8 7.2
11 8 7
12 6 5.4
13 8 7.2
Calcium Data
1 1400ppm
2 150ppm
3 1400ppm
4 0ppm
5 150ppm
6 1000ppm
7 700ppm
8 0ppm
9 1000ppm
10 700ppm
11 7700ppm
12 150ppm
13 2300ppm
Mollusks Data
Sample         Day 1
Both Snails Slugs
1 3 3 0
2 2 0 2
3 0 0 0
4 4 2 2
5 6 0 6
6 3 0 3
7 24 0 24
8 1 0 1
9 15 0 15
10 1 1 0
11 0 0 0
12 0 0 0
13 4 0 4
PH Calcium Mollusks
mean N/A 842.307 4.846
meadian 7.2 700 3
mode 7.2 150 0
maximum 7.2 2300 24
minimum 4.2 0 0
range 3 2300 24
std. Deviation N/A 735.591 6.724
std. Error N/A 1286.858 397.756 8.91 0.782
variable N/A 541049.1 45.212



Bibliography: Follow this link for more information

Hall, Geoffry S.. (1996) Methods for the Examination of Organismal Diversity in Soils and Sediments. New York: Cab International. 

“Soil Health.” [Available Online], http://ice.agric.uwa.edu.au/soils/soilhealth/organic/index.htm ; 2001

“Microbe Zoo, Dirtland.” [Available Online], http://commtechlab.msu.edu/sites/dlc-me/zoo/zdmain.html ; 2000

“The Soil Foodweb: It's Importance in Ecosystem Health.” [Available Online], http://www.rain.org/~sals/ingham.html ;undated

“Microbiology of Agricultural Soils.” [Available Online], http://www.ucc.ie/impact/agri2f.html#ecosystem ; undated

 “Soil Fauna and Agriculture: Past Findings and Future Priorities” [Available Online] http://eap.mcgill.ca/Publications/EAP25.htm ;1985

Ingham, Elaine R. "Chapter 3: Bacteria- The Living Soil: Bacteria." [Available Online] http://www.statlab.iastate.edu/survey/SQI/SoilBiology/bacteria.htm; February 2001.

Lipscomb, Diana. "Protozoa." [Available Online]  http://biology.usgs.gov/s+t/noframe/m2083.htm; Date N/A.

Kirkby, Clive. "Biodiversity, Soil and Ecologically Sustainable Development." [Available Online] http://chm.environment.gov.au/archive/soil.html; Date N/A.

"Biodiversity." [Available Online] http://esa.sdsc.edu/biodiv2.htm; 1988.

Borden, Dr. Robert C. "Protozoan grazing to be investigated as an important control on rate of biodegradation of hydrocarbon contaminants." [Available Online] http://www2.ncsu.edu/ncsu/CIL/WRRI/annual/97borden.html; June 1997.


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