Lesson 1

Does the increased use of fertilizers effect biodiversity?

Objectives:
Students will be able to:

determine if the introduction of fertilizers can effect the biodiversity of an aquatic ecosystem.
evaluate how the introduction of fertilizers can change an aquatic ecosystem in a simulated system.

Note: Safety goggles and aprons should be worn at all times during this lab activity.

Materials:
Water sample from a local stream or pond
1000 milliliter beaker or large container
3 500 milliliter beakers or jars to set up miniature water ecosystems
Dissecting microscope and hand lenses
10% fertilizer solution in dropper bottles
20% fertilizer solution in dropper bottles
Graduated cylinder
Nitrate test kit (Chemical) or Nitrate test strips
Phosphate test kit (Chemical) or Phosphate test strips
Petri dishes
Pipettes

Procedure:
Working with a partner:
1. Working with a partner, take an approximate 1000 ml sample of the water sample from
a local stream or pond.
2. Pour a portion of the sample into a petri dish and examine it under low power on the
microscope or with a hand lens.
3. Provide a detailed description of the water sample. What types of organisms are found?
Is there an abundance of algae and plant life?

4. Test the nitrate and phosphate levels of the water sample.
Initial nitrate reading:

Initial phosphate reading:

5. Separate the water sample into the three beakers or jars and label as follows:

Beaker 1-Control-no additions
Beaker 2-10% fertilizer solution
Beaker 3-20% fertilizer solution

6. To beaker 1, the control, do not add any additional materials.
7. To beaker 2, 10% fertilizer, add 2 milliliters of 10% fertilizer solution. Stir after the
addition of the fertilizer solution.
8. To beaker 3, 20% fertilizer, add 2 milliliters of 20% fertilizer solution. Stir after the
addition of the fertilizer solution.
9. Place the 3 beakers in an area where they will be undisturbed for a 24 hour period.
10. Based on the levels of fertilizer solution in each container, hypothesize how the
biodiversity of each water sample will change over the 24 hour period. Will the organisms
increase or decrease? Will the plant material and algae increase or decrease?

Hypothesis:

11. After the 24 hour period, place a portion of each of the water samples from beakers 1,
2 and 3 in a petri dish and examine it under low and high power on a dissecting
microscope. Provide a detailed description of each sample. Record your description in the
appropriate column in the data table
12. Test the nitrate and phosphate level of each sample and record the number in the
appropriate column in the data table

Data Table:

After the observations are complete, answer the following questions

Conclusions:
1. Does the data collected support your hypothesis? Why or why not?

2. Based on your observations, how does the increase of nitrates and phosphates due to
the overuse of fertilizers effect biodiversity?

3. How would an increase in fertilizers around an aquatic ecosystem such as a pond or a
stream, effect the plant and animal life?

4 Research how fertilizers are used and how a determination is made on the levels and the
amounts to apply to farmland. Describe other sources of nitrates and explain how they end
up in aquatic ecosystems and the effects they have when found in excess.

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e-mail the author ©1998 April J. Cleveland for Science Junction, NC State University. All rights reserved. page design by Lisa Leonor Grable and April J. Cleveland URL: http://www.ncsu.edu/sciencejunction/depot/experiments/water/lessons/np/nplesson1.html Last Modified: 6/9/98 | Data Depot | Science Junction | NC State University |