(	BETTY JEAN JONES

 

NATIONAL SCIENCE EDUCATION NON-CONTENT STANDARDS FOCUS
This laboratory activity will emphasize:
A. Teaching strategies that allow for meaningful discourse among students
B.Suggested outside resources
C. Inquiry as a way of learning
D. Clear goals and expectations
E. Adequate time allotment for learning to take place
F. Curriculum coordination with mathematics

•  Many  examples of ecological succession would  be studied over a period of several years because it takes a long period of time for ecological succession to occur in the environment. However , a pond water culture can be used as a small-scale model of ecological succession  to show results in a relatively short period of time. In this investigation, students will use a pond water culture to study  ecological succession.

• To let students investigate how a pond water culture can be used to study a succession of populations in a community.
• To engage students in scientific inquiry
• To allow students to investigate population growth
•  To continue study of biological models
• To coordinate the curriculum with mathematics

• Biology students
• All Levels(Advanced and General)

Notes to the Teacher: to top

1. Required of students: Bring in pond water, dried grass, soil, jar with lid
2. Preparation time neededThe pond water culture may be set up with aquarium  water or with water samples collected from a local pond, lake,or stream.  A nutrient medium for the culture may be prepared by boiling hay, dried grass, or lettuce in aged tap water for 10 minutes. Allow the nutrient medium to cool and add it to the pond water culture.
3. Class time needed: 30 minutes plus an observation period  of twenty minutes  every two days for two weeks.
4. [Hazards/Precatuions]Safety Wear a laboratory apron if one is available. Handle all glassware with care. Always handle the microscope with extreme care. The student is responsible for its proper care and use. Use caution when handling glass slides because they can break easily and cut you. Note all safety alert symbols next to the steps in the procedure and review the meanings of each  symbol by referring to a safety symbol guide.
5. The lab can be introduced by asking students to discuss variables that determine ecological succession, for example:
6. 1. Reproductive strategies of organisms in the ecosystem
7. 2. Environmental disruptions and interactions
8. 3. Length of the life cycles of ecosystem organisms
9. 4. The presence of predators
10. 5. Nutrient Availabilty-How abundant is the food supply?
11. Students should also be asked to make some predictions about the order of ecological succession in their pond water cultures. What changes do they expect to see over the 2 week period in terms of displacement of organisms. At the end of the 2 week period, the students can compare their expected results with their observed results.
12. Theoretically,  the order of succession should appear as follows: primary producers--  secondary producers-- primary consumers--secondary consumers.

1. Introduction:How can a pond water culture be used to study a succession of populations in a community?
2. Purpose: To study ecological succession ina pond water culture
3. Equipment: pond water culture, large jars with lids, medicine droppers, glass marking pencils, glass slides, coverslips,microscope, pH paper, flexcam video camera
4. Procedure:1 Make some predictions about the order of succession. In some hypotheses, describe the changes you expect to see as you observe the community for 2 weeks At the end of the 2 week period, you will compare your expected results with your observed results.2.  Obtain a pond water sample . Use a glass marking pencil to put your group  member's names on the outside of the jar. Carefully examine the culture. Observe the color, cloudiness, odor, and any layering of materials that may occur. Record the date and your observations in the data table.3. Remove the lid from the culture jar and make three wet mount slides of the pond water culture. Take the sample for each slide from a different part of the culture jar- top, middle, and bottom.4. Examine each slide under a microscope, first low power, then under high power. Note:  Microscope measurements should be completed prior to beginning the lab. Measure diameter of the low and high power field of view, by drawing circles to fit the microscope field of view and measuring it. To determine the diameter of the high power field of view, multiply the magnification of the low-power objective times the diameter of the low  power  field of view and divide by the magnification of the high power objective.To determine the area of the field of view, use the formula: A= 3.14 times radius squared, 3.14 is pi. The importance of knowing the diameter and the area of the field of view is that it gives a more proper sense of scale to the organisms being viewed. It will be useful in determining the number of organisms within the field of view.5. Use  drawings of plantlike protozoans and other typical pond water organisms,(ciliates, flagellates, sarcodines, etc.) to identify the organisms you might observe in your pone water culture.6. Use pH paper to test the pH of the pond water culture in the jar. Record this information in the data table. 7. Repeat steps  2 through 6 every two days for a period of two weeks.8.  Construct a line or bar graph of the growth of any organism of your choice.
5. Observation:  Set up a data table like the sample provided:
6. Data Table
7. Date    Appearance            pH of Culture      Species Present       Approximate Number Of      Size/Complexity
8.            Of water culture          Water              In Culture              Individuals In Each                    Of Organisms
9.                                                                                                       Population
10. Conclusions 1. What organisms colonized first in the pond  water culture?
11. 2.What organisms represent the climax community?
12. 3.Is there a relationship between pH and the number of populations?
13. 4. Why might some populations disappear?
14.  5. Did you observe evidence of ecological succession?
15. 6.  A stable population suddenly experiences a tremendous growth in size. List two factors that might be responsible for this growth.
16. 7. How is the competition between species related to the process of succession ?

to top BOOKS
          Miller and Levine BIOLOGY Prentice Hall
          BSCS Biology

           DOCUMENTS
           National Science Education Standards
           Center for Science, Mathematics, and Engineering Education
            National Research Council
            2101 Constitution Avenue,NW,
             HA 450
             Washington, D.C. 20418

            Aligning with the National Science Education Standards:NABT Curriculum Review Instrument
             NABT Task Force on the National Science Education Standards
 

          WEB Sites
           http://www.fedlabs.org/flc/rogers/rlabs.3611-05htm
           http://www.glerl.noaa.gov
           http://www.usgs.gov/tech-transfer
           http://ctoserver.arc.nasa.gov/