1998 WWLPT Biology Institute:
Lesson Title :ECOLOGICAL
SUCCESSION IN POND WATER CULTURES (adapted from Prentice Hall Biology
by Miller and Levine)
Target Age or Ability Group Audience
Teacher Instructions/Special Precautions
Materials & Equipment Needs
Background [Prior Knowledge
or vocabulary necessary to complete activity]
The Student Lab
Method of Evaluation/Assessment
NATIONAL SCIENCE EDUCATION CONTENT STANDARDS FOCUS
This laboratory activity will emphasize:
A. Abilities related to scientific inquiry
B. Understanding about scientific inquiry
C. Understanding about science and technology
D. Population Growth
E.Change, constancy and measurement
F. Evidence, models and explanation
G The interdependence of organisms
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 top To introduce
students to the principles of 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
Target Audience or Age Group
All Levels(Advanced and General)
Notes to the Teacher:
Required of students: Bring in pond water, dried grass, soil, jar with
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.
Class time needed: 30 minutes plus an observation period of twenty
minutes every two days for two weeks.
[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.
The lab can be introduced by asking students to discuss variables that
determine ecological succession, for example:
1. Reproductive strategies of organisms in the ecosystem
2. Environmental disruptions and interactions
3. Length of the life cycles of ecosystem organisms
4. The presence of predators
5. Nutrient Availabilty-How abundant is the food supply?
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.
Theoretically, the order of succession should appear as follows:
primary producers-- secondary producers-- primary consumers--secondary
Materials & Equipment
Needs to top
pond water culture
large jars with lids
aged tap water
glass marking pencils
glass cover slips
flexcam video camera
[Prior Knowledge or Vocabulary Necessary to Complete Activity]
This activity helps students answer:
The Student Lab to
Introduction:How can a pond water culture be used to study a succession
of populations in a community?
Purpose: To study ecological succession ina pond water culture
Equipment: pond water culture, large jars with lids, medicine droppers,
glass marking pencils, glass slides, coverslips,microscope, pH paper, flexcam
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.
Observation: Set up a data table like the sample provided:
pH of Culture Species Present
Approximate Number Of Size/Complexity
Of water culture
Individuals In Each
Conclusions 1. What organisms colonized first in the pond water culture?
2.What organisms represent the climax community?
3.Is there a relationship between pH and the number of populations?
4. Why might some populations disappear?
5. Did you observe evidence of ecological succession?
6. A stable population suddenly experiences a tremendous growth in
size. List two factors that might be responsible for this growth.
7. How is the competition between species related to the process of succession
Methods of Evaluation/Assessment
To what extent can students' data on variations in numbers be
generalized to other environments? For example, a marine coastal environment
can be used as a typical aquatic ecosystem to determine if students
can apply their data from the pond water culture. Assess students' understanding
by their answers to the conclusion questions and their ability to design
effectively the extension experiments.
Ideas to top
1. Design an experiment to determine the effect of changes in the physical
conditions (temperature, light, volume of container,etc.) on the ecological
succession that takes place in the pond water culture.
2. Design an experiment to discover how the introduction of a foreign
population into a pond water culture affects a normal succession.
3. Isolate a particular type of organism in your pond water culture.
Set up an artificial environment with ideal conditions for the growth of
the isolated species.
References Including Web Addresses
to top BOOKS
Miller and Levine
BIOLOGY Prentice Hall
Science Education Standards
for Science, Mathematics, and Engineering Education
National Research Council
2101 Constitution Avenue,NW,
Washington, D.C. 20418
with the National Science Education Standards:NABT Curriculum Review Instrument
NABT Task Force on the National Science Education Standards