Chapter 13 Ecological Principles • MHR 4597.Devise a sampling procedure (be sure to include
sample size, procedure, timetable and frequency of
sampling, and sampling instruments) to measure
changes in productivity and biomass of the target
organism(s) at each trophic level in each model
ecosystem. Ensure that your sampling techniques
will provide an accurate estimation without unduly
disturbing the integrity of the ecosystems.
8.You may wish to set up and run the ecosystems for
a period of time to ensure they are stable, and to
give you an opportunity to sample and identify the
various species inhabiting your systems. You may
also wish to monitor biotic and abiotic conditions
such as temperature, water transparency, nutrient
content, population size of various species, and the
pH of the water. The data derived from this initial
sampling could provide you with a baseline or
standard for your subsequent experimental
observations.
9.Design a procedure for evaluating the effects of
changing the selected variable and measuring
ecosystem response.10.Your procedure should provide quantitative as well
as qualitative data. Determine how your sample
data could be translated into specific biomass
values at each trophic level for the food webs in
your model ecosystems.
11.Determine your method of data analysis. Select the
format for graphs and charts that will illustrate most
effectively how key parameters of your ecosystems
responded to the variables manipulated in your
experimental procedures.
12.Establish the amount of time you will require. Ask
your teacher to approve your experimental design
and your safety plans and arrange for the equipment
and materials you require.
Checking the Plan
1.Describe the dependent and independent variables
in this investigation.
2.What will you measure and how?
3.Design a table to record your data and observations.
4.Select the factors to be graphed, such as sunlight
versus biomass.Data and Observations
Conduct your investigation and record the observations
and measurements. Enter your data on a summary table
and graph your results.Analyze
1.Describe any changes in biomass production and
other factors in your ecosystem models over the
duration of the experimental procedure.
2.What did the results indicate about how the variable
tested for in this procedure affected biomass at
each trophic level?
3.Compare the biomass of heterotrophs with the
biomass of autotrophs.
4.How did your results relate to your original
hypothesis?
5.Discuss possible sources of error in your procedure
(relating to such factors as the sampling procedures
used and the ability to control extraneous variables)
that may have influenced your results.
6.How do the results of your group compare with the
data provided by the other groups working on
similar variables? Did dividing the class into groups
provide you with a more complete understanding of
the effects of certain variables on the quality of
functioning ecosystems?Conclude and Apply
7.What can you conclude about the accuracy of your
original hypothesis?
8.How could your original procedure be improved?
9.Discuss the benefits and drawbacks of studying
model ecosystems rather than studying actual
ecosystems in the field.If you have access to probeware, do the activity
“Temperature and Dissolved Oxygen Use by Goldfish.”Probeware