Aquatic
Respiration in a
Name: Audrey Smith
Title of
lesson: Aquatic Respiration in a
Date of
lesson: Day 8
Length
of lesson:
One 50 minute
class period
to collect data, additional time to compile data.
Description
of the class:
Course
Title: What is the trophic state of
Grade
level: 9-12
Source of the lesson: http://waterontheweb.org/curricula/bs/teacher/aquatic/teaching.html
Biology:
2) Scientific processes. The student uses scientific methods during field and laboratory investigations.
The student is expected to:
(B)
collect data and make measurements
with precision;
(C) organize, analyze, evaluate, make inferences, and
predict
trends from data; and
(D) communicate valid conclusions.
9) Science concepts. The student knows metabolic processes and energy transfers that occur in living organisms. The student is expected to:
(D)
analyze the flow of matter and energy
through different
trophic levels and between organisms and the physical environment.
12) Science concepts. The student knows that interdependence and interactions occur within an ecosystem. The student is expected to:
(A)
analyze the flow of energy through
various cycles
including the carbon, oxygen, nitrogen, and water cycles.
The
Lesson:
I. Overview
Students will use the internet to investigate the effects of respiration on water chemistry and a lake ecosystem.
II. Performance or learner outcomes
Students will use Water on the Web data (http://waterontheweb.org) to explore the affects of respiration on the water chemistry of lakes. In this lesson students learn that the simple act of respiration can have profound effects on an ecosystem.
Students will be able to:
1.
Provide data collected from
microcosms and RUSS
(Remote Underwater Sampling Station) monitored lakes as evidence that
respiration occurs and can be quantified in aquatic settings.
2.
Describe the effects of respiration
on a body of
water.
3.
Design an appropriate water sampling
regimen for
assessing pH and DO (or the selected water quality measure in the
student
inquiry lesson) in the hypolimnion
of a lake.
4.
Explain how organisms affect pH and
DO (or the
selected water quality measure in the student inquiry lesson) in the hypolimnion of a lake.
III. Resources, materials and supplies needed
This
lesson requires
access to Water on the Web data (http://waterontheweb.org).
Each
group of three
students gets a three page handout (handout follows the lesson plan)
IV. Supplementary materials, handouts.
This
lesson assumes
that the students already have an initial lesson on water chemistry and
how
water is analyzed and they are familiar with the concept of communities
and
food webs.
Five-E
Organization
Teacher Does Student Does
|
Engage: Present this scenario to the
students: Your lakeshore association has decided it can afford to have six water quality analyses done on the lake during the summer (between May 1 and November 1). Your group needs to select one date and time per month to conduct those analyses. Record your groups' choices of analysis dates and times in the table below
Questions What contributes to changes on pH? Where does the oxygen in water come from? What organisms use the oxygen? |
Student Activity Students come up with reasons why aquatic respiration might be an issue for the lake association. Discuss uses of a lake for humans and other organisms. Student Response Students may know that the oxygen comes from plants and algae. Some may think that because water is part hydrogen and part oxygen, this fulfills the oxygen requirements of aquatic organisms. |
Evaluate
|
Explore: Learning Experience(s) Remind students of the need to carefully collect and record their data. Students also need to reflect on the quality of the data. There is always the possibility that inaccurate data have been collected or posted to the WOW web site. Scientists need to reflect on the quality of any data that are used. Remind students to label the axes and include proper titles, legends, and units of measure.
Questions What is detritus? What are some examples? Which lake will you investigate? |
Student Activity Students work in groups of 3. Groups access RUSS data on the internet. Each group needs to select a lake, determine one date and time per month to take data. Each group records data for their chosen dates and times. Students graph dissolved oxygen and pH for their sampling periods. They should be reminded to label the axes and include proper titles, legends, and units of measure
Student
Response Detritus is the organic matter that falls into a lake and decomposes. Leaves would be an example, also dead organisms. |
Evaluate
|
Explain: Learning Experience(s) A steady "rain" of detritus
(dead stuff, mostly algae
and particulate material washed into the lake from the watershed)
falls to the bottom of lakes. This "rain" of detritus is greatest
during the most productive time of year. This productivity
coincides with the period when lakes are thermally stratified for long
periods of time (in CO2 + H20 <-----> H2CO3 <-----> H+ + HCO3- Discuss the students’ results. (Brief oral presentations by the student lab groups can be useful in comparing group approaches and results).
Questions Which dates would you choose and why? Over the course of the summer,
did pH and DO continuously decline near the bottom of the lake? What similarities and
differences are observed in comparing the group graphs and results? Why might some lakes have
sudden changes in DO and pH near the lake bottom during the summer? |
Student Activity Identify any possible flaws in the experiment setup. Take data and record observations. Begin lab report (students will have to finish lab report outside of class or the following class period).
Student Response Students should be prepared to present their data informally the class. pH and DO should decline due to bacterial respiration and the release of carbonic acid. Could be due to mixing by wind. |
Evaluate
|
Extend / Elaborate: Learning Experience(s) Lakes that remain stratified and are highly productive will usually demonstrate a continuing decline in pH and DO during the summer months due to bacterial action in the sediments. Some lakes may go anoxic (lacking any DO in the depths). Other lakes may have sudden increases in DO and pH if the water is mixed through events such as high winds (this also depends on basin shape and lake depth).
Questions Do we have information on basin shape and lake depth? Can we make hypotheses whether these factors affected data? Where are these lakes? Are there any lakes
like this in |
Student Activity The next lesson could be a computer simulation of factors that change the land use or population around the lake.
Student Response If data is available, students can make hypotheses. Many of the lakes on which data have been
collected are in Lakes in |
Evaluate
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Aquatic
Respiration in a |
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