teacher pages plankton and co₂ - cce...

8
Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations of dissolved gases like carbon dioxide (CO) and dissolved oxygen (DO) in marine environments. Through the process of photosynthesis, millions of phytoplankton in the ocean use the reactants carbon dioxide, water, and energy from the sun to produce sugar (glucose) and oxygen. Living organisms use the products of photosynthesis (glucose and oxygen) to respire and gain energy (ATP). As a result of respiration, water and carbon dioxide are released as byproducts. Photosynthesis and respiration remain in equilibrium as long as the populations of plants and animals remain in balance and conditions within the environment remain stable. A change in the abundance of organisms or the concentration of dissolved gases like carbon dioxide and oxygen will affect the chemistry in the ocean. This in turn affects the pH balance of seawater and impacts many biological processes. If the pH increases, it causes the water to become more “basic.” In other cases, if the pH decreases, then the water becomes more acidic. A drop of one pH unit corresponds to a 10-fold increase in the concentration of charged particles in the water, making it more acidic (Doney, 2006). The pH of seawater ranges from 8.0 to 8.3, meaning that the ocean is naturally somewhat basic. Changes in water chemistry of ocean ecosystems affects the health and survival of organisms over time. Target audience: Grade 9-12 Biology, Marine Science, or Environmental Science Time Frame: Initial set-up and data collection will take one lab period (one hour) and final data collection and conclusion will be one lab period (one hour). This experiment can be extended up to five days of observations. Purpose: In this simulation, groups of students will record and observe the impact of plants (Elodea) and animals (brine shrimp) on carbon dioxide, dissolved oxygen and pH levels in a marine environment. They will review and discuss the processes of photosynthesis and respiration as vital biological processes and the impacts of changes in the processes on the health of the phytoplankton and zooplankton over time. CA standards addressed: Life Science standards- 1f,1g, 6b , 6d. Earth Science Standard 7a. Investigation and Experimentation 1a, 1b, 1c, 1d, 1j, 1k,1m. National Science Standards: NS.9-12.1 SCIENCE AS INQUIRY - Abilities necessary to do scientific inquiry investigations and understand scientific inquiry NS.9-12.6 PERSONAL AND SOCIAL PERSPECTIVES - Environmental quality NS.9-12.7 HISTORY AND NATURE OF SCIENCE - Nature of scientific knowledge TEACHER PAGES Created by: Beth E. Simmons © 2009 (Revised 2011) Education & Outreach Coordinator CCE Long Term Ecological Research (LTER) Disclaimer: May be reproduced for educational purposes; cite appropriately pH and Carbon Dioxide The pH scale has values from (0 to 14) with 7 being neutral pH > 7 (alkaline) pH < 7 (acidic) pH of the ocean normally ranges from 8.1 to 8.4 at the surface pH is directly influenced by carbon dioxide levels Animal Activity: Increases acidity (lower pH values) respiration decreases Olevels and increases COlevels Plant Activity: Decreases acidity (higher pH values) increases Oand decreases COfrom the water through photosynthesis Plankton and COWhat impact do phytoplankton and zooplankton have on CO, DO and pH levels in marine environments? A Partnership between California Current Ecosystem Long Term Ecological Research (CCE LTER) and Ocean Institute (OI) Beth Simmons, Education and Outreach Coordinator, CCE LTER, Scripps Institution of Oceanography, Christy Millsap, Teacher, Rancho Bernardo High School, San Diego, California. LESSON TWO 1

Upload: others

Post on 09-Jul-2020

18 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Introduction:Phytoplankton (plants) and zooplankton (animals) impact the concentrations of dissolved gases like carbon dioxide (CO₂) and dissolved oxygen (DO) in marine environments. Through the process of photosynthesis, millions of phytoplankton in the ocean use the reactants carbon dioxide, water, and energy from the sun to produce sugar (glucose) and oxygen. Living organisms use the products of photosynthesis (glucose and oxygen) to respire and gain energy (ATP). As a result of respiration, water and carbon dioxide are released as byproducts. Photosynthesis and respiration remain in equilibrium as long as the populations of plants and animals remain in balance and conditions within the environment remain stable. A change in the abundance of organisms or the concentration of dissolved gases like carbon dioxide and oxygen will affect the chemistry in the ocean. This in turn affects the pH balance of seawater and impacts many biological processes. If the pH increases, it causes the water to become more “basic.” In other cases, if the pH decreases, then the water becomes more acidic. A drop of one pH unit corresponds to a 10-fold increase in the concentration of charged particles in the water, making it more acidic (Doney, 2006). The pH of seawater ranges from 8.0 to 8.3, meaning that the ocean is naturally somewhat basic. Changes in water chemistry of ocean ecosystems affects the health and survival of organisms over time.

Target audience: Grade 9-12 Biology, Marine Science, or Environmental Science

Time Frame: Initial set-up and data collection will take one lab period (one hour) and final data collection and conclusion will be one lab period (one hour). This experiment can be extended up to five days of observations.

Purpose: In this simulation, groups of students will record and observe the impact of plants (Elodea) and animals (brine shrimp) on carbon dioxide, dissolved oxygen and pH levels in a marine environment. They will review and discuss the processes of photosynthesis and respiration as vital biological processes and the impacts of changes in the processes on the health of the phytoplankton and zooplankton over time.

CA standards addressed: Life Science standards- 1f,1g, 6b , 6d. Earth Science Standard 7a. Investigation and Experimentation 1a, 1b, 1c, 1d, 1j, 1k,1m.

National Science Standards: NS.9-12.1 SCIENCE AS INQUIRY - Abilities necessary to do scientific inquiry investigations and understand scientific inquiryNS.9-12.6 PERSONAL AND SOCIAL PERSPECTIVES - Environmental qualityNS.9-12.7 HISTORY AND NATURE OF SCIENCE - Nature of scientific knowledge

TEACHER PAGES

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

pH and Carbon Dioxide The pH scale has values from (0 to 14) with 7 being neutral pH > 7 (alkaline) pH < 7 (acidic) pH of the ocean normally ranges from 8.1 to 8.4 at the surface pH is directly influenced by carbon dioxide levels

Animal Activity: Increases acidity (lower pH values) respiration decreases O₂ levels and increases CO₂ levels Plant Activity: Decreases acidity (higher pH values) increases O₂ and decreases CO₂ from the water through photosynthesis

Plankton and CO₂What impact do phytoplankton and zooplankton have on CO₂, DO and pH levels in marine environments?

A Partnership between California Current Ecosystem Long Term Ecological Research (CCE LTER) and Ocean Institute (OI) Beth Simmons, Education and Outreach Coordinator, CCE LTER, Scripps Institution of Oceanography, Christy Millsap, Teacher, Rancho Bernardo High

School, San Diego, California.

LESSON TWO

1

Page 2: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Materials:

TEACHER PAGES

Hypothesis: Brine shrimp (animals) and Elodea (plants) will change the levels of carbon dioxide (CO₂) and dissolved oxygen (DO) values within the water sample under light and dark environmental conditions which will result in the alteration of the levels of pH of the water.

Procedure:

1. Obtain 4 sample bottles-label them as follows:

1-brine shrimp, light

2- Elodea, light

3- brine shrimp, dark

4- Elodea, dark

2. Fill all four bottles with deionized water to equal volumes.

3. Take initial values for CO₂ , DO, pH and temperature in all four sample bottles and record in data table.

4. Place the brine shrimp in vials one and three, an Elodea sprig in vials two and four, then seal tightly with duct tape.

5. Carefully place vials one and two in a water bath under a light. (Note: The water bath can be an aquarium filled with room temperature water).

6. Carefully place vials three and four in a water bath in the dark. The water bath can be an aquarium covered with a trash bag to maintain a dark environment and filled with room temperature water.

7. Leave all the sample vials for 24 hours. (Note: Create graphs for each of the variables measured ahead of

time. There will be graphs needed for CO₂ versus time, DO versus time, and pH versus time.)

8. In class the next day, remove each sample from the water baths. Remove covers and record CO₂, DO, pH and temperature values for each sample bottle in your data table. (Note: If you are running the experiment for five consecutive days, then recap the vials immediately after data are taken. Otherwise, dispose of the contents properly and clean out all sample bottles.)

4 sample bottles with lids Aqueous Carbon Dioxide (CO₂) probe or chemical test kit for CO₂

Deionized water (DI) Dissolved Oxygen (DO) probe or chemical test kit for DO

Water bath (large aquarium or container) pH probe or chemical test kit

Ultraviolet light or other grow light Elodea sprigs (2 small sprigs per group)

Thermometer or temperature probe Brine shrimp (2 shrimp per group - if shrimp are small add more per group)

Heavy duty trash bag (to darken aquarium) Duct tape

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

LESSON TWO

2

Page 3: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

TEACHER PAGES

Brine shrimp (light) CO₂ DO Temperature pH

INITIAL Values

DAY 2 Values

DAY 3 Values

DAY 4 Values

FINAL Values

Elodea (light) CO₂ DO Temperature pH

INITIAL Values

DAY 2 Values

DAY 3 Values

DAY 4 Values

FINAL Values

Brine shrimp (dark) CO₂ DO Temperature pH

INITIAL Values

DAY 2 Values

DAY 3 Values

DAY 4 Values

FINAL Values

Elodea (dark) CO₂ DO Temperature pH

INITIAL Values

DAY 2 Values

DAY 3 Values

DAY 4 Values

FINAL Values

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

R

espi

ratio

nC₆H₁₂

O₆ +

6O₂

6CO₂

+

6H₂O

+

6A

TP

Glu

cose

+

O

xyge

n

Car

bon

Dio

xide

+

W

ater

+

En

ergy

Ph

otos

ynth

esis

6CO₂

+

6H₂O

C₆H₁₂

O₆

+

6O₂

Car

bon

Dio

xide

+

Wat

er

Ene

rgy

Glu

cose

+

O

xyge

n

DATA TABLE

3

Page 4: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

TEACHER PAGES

Analysis:

1. Create a graph comparing CO₂ concentrations over time and write a brief statement describing your findings. (Note: If you only completed one 24-hour period of observations, record your initial and final values over time.)

2. Create a graph comparing DO concentrations over time and write a brief statement describing your findings.

3. Create a graph comparing the pH values over time and write a brief statement describing your findings.

4. Why were the samples put in both light and dark environments? Explain.

5. Compare what happened to the levels of CO₂ over time in the dark and light brine shrimp vials and the dark and light Elodea vials.

6. Compare what happened to the levels of DO over time in the dark and light brine shrimp vials and the dark and light Elodea vials.

7. Compare the DO and CO₂ graphs to the pH graph. Explain your observations.

8. What is the relationship between the brine shrimp and respiration in the vials?

9. What is the relationship between the Elodea and photosynthesis in the vials?

10. What would happen to CO₂ and DO concentrations in the ocean if the number of phytoplankton (plants) decreased?

11. What would happen to the CO₂ and DO levels in the ocean if the number of animals increased?

12. If CO₂ levels became very high, what would happen to pH levels? What impact might this have on plants and animals living in marine environments?

Conclusion:

Formulate a thoughtful conclusion to this experiment written in paragraph form. The conclusion should consist of the following: a. What was the initial hypothesis of this research? b. Explain any possible errors that may have affected your experimental results. c. Explain your understanding of the exchange of dissolved gases within the ocean’s realm between plants and animals and the impact of these exchanges on the pH of the water. Evidence of your understanding should address the implications of an imbalanced pH in ocean water.

Diatoms

Copepod

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

Plankton and CO₂What impact do phytoplankton and zooplankton have on CO₂, DO and pH levels in marine environments?

A Partnership between California Current Ecosystem Long Term Ecological Research (CCE LTER) and Ocean Institute (OI) Beth Simmons, Education and Outreach Coordinator, CCE LTER, Scripps Institution of Oceanography, Christy Millsap, Teacher, Rancho Bernardo High

School, San Diego, California.

LESSON TWO

4

Page 5: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Possible Student Responses:

Analysis:

1. The student graph comparing CO₂ values over time should show the following trends:

• Elodea dark- no change to slight increase in CO2 level (due to lack of light for photosynthesis)

• Elodea light- large decrease in CO2 level (due to photosynthesis)

• Brine shrimp dark- increase in CO2 level (due to respiration)

• Brine shrimp light- increase in CO2 level (due to respiration)

2. The student graph comparing DO values over time should show the following trends:

• Elodea dark- no change to slight decrease in DO level (due to lack of light for photosynthesis)

• Elodea light- large increase in DO level (due to photosynthesis)

• Brine shrimp dark- decreased DO level (due to respiration)

• Brine shrimp light- decreased DO level (due to respiration)

3. The student graph comparing pH values over time should show the following trends::

• Elodea dark- no change to slight decrease in pH level (due to slightly increasing CO2).

• Elodea light- increase in pH level (due to decrease in CO2)

• Brine shrimp dark- decrease in pH level (due to increase in CO2)

• Brine shrimp light- decrease in pH level (due to increase in CO2)

4. Why were samples (plants and animals) put in the light and the dark? The samples were placed in the light and the dark environments to explore the impact of light on the levels of dissolved gases and pH. Light serves as an energy source and it is necessary for plants to undergo photosynthesis. The plant in the dark was the control in this experiment, showing that photosynthesis cannot take place without light. Therefore, the plant in the dark should have shown no change. In order for our experiment to remain valid, the brine shrimp also had to be placed in the same experimental conditions. Students should have observed very little difference between the two brine shrimp vials since they do not undergo photosynthesis.

5. Compare what happened to the CO2 levels over time in the dark and the light brine shrimp vials and the light and dark elodea vials. Over the observed time period, the measured CO2 values for both the light and dark brine shrimp vials should have been similar. Due to animal respiration, the CO2 levels should have increased in the vials as the shrimp gave off CO₂ as a by-product of respiration, and the rate of it is not impacted very much by light. However, the light and dark plant samples should have yielded different CO2 values. This is because plants in the light underwent photosynthesis causing a decrease in CO2 values. Remember that during photosynthesis, plants consume CO2 to make food (glucose). In contrast, the plant sample in the dark was unable to perform photosynthesis; therefore one would expect only a small increase (if any) in CO₂ as the plant respires.

TEACHER PAGES

5

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

Page 6: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Possible Student Responses Continued...

Analysis:

6. Compare what happened to the DO levels over time in the dark and light brine shrimp vials and the dark and light Elodea vials. The Elodea vial placed in the light should have shown increased DO values since photosynthesis occurred. Oxygen is a by-product of photosynthesis. The Elodea vial placed in the dark lacked light, so photosynthesis did not occur and DO levels would expect to decrease as respiration occurs. Since brine shrimp do not require light to respire, regardless of whether they were in light or dark vials the DO levels should have decreased over time.

7. Compare the DO and CO₂ graphs to the pH graph. Explain your observations. When all three graphs are compared, CO₂ and pH are inversely related. That means, as CO₂ levels increase, pH levels decrease and as CO₂ levels decrease, pH levels increase.

8. What is the relationship between the brine shrimp and the rate of respiration in the vials? The process of respiration requires oxygen and glucose. This process produces CO₂, water (H₂O) and energy (ATP). Brine shrimp are animals and all animals perform respiration to give their cells energy for growth and repair. DO in vials containing the brine shrimp decreased because it was “used up” and CO₂ which should have increased in this scenario was produced. Note: CO₂ reacts with the water to produce a weak acid which caused the water’s pH to increase.

9. What is the relationship between the Elodea and the rate of photosynthesis in the vials? The process of photosynthesis requires CO₂, energy (light), and water to produce oxygen, and glucose. The Elodea in light showed decreased CO₂ levels (it

was “used up”) and increased DO levels (it was “made” as a product). pH values change as a function of CO₂ values. So in other words, as CO₂ decreases, pH increases because less carbonic acid is produced (fewer free hydrogen ions). The Elodea in the dark lacked light for photosynthesis, so CO₂ levels should have increased and O₂ levels decreased as respiration occurred.

10. What would happen to CO₂ and DO levels in the ocean if the number of phytoplankton (plants) decreased? If the number of plants (photosynthetic organisms) in the ocean decreased, we would expect CO2 levels to increase and DO levels to decrease- due to the lack of photosynthesis occurring. If this continued we would see animals dying due to a lack of oxygen.

11. What would happen to the CO₂ and DO levels in the ocean if the number of animals increased? If the number of animals (organisms performing respiration) were to increase in the ocean, we would see decreasing DO values and increasing CO₂ values-due to the increase in respiration occurring.

12. If CO₂ levels became very high, what would happen to pH levels? What impact might this have on plants and animals living in marine environments? If the CO₂ levels became very high, pH levels would decrease (become more acidic). There is an optimal range of pH in the ocean of 7.8-8.4 the average being around 8.0. In lesson 5 we will explore the negative impact that decreasing pH can have on oceanic plants and animals. Students can hypothesize as to what may happen.

Conclusion:

Students should have similar conclusions to this experiment written in paragraph form. Their conclusions should consist of the following: a. Their initial hypothesis of the research b. Any possible errors that may have affected their experimental results c. Their understanding of the exchange of dissolved gases within the ocean’s realm between plants and animals, and the impact of these exchanges on the pH of the water. Evidence of their understanding should address the implications of an imbalanced pH in ocean water.

TEACHER PAGES

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

6

Page 7: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Vocabulary:

acidic: a pH value below 7.

ATP: An organic compound that contains large amounts of energy.

phytoplankton: Microscopic algae that live in the water and produce their own food through the process of photosynthesis. Collectively, phytoplankton are the foundation of the marine food web.

zooplankton: Drifting marine animals either invertebrates or larval fishes. These organisms are grazers, feeding on phytoplankton or predators, which consume other organisms.

photosynthesis: Chemical process by which plants convert light energy into chemical energy (glucose) 6CO₂ + 6H2O + light energy → C6H12O6 + 6O2

respiration: Chemical process through which animals convert chemical energy (glucose) into ATP to fuel cells C6H12O6 + 6O2 → 6CO₂ + 6H2O + energy(ATP).

pH: A common measure of how acidic or basic a solution may be.

dissolved oxygen: (DO) oxygen dissolved in water.

carbon dioxide: (CO₂) a chemical molecule composed of two oxygen atoms and one carbon atom; it is essential for many biochemical and living processes.

glucose: (C₆H₁₂O₆) a sugar that serves as the main source of energy for most living things.

Additional Resources and Notes:

1. Aqueous Dissolved Oxygen and pH probes are available through a. Pasco scientific- http://www.pasco.com/

2. DO, CO₂, and pH chemical test kits can be obtained through La Motte- http://www.lamotte.com/pages/edu/index.html

3. Test kits, probes and other water sampling supplies can be obtained through Wards- http://wardsci.com/category.asp_Q_c_E_915_A_Water+Testing+and+Sampling

4. Brine shrimp may be purchased from local fish and aquarium stores or can be hatched. Information and purchasing can be found at http://www.brineshrimpdirect.com/Hatching-Brine-Shrimp-Cysts-c169.html

5. Doney, Scott (2006) The Dangers of Ocean Acidification , Scientific American, pgs. 58 - 65.

TEACHER PAGES

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

7

Page 8: TEACHER PAGES Plankton and CO₂ - CCE LTERcce.lternet.edu/sites/default/files/L2_fnl_Plankton... · Introduction: Phytoplankton (plants) and zooplankton (animals) impact the concentrations

Extension: Besides acting as the first link in the food chain, phytoplankton are a very important part of ocean life. Phytoplankton play a role in acting as transporters of CO₂ from the atmosphere into the ocean. The direction of exchange (accumulation versus absorption) depends on how much is in excess and how much is absorbed by plankton. There is a constant exchange of CO₂ between the atmosphere and the oceans. Because of the large size of the ocean, and the occurrence of phytoplankton everywhere, the ocean is a sink for atmospheric carbon dioxide. What would happen if phytoplankton did not bring CO₂ from the atmosphere into the ocean?

Questions:

a. What might cause phytoplankton abundances to decrease?

b. If fewer phytoplankton existed, what might happen to atmospheric carbon dioxide?

c. What would the implications of decreased phytoplankton be for the ocean ecosystem?

Possible resources:

a. Satellite Images of Marine Phytoplankton Blooms http://geology.com/nasa/marine-phytoplankton.shtml#top

b. Hays, Graeme C., et. al. (2005) Climate Change and Marine Plankton, Trends in Ecology and Evolution, Vol. 20 No.6, pages 337 - 344.

c. Morello, Lauren (2010) Phytoplankton Population Drops 40 Percent Since 1950, Scientific American, July. http://www.scientificamerican.com/article.cfm?id=phytoplankton-population

TEACHER PAGES

Phytoplankton’s Influence?

Figure 1. Satellite image of chlorophyll a concentrations (which acts as a proxy for plankton biomass) from October 6, 2002 off the coast of California. Reds indicate high concentrations and blues indicate low concentrations.

Created by: Beth E. Simmons © 2009 (Revised 2011)Education & Outreach Coordinator CCE Long Term Ecological Research (LTER)Disclaimer: May be reproduced for educational purposes; cite appropriately

8

LESSON TWO