• This lesson plan is also available in PDF Click here to download
• This activity should follow lessons on life in the inter-tidal zone and estuary food webs.
• Created for 4th-6th grade
• Supplements any of the life science kits, such as: Environments or Structures of Life, or as a supplement for the Earth Science kit: Water
• Activity should follow a lesson on life in the inter-tidal zone and estuary food webs
• Takes approximately 8 to 10+ class sessions (35-45 minutes)
• Uses science notebooks http://www.sciencenotebooks.org/

• Humans make decisions that affect the live of estuary organisms, maybe inadvertently.
• A model may be used to represent systems and processes.

• How do excess nutrients found in surface water affect an estuary?
• How can models be used to investigate phenomena?

• What people do on land has little or no effect on organisms in estuaries.
• Fertilizer is good for all plants. The more the better.
• Fish do not need oxygen.
• Students may be unfamiliar with the use of models to study phenomena.

• Notebooking
• Modeling a system
• Inquiry boards
• Whole class investigation

• Investigation Assessment Sheet.
  http://www.padillabay.gov/lessons/Investi-student.pdf
• Notebooks containing Inquiry Board Process
• Written "Recommendations to the Public"

This lesson focuses on the Estuary System.

The important structures are:

• salt water
• Fresh water entering estuaries from surface water.
• Land near rivers, lakes and salt water.
• Nutrients: from detritus, chemical plant fertilizers (NPK), cow manure, pet feces, leaky septic systems, sewage treatment plants.
• Bacteria: including fecal coliform
• Producers: eelgrass, macro algae, phytoplankton.
• Consumers: Estuary animals including but not limited to worms, snails, bivalves, crustaceans, fish, birds, mammals.

Matter and Energy Transfers :

• Producers transfer light from the sun into food energy (chemical).
• When plants and animals die, they decompose. Small bits of decomposing organic matter (detritus) provide chemical food energy to many estuary animals.
• Detritus is also a source of nutrients for plants.
• Detritus, carried by water, collects in estuaries where there is reduced kinetic energy (backwaters protected from wind, waves and tides).
• Wind, waves and tidal currents carry detritus and also restrict the plants and animals.

Forces acting on the system:

• Gravity pulls water downhill and underground.
• Gravity acts on solids suspended in water to cause sedimentation.
• Moving water and sediments act on plants and animals limiting where they can live.

• Science Notebooks http://www.sciencenotebooks.org/
• Aquarium Setup Sheet http://www.padillabay.gov/lessons/AquarSetup.pdf
• Scientific Collection Permit is required from WA Department of Fish and Wildlife (WDFW). Call WDFW License Division at 360-902-2473.
• Inquiry Board student handout http://www.padillabay.gov/lessons/InquiryBoards.pdf
• 2 ten gallon aquariums or alternative
• Testing equipment for measuring dissolved oxygen, temperature, salinity and pH. Equipment may be borrowed from a County Conservation District, wastewater treatment plant or other municipal agency that deals with water quality, or purchased from various suppliers including:
  Hach: www.hach.com
  Fisher Scientific: www.fishersci.com
  Carolina Biologist: www.carolina.com
  VWR Scientific Products: www.vwrsp.com
  
• About one-half cup of powdered houseplant food.

1. Ask students to write in their notebooks what they know about plant nutrients and fertilizers and how these things might interact with estuary systems. Then students draw a "line of learning" under what they have written.
   
   
2. Discuss how plant nutrients naturally collect in estuaries from surface water and marine sources.
   
   
3. Discuss other human sources of nutrients such as chemical fertilizers used to grow flowers and grass. When used or dispersed outdoors, these things may get into surface water and find their way to an estuary.
   
   
4. List other sources such as animal manure, pet feces, leaky septic systems and sewage treatment plants.
   
   
5. Students add additional ideas about plant nutrients to their notebooks under their line of learning.
   
   
   
6. Ask students "How can models be used to investigate phenomena?" Discuss the advantages of being able to:
   • control variables
   • work on a scale that is smaller than the real estuary and is therefore easier to cause and see results, and
   • avoid harming the environment
     
     
7. If possible, visit a local estuary. Collect organisms and water as described in the Aquarium Set-up Sheet. http://www.padillabay.gov/lessons/AquarSetup.pdf
   
   
8. A Scientific Collection Permit is required from WA Department of Fish and Wildlife (WDFW). Call WDFW License Division at 360-902-2473.
   
   
9. Set up two model aquaria in the classroom.
   
   
10. Allow the aquarium to sit for a couple of days for the temperature to normalize.
    
    
11. Meanwhile, use the Inquiry Board strategy http://www.padillabay.gov/lessons/InquiryBoards.pdf to guide students through designing the investigation.
    • A sample investigative question would be "How do excess nutrients from runoff affect an estuary?"
    • The changed variable could be the addition of chemical fertilizer to one of the aquariums.
    • The measured variable, dissolved oxygen.
      
      
12. Ask students to predict how an increase in nutrients (fertilizer) will affect levels of DO in the aquarium. Explain that a prediction must involve reasoning based on some knowledge or evidence, otherwise it is not a prediction, it is a guess. Students record their predictions and reasoning in their science notebooks.
    
    
13. To begin the investigation, take DO, temperature, salinity and pH measurements for a few days before introducing the changed variable. When you no longer see fluctuations in your data add plant food to one aquarium, one tablespoon for each gallon of water. Label the aquaria.
    
    
14. Record measurements for several days. If the measurements in both aquariums are essentially the same, add another tablespoon of fertilizer per gallon to the same aquarium.
    
    
15. Ask students to decide if the evidence from their investigation confirms or refutes their predictions. Record conclusions in Inquiry Board student handout or science notebooks.
    
    
16. Evaluate the use of models:
    • Ask students to identify or describe the similarities and/or differences between the aquaria and a real estuary.
    • Ask students to describe reasons for using a model to investigate phenomena (e.g. processes that happen very slowly or quickly; things that are too small or too large for direct observation; phenomenon that cannot be controlled or are potentially dangerous).
      
      
17. The expected results are that after adding the fertilizer the plants will at first increase their growth which will increase the amount of oxygen in the water. However, as the water gets fouled with algae and more plants die and rot, the bacterial action will increase, thereby consuming dissolved oxygen. In a real estuary, reduced oxygen causes fish kills.
    

    Search the internet for local stories or try these:
    
    Hood Canal fish suffocate-Seattle PI
    http://seattlepi.nwsource.com/local/285777_fishkill21.html

    Hood Canal Dissolved Oxygen Program
    http://www.hoodcanal.washington.edu/

    Marine Water Quality Monitoring
    http://www.ecy.wa.gov/programs/eap/mar_wat/mwm_intr.html

18. Use the Investigation Assessment Sheet and evidence from the (inquiry board) conclusions written in student notebooks to assess student learning.
    
    
19. Return to the essential questions:
    1. How do excess nutrients found in surface water affect an estuary?
    2. How can models be used to investigate phenomena?
       
       
20. Ask students to write "Recommendation to Citizens" based on the results of their investigation. Include a rationale.
    
    
21. Have students fill out the Investigation Assessment Sheet http://www.padillabay.gov/lessons/Investi-student.pdf
    
22. As a follow-up, continue the investigation by adding filter feeders such as clams, oysters, or barnacles to see if they can remove algae, detritus and bacteria from the water, thereby improving oxygen levels. Make sure there's enough dissolved oxygen before adding any animals.