Grade Levels

4 - 12

Objectives

    Squish . squish . . . squish . . . squish . . . in a marsh. Your students walk on water and on land at the same time. Marsh habitats reflect this in-betweenness. In this activity, students look for the indicators of transition from the aquatic to the terrestrial.

    Students will investigate natural organization of a wetland and the interrelationships between the wetland and the surrounding environment by:

• planning a study;
• observing wetlands;
• inferring cause and effect relationships.

Standards of Learning

Science:

• Grade Four: 4.1, 4.5, 4.8
• Grade Five: 5.1, 5.5
• Grade Six: 6.1, 6.2, 6.9, 6.11
• Life Science: LS.1, LS.4, LS.5, LS.7, LS.8, LS.9, LS.10, LS.11, LS.12
• Earth Science: ES.1, ES.9
• Biology: BIO.1, BIO.9

Background

    Along the fringes of the Chesapeake Bay, its tributaries and up to the farthest reaches of its headwaters, are habitats essential to the Bay's survival--habitats that are part land and part water--wetlands.

    By definition, wetlands are areas that have soil saturated or covered with water for a period of time, and have plants that are adapted to living at least part of the time, in water. The most familiar wetlands are fresh- or saltwater marshes, wooded swamps, and bogs.

    Wetlands have many values. The stems and leaves of wetland plants trap eroded soil washing from the land and absorb the energy of storm waters. Nutrients that might over enrich the waterways are trapped and used by wetland plants for growth. When these plants die, they enrich the waterways with decaying matter called detritus, a vital food source for microscopic organisms near the base of the food chain. Countless aquatic animals find food and shelter in wetlands including juveniles of many commercially valuable fishes, such as striped bass, and crustaceans, such as blue crabs. An array of wading birds, song birds, waterfowl and birds of prey are attracted to wetlands for food and nest sites.

    Historically, wetlands have been maligned by man. Blamed as sources of insect pests, they were ditched and drained. Often close to dredging operations, they were covered with dredge spoil. Considered inconvenient barriers between humans and waterways, they were dredged in some places and filled in others for the construction of marinas and waterfront homes.

    Steadily over the past few decades, scientific evidence of the benefits of wetlands has mounted and recently laws have been enacted for their protection. However, the future of wetlands rests in the hands of today's youth.

Materials

• "wettable" footwear
• Wetlands Observation Sheets (1 per team)
• Wetlands Investigation Guides (1 per team)
• clipboards
• pencils
• insect repellent
• trowel

Resources

Silberhorn, G. 1982.

Common Plants of the Mid Atlantic Coast: A Field Guide. Johns Hopkins Press, Baltimore.

Procedure

Before the Trip:

1. Study the park information in this guide and visit the park to identify the best location for exploration.

2. Divide the class into teams of three to five students.

3. Give each team a copy of the accompanying Wetlands Investigation Guide. Ask if anyone happens to already know the answers to any of the questions. After obtaining an answer to one of the questions, ask the student how he/she knows that answer is true. Do not tell the student whether he or she is correct, but thank the student for the information and point out that part of a scientist's concept of "true facts" is that they may be verified by anyone who takes the time and trouble to make careful observations. Explain that the class will be visiting a wetland to make watchful observations which will enable them to infer answers to the questions posed in the Investigation Guide.

4. Give each team a copy of the Wetlands Observation Sheet. Point out that the 12 observation suggestions already listed should be helpful in developing inferences about wetlands, but that the students will need to make other observations also. Allow time for the teams to consider what kinds of additional observations may be needed to address all of the investigation questions, and to add these to the back of the observation sheet. Collect all of the Investigation Guides and completed Observation Sheets. Check the students' observation lists to make sure that everything they have added may actually be seen, felt, smelled, or heard.

5. Review the field trip plans.

At the Park:

1. Return to each team its copy of the Wetland Observation Sheet, but not the Investigation Guides.

2. Explain the importance of approaching the wetland area quietly in order to improve chances of seeing wildlife. Lead the class to the edge of the wetland. Pause for a few minutes of silent observation.

3. Remind students that they might not observe wetland features in the order listed on the Observation Sheet and that they may record any observations of interest, whether or not they are suggested on the sheet. Lead them into the wetland. In some areas, this will be along a boardwalk. In others, where the footing is sound, it will be directly onto the wetland. The teams make as many observations possible in 30 minutes. Lead the class to key areas of the wetland (particularly where the elevation, and hence, the flora, changes dramatically) and encourage them to use all of their senses. Dig (and replace after observation) small plugs of soil so teams may observe below surface conditions. If possible, make a photographic record of the areas/items observed.

4. When students have completed their observations, lead them out of the wetland to an assembly area suitable for a group discussion about their observations. Compare the teams' observations.

   • Did everyone see everything the same way?
   • Which observations does the group think will be most useful for suggesting possible answers to the investigation questions?
   
   

5. If you have the knowledge (or access to a knowledgeable guide), tour the wetland with commentary on the value of wetlands.

Follow-up:

1. Return to each team its Investigation Guide. The teams consult their list of observations and identify those which should be helpful in responding to each of the questions on the Investigation Guide. On the guide sheet after each of the investigation questions, students note the numbers of their observations which may lead to an answer, and, within the right hand column, state what they believe to be a likely answer to the question, based on those observations. Copy the example provided in the box below on the blackboard.

   
   

   Example:
   Investigation Question	Relevant Observations	Inference (Possible Answer)
   1. Where does upland end and the wetland begin?	No. 3 No. 4 No. 8 No. 11	The borderline between upland and wetland separates drier soil where bushes and trees grow from wetter mud where mostly grasslike plants grow.

   
   

   Work through the first two questions as a class, then allow the teams time to do the remaining seven questions. Some observations will have bearing on several questions, some may have nothing to do with any of the questions.

2. The teams share and explain their inferences. As you moderate the discussion, recognize inferences which lead students towards the ideas suggested in the teachers' version of the Investigation Guide, but also pursue discussion of other logical and interesting inferences that your students have made.

3. Discuss the following:

   Thinking of the conditions in which wetlands can exist, what are some human activities that might destroy them?

   • Damming the waterway downstream might flood wetlands.
   • Damming the waterway upstream may dry them up.
   • Water drawn from the waterway for irrigation or a draw-down in the water table by nearby wells could dry up a wetland.
   • Cutting a ditch across a wetland may drain it.
   • Pushing dirt onto the wetland, as for preparing a construction site, would obviously destroy it.
   • Dramatically disturbing the soil on the nearby uplands might result in enough sediment to be washed onto the wetland to fill it in.
   • Repeated wakes from excess boat traffic could destroy a marsh by erosion.
   • Potentially, global warming could raise sea level enough to destroy coastal wetlands by flooding.

   How does the wetland help life forms in the adjacent waterway by trapping sediments?

   • Suspended particles intercept light essential to aquatic plant life.
   • Suspended particles clog gills of fishes and other estuarine organisms.
   • Sediments cover and smother oysters and other stationary bottom dwellers.

   How do wetlands help life in the estuary by removing excess nutrients?

   • Excess nutrients, such as nitrogen and phosphorous, cause sudden population explosions of algae. The algae block light necessary for beneficial plant life and deplete oxygen in the water, especially when they die and are being decomposed.

   Where might the excess nutrients come from?

   • Agricultural runoff from fertilizers and live stock wastes.
   • Human wastes from inadequate or failing sewage treatment systems.
   • Lawn fertilizers.
   • Possibly acid rain.

Extensions

1. Investigate ways to verify the inferences made.

   • Discuss the scientific method. The teams develop one inference into a testable statement design and conduct the research.
   • Investigate scientists' views on certain topics and the basis of those views.
   
   

2. Students map the distribution of plants and animals observed.

3. Visit the same area at another time of year. Compare both sets of observations and develop inferences about seasonal changes.

4. Students design an advertising campaign to inform others about wetland values and issues.

5. Students find and share media reports about wetlands.

6. Students research current wetland legislation and express their written opinions to appropriate politicians. Call 1-800-CRIS (Chesapeake Bay Hotline) for information on current issues.

Where in the Parks

When

Time Required at the Park:

Allow up to 1 hour for observations and discussion, plus time to walk to and from wetland area. Any daylight hours are suitable. Most tidal wetland areas may be best observed during low tide.

Time of Year:

Any time of year is suitable. In spring and summer, new green plants are emerging or at peak growth. In fall, some will be in flower. By winter, most plants will be brown and dying back.

Variations

Eliminate use of teams and Observation Sheets. Discuss key wetland features before the field trip and guide class observation of these features, using the Teacher's Version of the Investigation Guide. Consider questions individually, seeking out pertinent observations. Take pictures of these features and your observers, collect representative leaves, and make an informative classroom display.

• Students design quantitative techniques to investigate a wetland (e.g. determine elevation of wetland's upper limit and water depth of lower limit; identify and list specific plants; catch and identify animals; compare soil particle size and organic content with samples from different areas of the wetland and the upland).
• Design and conduct an "EQ" survey (environmental quotient) to assess public knowledge of wetlands and their values.

Instructions: When you click on the following links, a worksheet will appear in a separate window. If you want a printed copy of the worksheet, use your print command while the window is open and highlighted. Click on the close box in the worksheet window to return back to this lesson plan.

• Wetlands Observation Sheet
  
• Wetlands Investigation Guide
  
• Wetlands Investigation Guide - Teachers' Version