Salt Marsh - Scientific Study
How does the marsh change from the water’s edge to the high marsh?
Project O scientists laid a transect line from the water’s edge to the high marsh. In this portion of the virtual field trip, you will help them collect their data from photographs and videos, and then use your information to construct a profile of the marsh.
Marsh Elevation
We used a tool called an elevation stick to measure the slope of the marsh and how it changes along the transect line. In the slide show below, watch the video demonstrating how to use and read the elevation stick, then advance the slides to record elevation change for each meter along the transect. Calculate the cumulative elevation at each meter, with the meter 0 reading set as zero elevation.
To advance the slide show and collect data, click the forward arrow.
How to calculate elevation change from your elevation stick data.
Peat Depth
We used a tool called a peat pole to measure the depth of the peat layer along the transect line. In the slide show below, watch the video demonstrating how to use and read the peat pole, then advance the slides to record the peat depth every other meter along the transect. **Important: We measured the part of the pole that was sticking out. To calculate the peat depth, subtract the measured amount from one meter (100cm).**
To advance the slide show and collect data, click the forward arrow.
Quadrat Study: Marsh Plants
We placed quadrats every four meters along the transect line to monitor the composition and density of the plant community. View the slide show below, and record percent cover of marsh grass (Spartina) for each quadrat. If you are able to determine the identity of any additional species present, make a note of them.
To advance the slide show and collect data, click the forward arrow.
Water Quality
We looked along the transect line for areas with standing water where we would be able to measure water quality. We sampled at the following locations at low tide:
0m: Edge of the marsh, Poquonnock River water
11m: Salt Pan (the salt marsh equivalent of a tidepool)
20m: Salt Pan
31m: Tiny puddle. It was challenging to scoop enough water here to fill the hydrometer.
34m: Salt Pan. This salt pan was located approximately 10 meters from the transect line, even with the 34 meter mark. It was the largest and deepest salt pan that we sampled.
Water Temperature, Salinity, pH and Oxygen Levels
At each of these five locations, we measured water temperature, salinity, pH, and oxygen levels. Each slide show begins with a video explaining how the measurement was made. Watch the video, and then advance the slides to record the water quality results based on the photos or videos that follow.
Water Temperature
To advance the slide show and collect data, click the forward arrow.
Salinity
To advance the slide show and collect data, click the forward arrow.
pH
To advance the slide show and collect data, click the forward arrow.
Oxygen Levels
To advance the slide show and collect data, click the forward arrow.
Assignment: Construct a visual profile of the marsh based on quantitative data
Use a large sheet of paper (or a graphics program) to construct a visual profile of the marsh.
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Draw the x-axis approximately ¼ of the way down from the TOP of your piece of paper.
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Label the x-axis from zero to 44 meters - this represents the transect. Make sure the scale of the x-axis is reasonable (not too small) given the size of your paper.
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Draw the Y- axis. Add the highest elevation reading to the deepest peat depth - these values should be near the maximum and minimum of your y-axis respectively. The x-axis should cross the y-axis at zero.
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Plot the marsh elevation above the x-axis. Elevation readings are typically positive.
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Plot the peat depth below the x-axis. The peat depth readings should be negative.
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Add water quality and vegetation data as appropriate along your visual profile.
Assignment: Answer the following discussion questions based on your scientific data and your visual profile
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How does the physical environment of the marsh vary (if at all) from the low marsh to the high marsh?
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How does the biological environment of the marsh vary (if at all) from the low marsh to the high marsh?
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Based on your visual profile, how might a 5cm rise in sea level affect this marsh? Explain your answer.