Prince William's Oily Mess - A Story of Recovery

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a. Read Intro | b. Learn the Organisms | c. State Predictions!
a. Observe Mearns Rock | b. Record Data
a. Plot Data | b. View Example Graph
a. Interpret Data & Write Report | b. Share What You Have Learned
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Graphing Changes in Marine Life Abundance

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STEP 2b: Record Your Data

Before you begin collecting data, you need to gather the resources necessary to record your data from the quadrat photos. You should do the following:

arrow Print the Data Table

arrow Print the Percent Cover Chart

arrow Review the Tips for Collecting Data


arrow Data Table - Open and print out the data table (pdf, 47Kb).

Data Table Thumbnail   You'll use it to record your estimates of percent cover of Fucus, mussels, and barnacles in the Mearns Rock quadrats from 1990 to 2004. You will assume that the percent cover of each organism was 0 in 1989. To help you "calibrate" your estimates, we've included our estimates of percent cover for each organism in 1990.


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arrowPercent Cover Chart - Open and print the percent cover chart (pdf, 58Kb).

You’ll use this chart as an aid for estimating the percent cover of a particular form of marine life in the quadrat you are observing. Think of the black areas in the chart as representing one of the three marine life forms you saw earlier in the field guide.

percent chart thumbnail

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arrow Tips for Collecting Data

Because the Mearns Rock quadrat photos were taken at different times of day and under different weather and light conditions, they vary in their color and clarity.

Watch for four color ranges to identify the marine life:

    Gray areas tend to be bare rock.
    Black areas are often mussels.
              Areas that range from green to gold to brown are often Fucus gardneri (rockweed or popweed). Young Fucus plants are more green in color, mature plants are more brown.
    White or light gray regions tend to be barnacles.


Establish Observation Criteria

As you look through the photos, you will note that algae or seaweed sometimes covers much of the rock, possibly hiding barnacles and mussels from view. Before making your estimates, first establish the criteria that you'll follow. For example, consider basing your observations on "what's visible" rather than on your best guess of what might be living underneath something else. Also, consider the intense competition for space that exists among marine life forms in the intertidal region. For example, if sea otters clear mussels off a section of the rock, that opens space for barnacles, Fucus, or other organisms to "move in" to that space. You'll see several examples in these photos.

Time to Get Started!

You are now ready to open the series of high-resolution photos of the same quadrat of Mearns Rock, taken each year from 1990 to 2004. As you examine each quadrat photo, you will estimate how much of the quadrat Fucus occupies (as a percent of the total area), how much of the quadrat mussels occupy, and how much of it barnacles occupy. Record your estimates in the data table you printed out earlier. Now, go back to the quadrat photos in Step 2a to start recording your data!

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next page Proceed to Step 3a: Plot Your Data

Revised March 25, 2008 | Questions, Comments? Contact Us | Report Error | Disclaimer | About the Site | User Survey
Web Site Owner: National Ocean Service | National Oceanic and Atmospheric Administration | Department of Commerce | USA.gov
http://oceanservice.noaa.gov/education/stories/oilymess/working_record.html