EarthLabs > Fisheries > Lab 1: Plenty of Fish in the Sea? > 1B: Exploring Biodiversity Maps

Plenty of Fish in the Sea?

Part B: Exploring Biodiversity Maps

People have been catching fish from the ocean for thousands of years, but it was only recently (in the 1950's) that anyone started keeping records of the numbers and types of fish they caught. In 2005, scientists gathered as much of this data as they could and used it to produce global maps of the locations of fish populations over time. These maps make it possible to track which areas of the ocean are in the greatest danger of exhausting their fisheries. The maps you will study in this part of the investigation are species density maps. This means that the data you are looking at is the total number of species per square kilometer (or mile) of ocean, a measure of marine biodiversity (variety of life in the oceans).

ImageJ is a public domain, Java-based image processing program. If this software is available on your school computers, continue with the instructions for this activity using Image J. If ImageJ is not available on your school computers, continue with the instructions for this activity without ImageJ.

  1. Click on the thumbnail image below of the global marine biodiversity map for the 1960s. Familiarize yourself with the color codes and identify one place on the map where species density is especially high and one where species density is particularly low. Note that white space indicates an area for which data was not available.

    The species density index is the number of species scientists expect to find for every 1000 fishing hooks used in a given area of ocean. The species density index values shown on each map are averages of all data collected during the given decade. For example, the 1960s map shows the average of species density values measured for the years 1960-1969.

    1960s
    1970s
    1980s
    1990s


  2. Create a new folder on your computer's desktop. Download the 1960s map and save the image in this new folder, keeping the default image name.

  3. Click on the thumbnail to open the image of the 1970s map. Are there any obvious differences between this map and the 1960s map?

  4. Download the global marine biodiversity maps for the 1970s, 1980s, and 1990s, again keeping the default image names and saving them in the new folder you created for this activity.

  5. Open the four biodiversity map images as a chronological sequence using ImageJ.
    1. From ImageJ's menu bar, choose File > Import > Image Sequence... and navigate to the folder where you stored the downloaded biodiversity maps. Select the "1960sbiodiversity" image and click Open.
    2. A Sequence Options dialog box will appear. In the box next to Number of Images: enter the number "4". In the box next to File Name Contains: type in the word "biodiversity". Leave all other boxes with their default values and click Okay.
    3. NOTE: This step puts all four images into a single window named Stack. You can flip between the images by dragging the slider button along the bottom of the stack window, or by pressing the greater than ">" or less than "<" keys on your keyboard.


  6. Look at the color scale below the map to figure out where the greatest concentrations of fish are.
    • Use the < and > keys to flip through the stack of images to examine them one at a time.

  7. Save your image stack as a TIFF file.

  8. Make a movie from your stacked images.
    1. From ImageJ's menu bar, choose Image > Stacks > Animation Options....
    2. In the box next to Speed (0.1-100 fps): enter the number "2". Check the box next to Start Animation. Make sure the box next to Loop Back and Forth is not checked so that the animation only runs forward in time. Click Okay.

  9. Allow your movie to loop through several cycles as you observe how the map changes over time.


  10. To stop the movie, select Image > Stacks > Stop Animation from ImageJ's menu bar.




  1. Click on one of the thumbnail images below. Familiarize yourself with the color codes and identify one place on the map where species density is especially high and one where species density is particularly low. Note that white space indicates an area for which data was not available.

    The species density index is the number of species scientists expect to find for every 1000 fishing hooks used in a given area of ocean. The species density index values shown on each map are averages of all data collected during the given decade. For example, the 1960s map shows the average of species density values measured for the years 1960-1969.

    1960s
    1970s
    1980s
    1990s


  2. Watch the animation below of global marine biodiversity from the 1960s through the 1990s.
    • NOTE: the decade represented by each frame of the animation is shown in the upper left corner.
    • If you would like to view any individual frame of the animation, click on the appropriate thumbnail image above.






Stop and Think

1: How does the overall color of the map change over time? What does this imply about the overall diversity of fish in the sea?

2: Can you identify any "hotspots" (areas with larger concentrations of species diversity than the surrounding ocean)? Do they persist over time?


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