Week 5: Monitoring Invasive Species

Getting to Know Querying in ArcGIS

Learn to create and execute GIS database queries to investigate the spread of zebra mussels.

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Launch ArcGIS, Open the Invasive Species Project File, and Add a New Layer


  • Launch ArcGIS by double-clicking its icon on your desktop or by clicking its icon in the Start > All Programs > ArcGIS > ArcMap.
  • 5201 Start Program
  • A startup window opens and asks if you want to start from an empty interface or a past project. Choose the New Empty Interface radio button.
  • 5203 ArcMap Start Screen
  • On the tool bar usually at the top of the interface, click on the File > Open, navigate to your C:\\EyesInTheSky2\Week5 folder and select the file inv_spc.mxd. Then click Open.
  • Add a new layer to show the sightings of the invasive Zebra Mussels. Click the Add Data 5205 Add Data Button button. Navigate to the invasive_speciesAM folder. Click once on zebra_mussel.shp to select it. Then click Add.
  • zebra_mussel should now be the top layer on your map. Notice that the layer is automatically turned on when it is added.
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Zebra mussels; Dreissenna Polymorpha

Zebra mussels are small shellfish named for the striped color of their shells. They typically attach to objects by threads on their shells. The zebra mussel is native to the Black, Caspian, and Azoz Seas. They were first described in Europe, by Pallas, in 1769.

small zebra mussel image Zebra Mussel

Zebra mussels were first discovered in the Great Lakes of North America in 1988. It is likely that their introduction was due to a ballast exchange from a cargo ship. By 1990 they had spread rapidly to all of the Great Lakes. Soon thereafter they escaped to the Illinois and Hudson Rivers, eventually moving into the Mississippi River system. By 2008, Zebra Mussels had spread across the United States, all the way to California.

Zebra mussels are a significant invader because they can spread both in and out of the water. In their freshwater habitat they can disperse in all life stages. They are prolific biofouling agents and therefore have profound effects on water supply pipes, including nuclear power plant cooling intake pipes. Not only do they damage man made structures, they are disruptive to entire food webs. Zebra mussels primarily consume phytoplankton. Additionally, they consume other suspended materials in the water column. Consequently, areas with dense invasions of zebra mussels have unusually transparent water. In fact, during the invasion of zebra mussels in Saginaw Bay, Michigan the sampling areas experienced a 60-70% reduction in Chlorophyll –a concentrations.

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Adjust the Layers and Zoom in to the Zebra Mussel layer

  • Turn on the US States and US Rivers layers.
  • Right click on US Rivers in the Table of Contents and click on Zoom To Layer. 5209 Map Zoom to Rivers
  • Right click the zebra_mussel layer in order to zoom to the current extent of the zebra mussel invasion.
    The map shows the extent of the zebra mussel invasion in the United States as of 2008.

    5209 Map Zoom to Mussels
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Find A Feature By Its Attributes

The Find tool 5211 Find Button is a quick way to locate a feature. However, this type of search works best if you know how to spell, and capitalize, what you are looking for.
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Find the zebra mussels in Ohio.

  • Right-click on the zebra mussel label in the Table of Contents. Then select Open Attribute Table. Spend some time looking through the fields and data records that are in the table. Use the scroll bars to move up and down and across the table. Look carefully at the State abbreviations.
  • Close the Attribute Table.
  • Click on the Find 5211 Find Button tool. When the Find window opens, move it so you can see the both the map and the window.
  • In the window that pops up, on the Features tab, type in the name of the abbreviation for the State of Ohio, OH in the Find: box..
  • Select zebra_mussel from the "In:" list of Layers to Search. Click Find to search for the features in the layer that have "OH" as an attribute.
  • In the results section of the Find window, 198 records have been located. The first result is highlighted. Click a row to make the record flash. Right click to select the zebra mussel record and highlight it in blue on the map.
  • Click on other records in the list of results and watch the blue dot move around on the map.
  • To select a group of records, hold the shift key down while clicking on results in the Find window.
  • When you are done, click the Clear Selection button (in the toolbar area) 5220 Clear Selected Button to clear all selections from the map.
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Find the US State of Ohio.

  • In the Find window, select US States in the list of Layers to Search. Click Find to search for the features in the layer that have 'Ohio' as an attribute. Click Select to highlight the 'Ohio' record.

  • Close the find window and you should see Ohio centered in your map view.
    5224 Ohio Centered
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Question a Database with Select by Attribute

Another way to find features, especially for larger or more complex searches is to Select by Attribute (This is the same concept as the Database Query in AEJEE).

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Find all the zebra mussels sighted in the year 1988.

  • Click the Selection > Select by Attributes. A new window opens. Move it where you can see both the Select by Attributes window and the map.
  • In the Select by Attributes window double click the field YEAR then click the "equals" sign. Finally choose the Get Unique Value button and double click 1988. You can also type in this equation ("Year"=1988) into the box in the middle window ArcGIS. Click OK and five records should be selected on the map. 1988 by clicking once on it. You can also type in this equation ("YEAR" = '1988') into the box in the middle of the window. Click Apply. Five records are selected on the map.
    To see these records in the attribute table, right click on the layer name in the Table of Contents and choose Selection > Open Table Showing Selected Features.
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    Find all the zebra mussel records from New York, NY.

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    Put these two queries together to find all the zebra mussel records in the state of New York in the year 2005.

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    Set up a query to find a set of zebra mussels within the date range between 1997 and 2000.

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    See how the zebra mussel invasion progressed over time

    In the Select by Attributes window, select groups of YEARS with the less than operator. Movie Icon

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    Create and Explore More Database Queries

    Practice querying using combinations of set (, =) and Boolean operators (And, Or, Not, etc.)

    Try the following:

    1. Use the zebra mussel layer to answer the question:
      Where are the zebra mussels that are in Ashtabula County AND Ohio?
    2. Substitute OR in the equation above with the zebra mussel layer:
    3. In the US Rivers layer, try this equation that combines both set and Boolean algebra.
      ("SYSTEM" = 'Mississippi') and ("LENGTHCOMP" >= 1361.4323989)
      What question does this query answer?
    4. The US States layer has interesting data to practice with.
      What happens when you enter this expression?
      not ("STATENAME" = 'Texas')
    5. Try this equation with the US States layer:
      ("POPULATION" >= 1211537) and ("MEDIANAGE" What question does this query answer?
    6. The wildcard symbol % combined with the expression LIKE allows you to set up a query that is a bit more open ended. Enter this equation in the Select by Attributes in the US States layer:
      ("STATENAME" like 'A%')
      What result do you get and why?
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    Build Your Own Database Query and Take a Screenshot

    Design and execute a query of interest to you or that you might use in your teaching. Here are a few suggestions.

    Once you have built and executed a query, take a screenshot of the map and the Select by Attribute window. In your discussion group, post the question you asked, the equation you used, and the result of your query along with the screenshot. This is the screenshot that is needed for your required weekly activity.

    Follow the instructions below to make a screen shot:

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    Explore More If You Have Time

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    Movies on this Page

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    How to download movies

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    Flash Video Versions

    Download these versions to play on your computer. You'll need an appropriate movie player to view the file, such as Flash Player, Real Player (Mac / Win), or Adobe Media Player.

    Movie Icon Adding Layers ArcGIS

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    iPod Versions

    Download these version to play on your iPod or iPhone.

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