Eyes in the Sky II > GIT Web Course > Module 2 > Week 5 > Getting to Know Querying in GIS > Getting to Know Querying in My World

Week 5: Monitoring Invasive Species

Week 5: Monitoring Invasive Species

Getting to Know Querying in My World

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

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

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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

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Find A Feature By Its Attributes

The Find tool 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 first zebra mussels in record from Ohio.

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Use the Legend to find the U.S. State of Ohio

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Question a Database with the Analyze Mode

The best way to find features, especially for larger or more complex searches is to Query the database in the table of the layer. In My World GIS this is done in the Analyze mode.
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Find all the zebra mussels sighted in the year 1988

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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

  • Execute the first query. In Analyze mode, Select... > By Value .
  • Select Records from: Zebra Mussel, Whose YEAR is before 1989 CE and is On or After 1987 CE. Name the Result: Zebra Mussel 1987 - 88. Click OK. Continue moving through the years to follow the invasion.
    The statement, Select Records from: Zebra Mussel, Whose YEAR is before 1989 CE and is On or After 1987 CE, produces 5 results highlighted on the map.
    73 anlyse window
    74 5 records on map
  • Leave the "Is On or After" setting the same, 1987, and change just the "Is Before" statement to see how the invasion changed over time.
  • How many zebra mussels had been documented by the end of 1988? 1990? 1999?
    The equation (YEAR < 1989) shows that 5 zebra mussels were documented by the end of 1988.
    The statement Whose: YEAR is Before 1990 and On or after 1987, shows that 20 zebra mussels were documented by the end of 1989.
    The equation YEAR is Before 2000 and On or After 1987 shows that 2354 zebra mussels were documented by the end of 1999.
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    Create and Explore More Database Queries

    Practice querying using combinations of set and Boolean operators, such as <, >, =, 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?
      The equation is: Whose COUNTY is Ashtabula AND Whose STATE is OH
      The result of this query is 3 records.
    2. Substitute OR for AND in the equation above with the zebra mussel layer:
      The equation is: Whose COUNTY is Ashtabula OR Whose STATE is OH
      This query yields 95 records because it gives you BOTH records that are either in the county of Ashtabula or that are in the State of Ohio. The expression "OR" is more inclusive than the operator "AND".
    3. In the U.S. Rivers layer, try this equation that combines both set and Boolean algebra.
      Whose SYSTEM is Mississippi AND Whose LENGTHCOMP Greater than or Equal to 1361.4323989
      What question does this query answer?
      What rivers in the Mississippi River system have a length greater than or equal to 1361.43?
      Six rivers are selected.
    4. The U.S. States layer has interesting data to practice with.
      What happens when you enter this expression?
      Select Records from U.S. States, Whose Name Is Not Texas.
      The query shows all the U.S. States other than Texas. The result is listed as 50 States because the District of Columbia is included as a state.
    5. Try this equation with the U.S. States layer:
      Whose POPULATION 2000 is Greater Than or Equal to 1211537 AND Whose MEDIANAGE Less than 35.0
      What question does this query answer?
      What states have a population greater than 1211537 and a median age less than 35?
      Eleven states are selected.
    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 Query Builder In the U.S. States layer:
      NAME Starts with A
      What result do you get and why?
      This query returns four states: AZ, AL, AR and AK. They are all the States that start with the letter A.
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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 Analyze window. In your discussion group, post the question you asked, the statement you used, and the result of your query along with the screenshots. These are the screenshots that are 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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    Resources


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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 My World

    Movie Icon Find Tool My World

    Movie Icon Query Builder My World

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    iPod Versions

    Download these version to play on your iPod or iPhone.

    Movie Icon Adding Layers My World

    Movie Icon Find Tool My World

    Movie Icon Analyze Mode in My World


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