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Project 5 of Investigating Your World with My World GIS • www.natgeoed.org/MyWorldGIS

Alien Invasion: The Spread of Invasive Species in the United States By Betsy Youngman

Guiding QuestionWhat are the limits on the spread of invasive species?

Project Duration Three or four 45-minute class periods

Grade Level Grades 9–12+ (ages 14-18)

Learning ObjectivesStudents will be able to: • read and analyze maps of invasive

species and climate • describe limits on the spread of

invasive species • download and import shapefiles and

add fields to shapefiles

Subjects• Biology• Ecology• Environmental Science

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Alien Invasion: The Spread of Invasive Species in the United States • Teacher Instructions • Page 91

By Betsy Youngman

Alien Invasion: The Spread of Invasive Species in the United States

What are the limits on the spread of invasive species?

Activity OverviewIn this lesson, students investigate factors that limit the spread of invasive species in the United States. They compare the spread and limiting factors of three classes of invasive species—insects, plants, and aquatic invertebrates—through data sets from the National Atlas and readings on invasive species issues. Through this activity, students also download a shapefile from the Internet and successfully import it into My World GIS, and they add a field to a shapefile. GIS users with this combination of skills can begin to access data from a rapidly increasing pool of freely available data, which will enable the independent use of data.

Background InformationInvasive species issues are a key environmental science concept, and the impact on global biodiversity is a major concern to many scientists. An invasive species is an organism that is not indigenous, or native, to a particular area. Invasive species can cause great economic and environmental harm to the new area. Not all non-native species are invasive. For example, most of the food crops grown in the United States, including popular varieties of wheat, tomatoes, and rice, are not native to the region. To be considered invasive, a species must harm property, the economy, or the native plants and animals of the region and also must adapt to the new area easily and reproduce quickly. Many invasive species are introduced into a new region accidentally. Zebra mussels are native to the Black Sea and the Caspian Sea in Central Asia. They arrived in the Great Lakes of North America accidentally, stuck to

large ships that traveled between the two regions. There are now so many zebra mussels in the Great Lakes that they have threatened native species.

Connections to National Standards NATIONAL SCIENCE EDUCATION STANDARDS, GRADES 9-12• Standard A-1: Abilities necessary to do scientific

inquiry• Standard C-4: Interdependence of organisms• Standard F-4: Environmental quality• Standard F-5: Natural and human-induced hazards• Standard F-6: Science and technology in local,

national, and global challenges

NATIONAL GEOGRAPHY STANDARDS• Standard 1: How to Use Maps and Other Geographic

Representations, Tools, and Technologies to Acquire, Process, and Report Information From a Spatial Perspective

• Standard 14: How Human Actions Modify the Physical Environment

• Standard 18: How to Apply Geography to Interpret the Present and Plan for the Future

Teaching StrategiesBegin with a discussion of the key questions, a well as background information on invasive species from www.NatGeoEd.org. Since most students will not be familiar with some species of plants and animals in the activity, it may be helpful to share photographs before beginning each part of the lesson. See the Resources section for websites with additional information.

To do the investigation using My World GIS, have students work in pairs at computers. Give each pair the Student Instructions, the Answer Sheet, and a blank outline map of the United States.

TEACHER INSTRUCTIONS

TEACHER INSTRUCTIONS

Alien Invasion: The Spread of Invasive Species in the United States • Teacher Instructions • Page 92

Vocabulary• temperature, noun—degree of hotness or coldness

measured by a thermometer with a numerical scale.• precipitation, noun—all forms in which water falls to

Earth from the atmosphere.• weather, noun—state of the atmosphere, including

temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

• climate, noun—all weather conditions for a given location over a period of time.

• invasive species, noun—a type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.

Extending the Learning• Have students report on and map another invasive

species of interest.• Students can view the video “Cane Toads: An Unnatural

History,” a fascinating and informational documentary illustrating Australia’s cane toad invasion.

• Working in small groups, have students survey invasive species in their own schoolyard, parks, or neighborhoods. They can collect data to support a research question of their own design, and they can use the online National Atlas mapmaker: http://www.nationalatlas.gov/

Additional Resources• National Geographic Education’s Encyclopedia entry

and photographs for invasive species: http://education.nationalgeographic.com/education/encyclopedia/invasive-species/?ar_a=4&ar_r=3

• NatGeoEd.org MapMaker 1-Page Maps: http://education.nationalgeographic.com/education/mapping/outline-map/?ar_a=1&ar_r=1

• National Atlas Invasive Species information: http://www.nationalatlas.gov/articles/biology/a_invasive.html

• USDA’s National Invasive Species Information Center databases: http://www.invasivespeciesinfo.gov/resources/databases.shtml

• Africanized Bee: A layer with Africanized Bee data from the National Atlas

• AZ Streams With Tamarix: Subset of streams data from Arizona Geographic database

• NDVI geotiff June 01 09: Shows vegetation index for June 2009. Downloaded from NASA NEO

• Tamarix: A layer showing extent of Tamarix invasion from USGS National Invasive Species Database

• Precipitation: Average annual precipitation for the conterminous United States from 1961 through 1990, from PRISM

• Zebra Mussels: A layer with Zebra Mussels data from the National Atlas

Data DictionaryAdditional information about each of the layers used in this project

In this investigation, you will learn why invasive species cause problems, and you will use My World GIS to map and compare the spread and limiting factors of

three classes of invasive species: insects, plants, and aquatic invertebrates. In completing this activity, you will be able to open a My World project and activate a layer, edit a layer’s appearance, query a dataset, sort data by attributes, download a shapefile from the Internet, import a shapefile

into My World, join an existing shapefile to a new field, and edit a layer’s information.

Use the student answer sheet to record your answers for this investigation.

Part I: Migration of the MusselsINTRODUCTION While eating breakfast one morning, you glimpse a local Arizona newspaper and read the headline and story below. You begin to wonder, “What on Earth is a quagga mussel? And how can a little mussel be ‘invasive’?” You decide to investigate further.

Alien Invasion: The Spread of Invasive Species in the United States • Student Instructions • Page 93

STUDENT INSTRUCTIONS

By Betsy Youngman


What are the limits on the spread of invasive species?

Arizona Republic May 20, 2007 02:17 PM

FLAGSTAFF—Wildlife officials fear an invasive mussel that has been spotted in lakes throughout Arizona will next be introduced to Lake Powell north of Page. The quagga mussel has appeared in lakes Mead, Havasu and Mohave. Now, managers at Lake Powell are doing whatever they can to keep the organisms out. If the mussels show up in the lake, they could cause boat motors to overheat and docks and the shoreline to be littered with sharp, smelly shells.

“Basically, the way I see it, just about anything that someone might value about Lake Powell is threatened by this,” said Mark Anderson, aquatic ecologist for Glen Canyon National Recreation Area. The strength of quagga mussels lies in their numbers. Dubbed “ecological engineers,” the species can populate to a density of hundreds of thousands per square yard and deprive fish and other organisms of food.

There is no effective means of killing the organisms across a large lake, short of poisoning everything. “They’re devastating. I haven’t seen anything good about them,” said Wayne Gustaveson, fisheries biologist for the Utah Division of Wildlife Resources.

If the mussel gets to Lake Powell, officials say it will most likely be via one of the 100,000 boats that visit the lake every year. If even one of those boats has been exposed to the mussel and not been washed in hot or high-pressure water afterwards, then the mussel has a good chance of establishing in the lake.

Boaters are supposed to fill out a piece of paper saying they’re not likely to expose the lake to mussels. But there’s no penalty for not filling out the paper. Anderson said it’s an honor system. “We’re hoping that we can educate people about this so they won’t try to subvert it,” he said. “If they try, they can do so easily.” Downstream, Lake Mead is attempting to wash houseboats and boats moored for a long time in the lake to prevent the spread elsewhere, a spokeswoman said. That lake sees up to 5,000 boats in a weekend.

Quagga mussels were introduced accidentally to the Great Lakes region in the ballast of ships from Eastern Europe and the Ukraine. They can plug pipes up to 12 inches in diameter, and restrict flow in larger pipes.

Headline: Invasive Quagga Mussel Threatens Lake Powell!



Find more information about the Zebra Mussel and Quagga Mussel on the U.S. Geological Survey site here: http://nas.er.usgs.gov/taxgroup/mollusks/zebramussel/ On your answer sheet, answer the following questions:a. When, where, and how were quagga mussels introduced into the United States?b. How are they similar to and differ from the zebra mussel? c. What ecological threats do the quagga and the zebra mussels pose to native lake ecosystems? d. How do these invaders travel?

CASE STUDY: THE ZEBRA MUSSEL IN AMERICA’S WATERWAYS 1. Launch My World. Open the Invasive Species.m3vz project by dragging it to the Layer List or by double-clicking on the

project name under the All Projects menu. You will see a map that is zoomed in to the United States. If your map is not centered on the United States, use the Move Map and Zoom tools to do so.

2. Observe the spread of the zebra mussels through U.S. rivers:• Turn on the Zebra Mussels layer to see where the mussels are today.• Turn on the U.S. Rivers layer. Make it the active layer by clicking anywhere in the blank area next to the name. • Select the Get Information button in the map toolbar. • Click the U.S. Rivers layer with the Get Information tool. • Click the rivers in the U.S. Rivers layer to determine which major U.S. rivers have been invaded by zebra mussels

through 2008.

QUESTION 1: List five rivers where mussels have invaded.

3. Investigate the movement of mussels across the waterways.

Turn on the U.S. Lakes layer. Click the Open Analysis Window button. In the Analyze mode, one can conduct many types of analysis of the data presented in a GIS project.

• In Analyze, Choose Select > By Value. • Select records from Zebra Mussels whose Year is before 1989 and is on or after 1987. • Hint: To enter the date values, click the year and type in the new value.• Do NOT check the make selection a new layer box. • Name your selection Zebra Mussels 87-89, and click OK. • Alternatively—Click the table button to open the table for zebra mussels. Click the first record from 1988. Hold

down the shift key and click the last record with the date 1989. You have now made a selection from the records. • Return to the Map Window. Click the Show Table of Active Layer button for information on your new selection.

Repeat this selection procedure three more times to find the zebra mussels’ spread from 1990–1995, 1996–2000, 2001–2005 and 2006–2008. You will now have four selection sets on your map.

Turn these selections on in sequential order to see the march of the zebra mussels across the United States. You will use these selections in the next section of the activity.



QUESTION 2: How many zebra mussel records are there in each time period? • 1987–1989• 1990–1995• 1996–2000• 2001–2005• 2006–2008

QUESTION 3: In which water bodies (localities) were they found in the 1987-1989 time range?

Next, determine whether zebra mussels are a national issue or not. Return to Analyze mode, and then choose the U.S. States that cross the zebra mussel records for each time period, 87-89, 90-95, 96- 00, 01- 05, and 06-08. • Select Spatial Relationship > By Crossing • Select Records from U.S. States, which cross records in Zebra Mussels 87-89. Do not make it a new layer.

• Return to the Visualize window, and turn on the U.S. States layer to see your highlighted selections. Hint: Turn off the zebra mussels layer to see only the selected states.

QUESTION 4: Record the number of states that reported zebra mussels. Dates Number of States Reporting

1988–1989

1990–1995

1996–2000

2001–2005

2006–2008



QUESTION 5: What general trend do you see in the data?

QUESTION 6: In which direction(s) are the mussels headed? (north, south, etc)

QUESTION 7: What limiting factors might control their spread?

QUESTION 8: Do the zebra mussels have any natural predators?

Turn off the Zebra mussel and the U.S. Rivers layers. On the U.S. States layer, choose Show All (highlighting off) to hide your selections.

Part II: Insect Pests: Do They Travel as Easily as the Water Borne Ones? CASE STUDY: THE AFRICANIZED BEEYou have already read about the zebra mussel invasion, when you hear on the local news, “Young man falls from a cliff while climbing a local mountain. The man, observers report, was trying to escape an attack of the Africanized killer bees.” You of course think, What next!? And where can I move to escape these pests? Find out more about these true pests.

1. In My World, turn on the Africanized Bees layer. With the Link tool active, click the base of the project link flag pole Use links from the project to the Internet to learn more about this bee. You can also find additional bee information here: http://www.nationalatlas.gov/articles/biology/a_bees.html Answer the following questions:

QUESTION 9: Did the bee actually come to the United States from Africa?

QUESTION 10: How has it bred with other bees to become more common?

QUESTION 11: So far, what has limited the spread of the bee?

2. To track the spread of the bees, return to the My World map. Observe the map legend at the bottom of the page—or you can use the table of the Africanized Bees layer—to determine when the first Africanized honeybee sightings were reported in the United States:

QUESTION 12: Record the date of their first appearance.

Click the Open Analysis Window… button to return to Analyze mode. In Analyze, create a selection to show the first counties reporting Africanized bee sightings. • Click Select > By Value. • Select records from Africanized Bees whose year is before 1991, and is on or after 1990. Name your new selection Bees

1990. This selection will contain records of bee sightings from only 1990. • Click the Visualize tab to return to the map. You should now see your selection highlighted in magenta. If not, use the

highlight mode pull down menu to change your preference for the selection. Repeat the selection process described above to select the records for each individual year, through the year 2005.

• Activate your selections by clicking the radio buttons next to their names. With the radio button highlighted blue, click the Show Table of the Selected Layer button above the layer list to view the records from the selection.



• Note: You can Sort a field by clicking on the field name. Each click will sort the field—ascending, descending, and then back to unsorted.

QUESTION 13: Fill in the table with the year the bees first appeared, number of sightings, and state names.

QUESTION 14: From the time they first arrived in the U.S., how many years did it take for the bees to reach Arizona?

Examine the number of recorded bee sightings per year. • With the Africanized Bees layer still active, click the Histogram/Bar Chart button . • From the View Histogram/Bar Chart for Field: dropdown menu at the top of the new window, choose Year. • Use the slider to change the number of bins to 8 to 16. You will see a bar graph.

QUESTION 15: Which years have the most sightings?

Close the Histogram window. Compare the spread of Africanized honeybees to Average Surface Temperature and Precipitation to look for possible natural limiting factors in their spread. Prepare your map for the investigation. • Edit the appearance of the Continents layer. • Click the fill color tab and change the transparency of the Continents layer to 100%. • Click Apply. This change will allow you to see only the continent outlines.

Now, edit the appearance of the Africanized Bees layer. • Change the transparency of the Africanized Bees layer to 35% and change the color scheme to gray. • Change the transparency of the last data file “1970” to 100%. • Click its color field and slide the slider towards the 100%. This will eliminate any areas with no data.

3. Compare temperature and bee spread. Turn on and activate the 30-yr Average Surface Temperature layer. Select the temperature layer, and use the dropdown

menu in the layer to select Minimum of Average Monthly Temps as your active legend. • In Analyze mode, select records from the 30 year Average temperatures whose Minimum of Average Monthly Temps is

less than 1˚ Celsius. • Make this a new layer; name it Freeze Line.• Turn the Africanized Bees layer on and off in order to uncover trends in the spread of Africanized honeybees compared

to minimum average monthly temperature.

QUESTION 16: What minimum average monthly temperature seems to be too low for Africanized honeybees to spread?

QUESTION 17: Are there any anomalies? (In other words, do any areas of Africanized honeybee sightings not seem to follow the general trend?)

4. Compare precipitation and bee spread.• Turn on the 30-year Average Precipitation PRISM layer. • Use the Analyze mode to find the areas of the United States that receive less than 55 inches of rainfall each year.

Observe the similarities between bee patterns and precipitation.

QUESTION 18: Use this comparison to explain why the bees might not be able to invade Louisiana, Alabama, and Georgia.



QUESTION 19: How do you think climate change might affect the spread of the bees?

QUESTION 20: On a printed map of the United States, highlight in colored pencil where you think the Africanized bees will have spread by the year 2015.

Part III: Escape of the Ornamentals CASE STUDY: TAMARIX, OR SALT CEDARBelieve it or not, most invasive species don’t fly, swim, or crawl; they’re actually plants. In this section, you will investigate a major plant invader in the American West.

Prized for its pink blossoms and needle-like leaves, tamarix, or salt cedar, is a small ornamental shrub or tree that was imported to U.S. from Central Asia and the Mediterranean in the mid-1800’s. It was valued not only for its beauty, but also for its ability to stabilize stream banks and to provide shade in the hot climate of the Southwest.

Unbeknownst to its admirers, though, tamarix was an aggressive, invasive pest. It quickly escaped cultivation and grabbed a hold of fertile riparian zones in the desert southwest. Its rampant invasion continues today, more than 100 years later. In the U.S., it is estimated that the damage from tamarix and its removal costs taxpayers millions of dollars. The seeds of tamarix are spread by wind and wildlife. These seeds, viable for up to six weeks, can take root in areas that have been disturbed by grazing, flooding, or fire. Tamarix is highly successful because it can tap into the water table as much as 100 feet below the surface. It’s been known to use up to 200 gallons of water per plant, per day!

Once established, tamarix is extremely difficult to control or eradicate. In order to remove it, teams of volunteers use special jacks to dig up and dispose of the plant’s roots, one tree at a time—a hot, sweaty and seemingly endless task. Since efforts to eradicate existing tamarix stands seem nearly impossible, land managers and scientists have changed their tactics to prevent of establishment of new stands.

1. Add tamarix data to the map, and edit the data properties. If necessary, re-launch My World and open the project file, Invasive Species.m3vz. • Turn on the Tamarix Sightings layer.• Turn on the U.S. Rivers layer• Turn off the Precipitation layer

Edit the properties of the Tamarix Sightings layer. To change the properties of a layer, in this case tamarix, • Double click the layer’s name in the Layer List.• Then select the tabs change the shape, size, or color of the symbol in the Edit Appearance window. Choose Magenta

for the color of tamarix sightings. • Click Apply to apply the changes. • Click OK to close the Edit Appearance window.

QUESTION 21: In which states has tamarix been sighted?

QUESTION 22: What relationship do you see between rivers and tamarix?



2. Zoom into the southwest, add elevation data, and analyze the limitations to the spread of tamarix. • Use the Zoom tool to zoom in to the state of Arizona, where the tamarix invasion is the most severe.• Turn on the AZ Streams with Tamarix layer. Immediately, you will see that many Arizona streams have been invaded.• With the AZ Streams with Tamarix layer active, open its Attribute table.• Sort the streams by Name for a list of the names of the streams.

QUESTION 23: Name five Arizona streams that have been invaded by tamarix.

3. There are additional limitations to the spread of tamarix. It needs wet conditions to survive its first year, but some tamarix invasions do not appear to be in streams. In this section, you will discover what types of areas might also be suitable habitat for tamarix.

Tamarix is known to prefer elevations below 2000 meters. Find these levels on your map. • Turn on the Elevation 48 States layer. Zoom to the full extent of this layer. • Optional: Edit the Appearance of this layer. • Choose Fill Color by Gridcode, Colorscheme elevation; set the Fill Color count to 9 classes. • Set the Outline Color to Uniform and the Transparency to 100%.• Click Apply and Close.

The map will now be color-coded by elevation. Refer to the attribute table of the elevation layer to relate gridcode to elevation. Record the gridcode of layers areas that are above 2000 m. • In the Analyze Window, select all the records for files whose grid code is greater than or equal to 8. Click OK. • My World will now find all the records that match your query. These areas will be highlighted in yellow on the map. • Use the Zoom and Pan tools to look at the map. Are there many tamarix sightings at elevations above 2000 meters?

What climate conditions change at this elevation? • Turn off the Elevation 48 States layer.

4. Next you will add satellite data to connect tamarix spread with a vegetation index (NDVI.) Scientists at NASA and USGS have used habitat preferences, such as moist soils and low elevations, to begin to predict tamarix appearance, and they also are able to use satellite data to view where vegetation is most likely to be successful.

• Turn on the vegetation index image file from June 1–July 1, 2009. This file, named NDVI_6.1.09.TIFF, shows where the vegetation has “greened up” with spring vegetation. It is an image file, or GEO TIFF, from June 6, 2009. Double click it in the Layer list.

• If necessary, adjust the layers so that the image is under that U.S. States and Tamarix Layers or at the bottom of the layer list. If necessary, turn off the Continents layer.

• Choose Zoom to the extent of the active layer, in this case, Tamarix sightings.• Compare the location of the points to the green regions of the image. Areas with healthy vegetation, and below 2000

m, are prime locations for new invasions of tamarix. • Once again turn on the U.S. Rivers and Elevation 48 layer. Based on this NDVI image, the elevation layer and the U.S.

Rivers data, predict the direction you think tamarix will move in the next few years in the U.S. Southwest.

QUESTION 24: Use the Get Information tool and the layers in the project to answer the following: a. Which rivers seem to be the most likely to be invaded?b. Where would you send your land management team next?



Save your work. Choose the File > Save As command from the file menu. Name your project with your own name.

Part IV: Explore Invaders in Other LocationsFurther investigate an invasive species of your choice. Research the ecological, economic, and public health risks that invasive species can pose. Choose an invasive species local to an area of interest to you. Research this species and design a short presentation on the species of your choice. Include a map in your presentation.

Include the following topics in your presentation.• What is the species? Is it a plant, animal, or insect? • How was the species introduced to this country? • Where did it come from? • Why was it introduced? Was it accidental or intentional? • What are the issues/problems created by this species?• What are the methods of eradication for this species? • Find a printable map or shapefile that documents the spread of this pest. Download this data and add it to your

presentation’s map.

Name __________________________________________ Date ______________________________


Alien Invasion: The Spread of Invasive Species in the United States • Student Answer Sheets • Page 101

STUDENT ANSWER SHEETS

Part I: Migration of the MusselsINTRODUCTION

a. When, where, and how were quagga mussels introduced into the United States?

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

b. How are they similar to and different from the zebra mussel? ______________________________

____________________________________________________________________________________

____________________________________________________________________________________

c. What ecological threats do the quagga and the zebra mussels pose to native lake ecosystems?

____________________________________________________________________________________

d. How do these invaders travel? _________________________________________________________

CASE STUDY: THE ZEBRA MUSSEL IN AMERICA’S WATERWAYS

1. List five rivers where mussels have invaded.

______________________________________________________________________________________

2. How many zebra mussel records are there in this time period?

1987–1989: ___________________________________________________________________________

1990–1995: _________________________________________________________________________

1996–2000: ___________________________________________________________________________

2001–2005: __________________________________________________________________________

2006–2008: __________________________________________________________________________



Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States3. In which water bodies (localities) were they found in the 1987–1989 time range?

______________________________________________________________________________________

4. Record the number of states that reported zebra mussels in the table below.

Dates Number of States Reporting

1988–1989

1991–1995

1996–2000

2001–2005

2006–2008

5. What general trend do you see in the data? ________________________________________________

6. In which direction are the mussels headed? ________________________________________________

7. What limiting factors might control their spread? ___________________________________________

8. Do the zebra mussels have any natural predators? ___________________________________________

Part II: Insect Pests: Do They Travel as Easily as the Water Borne Ones? CASE STUDY: THE AFRICANIZED BEE

9. Did the Africanized bee actually come to the U.S. from Africa? Explain. _______________________

______________________________________________________________________________________

10. How has it bred with other bees to become more common? _________________________________

______________________________________________________________________________________



Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States11. So far, what has limited the spread of the bee? ____________________________________________

______________________________________________________________________________________

12. Record the date of their first appearance. _________________________________________________

13. Fill in a table below with the year the bees first appeared, number of sightings, and state names.

Dates Number of Sightings State Name

14. From the time they first arrived in the United States, how many years did it take for the bees to

reach Arizona? _______________________________________________________________________

15. Which years have the most sightings? ____________________________________________________

16. What minimum average monthly temperature seems to be too low for Africanized honeybees to

spread? _____________________________________________________________________________

17. Are there any anomalies? (In other words, do any areas of Africanized honeybee sightings not

follow the general trend?) _____________________________________________________________

18. Use this information to explain why the bees might not be able to invade to Louisiana, Alabama,

and Georgia. _________________________________________________________________________



Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States19. How do you think climate change might affect the spread of the bees? _______________________

_____________________________________________________________________________________

20. On a paper map, sketch where you predict Africanized honeybees will have spread by the year

2015. ______________________________________________________________________________

Part III: Escape of the Ornamentals CASE STUDY: TAMARIX, OR SALT CEDAR

21. In which states has tamarix been sighted? ________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

22. What relationship do you see between rivers and tamarix? _________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

23. Name five Arizona streams that have been invaded by tamarix.

____________________________________________________________________________________

24. Use the Get Information tool and the layers in the project to answer the following:

a. Which rivers seem to be the most likely to be invaded? Explain. __________________________

_____________________________________________________________________________________

b. Where would you send your land management team next? _______________________________

____________________________________________________________________________________

Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States Answer Key

Alien Invasion: The Spread of Invasive Species in the United States • Answer Key • Page 105

ANSWER KEY

Part I: Migration of the MusselsINTRODUCTION

a. When, where, and how were quagga mussels introduced into the United States?

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

b. How are they alike and different than the zebra mussel? __________________________________

____________________________________________________________________________________

____________________________________________________________________________________

c. What ecological threats do the quagga and the zebra mussels pose to native lake ecosystems?

____________________________________________________________________________________

d. How do these invaders travel? _________________________________________________________

CASE STUDY: THE ZEBRA MUSSEL IN AMERICA’S WATERWAYS

1. List five rivers where mussels have invaded.

______________________________________________________________________________________

2. How many zebra mussel records are there in this time period?

1987–1989: __________________________________________________________________________

1990–1995: __________________________________________________________________________

1996–2000: __________________________________________________________________________

2001–2005: __________________________________________________________________________

2006–2008: __________________________________________________________________________

The quagga mussel was first recorded in the Great Lakes in September 1989. The introduction

of D. r. bugensis into the Great Lakes appears to be the result of ballast water discharge from

transoceanic ships that were carrying veligers, juveniles, or adult mussels.

They both eat large amounts of phytoplankton, altering the food web.

5 records

Arkansas, Hudson, Ohio, Mississippi, Illinois

1204 records

951 records

192 records

83 records

They attach themselves to boats.

They prefer cooler deeper water.

They both are filter feeders and eat large amounts of phytoplankton altering the food web and

increasing water clarity.


ANSWER KEY

Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States Answer Key3. In which water bodies (localities) were they found in the 1987–1989 time range?

______________________________________________________________________________________

4. Record the number of states that reported zebra mussels in the table below.

Dates Number of States Reporting

1988–1989

1991–1995

1996–2000

2001–2005

2006–2008

5. What general trend do you see in the data? ________________________________________________

6. In which direction are the mussels headed? ________________________________________________

7. What limiting factors might control their spread? ___________________________________________

8. Do the zebra mussels have any natural predators? ___________________________________________

Part II: Insect Pests: Do They Travel as Easily as the Water Borne Ones? CASE STUDY: THE AFRICANIZED BEE

9. Did the Africanized bee actually come to the U.S. from Africa? Explain. _______________________

______________________________________________________________________________________

10. How has it bred with other bees to become more common? _________________________________

______________________________________________________________________________________

They started in the Great Lakes and moved via the Illinois River to the Mississippi.

The Africanized bee arrived

in Brazil in the 1950’s. From Brazil, they travelled to the United States and arrived in the 1990s.

It has bred with the native honeybee

and naturalized.

The number of states seems to be increasing.

None; they are very difficult to eradicate.

west and south

Water availability and temperature.

1

19

18

17

12


ANSWER KEY

Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States Answer Key11. So far, what has limited the spread of the bee? ____________________________________________

______________________________________________________________________________________

12. Record the date of their first appearance. _________________________________________________

13. Fill in a table below with the year the bees first appeared, number of sightings, and state names.

Dates Number of Sightings State Name

14. From the time they first arrived in the United States, how many years did it take for the bees to

reach Arizona? _______________________________________________________________________

15. Which years have the most sightings? ____________________________________________________

16. What minimum average monthly temperature seems to be too low for Africanized honeybees to

spread? _____________________________________________________________________________

17. Are there any anomalies? (In other words, do any areas of Africanized honeybee sightings not

follow the general trend?) _____________________________________________________________

18. Use this information to explain why the bees might not be able to invade to Louisiana, Alabama,

and Georgia. _________________________________________________________________________

The Africanized bees don’t seem to like wet

conditions, so they do not survive in areas with high rainfall, greater than 55 inches per year.

1990

3

1992 and 2005

The bees should be in more southeastern states.

Too much rain falls in these states.

The bees don’t seem to go above the freeze line, except in parts of Arizona and Nevada.

1990 39 Texas

1991 26 Texas

1992 45 Texas

1993 26 TX, NM, AZ

2005 139 AR, FL, OK, NM, TX, LA


ANSWER KEY

Name __________________________________________ Date ______________________________

Alien Invasion: The Spread of Invasive Species in the United States Answer Key19. How do you think climate change might affect the spread of the bees? _______________________

_____________________________________________________________________________________

20. On a paper map, sketch where you predict Africanized honeybees will have spread by the year

2015. ______________________________________________________________________________

Part III. Escape of the Ornamentals CASE STUDY: TAMARIX, OR SALT CEDAR

21. In which states has tamarix been sighted? ________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

22. What relationship do you see between rivers and tamarix? _________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

23. Name five Arizona streams that have been invaded by tamarix.

____________________________________________________________________________________

24. Use the Get Information tool and the layers in the project to answer the following;

a. Which rivers seem to be the most likely to be invaded? Explain. __________________________

_____________________________________________________________________________________

b. Where would you send your land management team next? _______________________________

____________________________________________________________________________________

If it becomes warmer and

drier the bees may move to more states, especially in the western United States and Canada.

Tamarix has been sighted in California, Oregon, Idaho,

Montana, Wyoming, Nebraska, Kansas, Oklahoma, Texas, New Mexico, Arizona, Utah, Colorado.

In general, tamarix follows rivers.

Note: The U.S. rivers layer in My World does not contain all rivers in the United States. So

although you see tamarix in parts of Nevada and California, the map is not displaying the

invaded river.

Answers will vary.

Answers will vary.

The Colorado, Salt, Verde,

Santa Maria, Bill Williams, and many others.

The tamarix will most likely move

North into states like Idaho and Washington next.

Documents

5 Alien Invasion: The Spread of Invasive Species in the ...media.nationalgeographic.org/assets/file/MW5_Alien_Invasion.pdf · Sea and the Caspian Sea in Central Asia. They arrived