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

Transcription

1 By Betsy Youngman Guiding Question Learning Objectives What are the limits on the spread of invasive species? Students 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 Project Duration Three or four 45-minute class periods Grade Level Grades (ages 14-18) Subjects Biology Ecology Environmental Science Project 5 of Investigating Your World with My World GIS Copyright 2012 National Geographic Society. Photographs by Jule Muegge, My Shot (top left); Omar Fernandez, My Shot (top right); Andy Davis, My Shot (bottom) 5 Alien Invasion: The Spread of Invasive Species in the United States

2 TEACHER INSTRUCTIONS Alien Invasion: The Spread of Invasive Species in the United States By Betsy Youngman What are the limits on the spread of invasive species? Activity Overview In 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 Information Invasive 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 Strategies Begin 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. Alien Invasion: The Spread of Invasive Species in the United States Teacher Instructions Page 91

3 TEACHER INSTRUCTIONS 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: Additional Resources National Geographic Education s Encyclopedia entry and photographs for invasive species: nationalgeographic.com/education/encyclopedia/ invasive-species/?ar_a=4&ar_r=3 NatGeoEd.org MapMaker 1-Page Maps: mapping/outline-map/?ar_a=1&ar_r=1 National Atlas Invasive Species information: html USDA s National Invasive Species Information Center databases: resources/databases.shtml Data Dictionary Additional information about each of the layers used in this project 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 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 Alien Invasion: The Spread of Invasive Species in the United States Teacher Instructions Page 92

4 STUDENT INSTRUCTIONS Alien Invasion: The Spread of Invasive Species in the United States By Betsy Youngman What are the limits on the spread of invasive species? 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 Mussels 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 INTRODUCTION 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. Headline: Invasive Quagga Mussel Threatens Lake Powell! Arizona Republic May 20, :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. Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 93

5 STUDENT INSTRUCTIONS Find more information about the Zebra Mussel and Quagga Mussel on the U.S. Geological Survey site here: 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 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 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 Hold down the shift key and click the last record with the date 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 , , and 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. Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 94

6 STUDENT INSTRUCTIONS QUESTION 2: How many zebra mussel records are there in each time period? QUESTION 3: In which water bodies (localities) were they found in the 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 Select Spatial Relationship > By Crossing Select Records from U.S. States, which cross records in Zebra Mussels 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 Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 95

7 STUDENT INSTRUCTIONS 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 BEE You 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: 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 Name your new selection Bees This selection will contain records of bee sightings from only 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 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. Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 96

8 STUDENT INSTRUCTIONS 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. Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 97

9 STUDENT INSTRUCTIONS 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 Part III: Escape of the Ornamentals CASE STUDY: TAMARIX, OR SALT CEDAR Believe 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? Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 98

10 STUDENT INSTRUCTIONS 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, This file, named NDVI_ TIFF, shows where the vegetation has greened up with spring vegetation. It is an image file, or GEO TIFF, from June 6, 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? Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 99

11 STUDENT INSTRUCTIONS 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 Locations Further 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. Alien Invasion: The Spread of Invasive Species in the United States Student Instructions Page 100

12 STUDENT ANSWER SHEETS Name Date Alien Invasion: The Spread of Invasive Species in the United States Part I: Migration of the Mussels INTRODUCTION 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? : : : : : Alien Invasion: The Spread of Invasive Species in the United States Student Answer Sheets Page 101

13 STUDENT ANSWER SHEETS Name Date Alien Invasion: The Spread of Invasive Species in the United States 3. In which water bodies (localities) were they found in the time range? 4. Record the number of states that reported zebra mussels in the table below. Dates Number of States Reporting 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? Alien Invasion: The Spread of Invasive Species in the United States Student Answer Sheets Page 102

14 STUDENT ANSWER SHEETS Name Date Alien Invasion: The Spread of Invasive Species in the United States 11. 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. Alien Invasion: The Spread of Invasive Species in the United States Student Answer Sheets Page 103

15 STUDENT ANSWER SHEETS Name Date Alien Invasion: The Spread of Invasive Species in the United States 19. 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 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? Alien Invasion: The Spread of Invasive Species in the United States Student Answer Sheets Page 104

16 ANSWER KEY Name Date Alien Invasion: The Spread of Invasive Species in the United States Answer Key Part I: Migration of the Mussels INTRODUCTION a. When, where, and how were quagga mussels introduced into the United States? The quagga mussel was first recorded in the Great Lakes in September 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. b. How are they alike and different than the zebra mussel? They prefer cooler deeper water. They both are filter feeders and eat large amounts of phytoplankton altering the food web and increasing water clarity. c. What ecological threats do the quagga and the zebra mussels pose to native lake ecosystems? They both eat large amounts of phytoplankton, altering the food web. d. How do these invaders travel? They attach themselves to boats. CASE STUDY: THE ZEBRA MUSSEL IN AMERICA S WATERWAYS 1. List five rivers where mussels have invaded. Arkansas, Hudson, Ohio, Mississippi, Illinois 2. How many zebra mussel records are there in this time period? : 5 records : 1204 records : 951 records : 192 records : 83 records Alien Invasion: The Spread of Invasive Species in the United States Answer Key Page 105

17 ANSWER KEY Name Date Alien Invasion: The Spread of Invasive Species in the United States Answer Key 3. In which water bodies (localities) were they found in the time range? They started in the Great Lakes and moved via the Illinois River to the Mississippi. 4. Record the number of states that reported zebra mussels in the table below. Dates Number of States Reporting What general trend do you see in the data? The number of states seems to be increasing. 6. In which direction are the mussels headed? west and south 7. What limiting factors might control their spread? Water availability and temperature. 8. Do the zebra mussels have any natural predators? None; they are very difficult to eradicate. 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. The Africanized bee arrived in Brazil in the 1950 s. From Brazil, they travelled to the United States and arrived in the 1990s. 10. How has it bred with other bees to become more common? It has bred with the native honeybee and naturalized. Alien Invasion: The Spread of Invasive Species in the United States Answer Key Page 106

18 ANSWER KEY Name Date Alien Invasion: The Spread of Invasive Species in the United States Answer Key 11. So far, what has limited the spread of the bee? 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. 12. Record the date of their first appearance Fill in a table below with the year the bees first appeared, number of sightings, and state names. Dates Number of Sightings State Name Texas Texas Texas TX, NM, AZ AR, FL, OK, NM, TX, LA 14. From the time they first arrived in the United States, how many years did it take for the bees to reach Arizona? Which years have the most sightings? 1992 and What minimum average monthly temperature seems to be too low for Africanized honeybees to spread? The bees don t seem to go above the freeze line, except in parts of Arizona and Nevada. 17. Are there any anomalies? (In other words, do any areas of Africanized honeybee sightings not follow the general trend?) The bees should be in more southeastern states. 18. Use this information to explain why the bees might not be able to invade to Louisiana, Alabama, and Georgia. Too much rain falls in these states. Alien Invasion: The Spread of Invasive Species in the United States Answer Key Page 107

19 ANSWER KEY Name Date Alien Invasion: The Spread of Invasive Species in the United States Answer Key 19. How do you think climate change might affect the spread of the bees? If it becomes warmer and _ drier the bees may move to more states, especially in the western United States and Canada. 20. On a paper map, sketch where you predict Africanized honeybees will have spread by the year Answers will vary. Part III. Escape of the Ornamentals CASE STUDY: TAMARIX, OR SALT CEDAR 21. In which states has tamarix been sighted? Tamarix has been in California, Oregon, Idaho, Montana, Wyoming, Nebraska, Kansas, Oklahoma, Texas, New Mexico, Arizona, Utah, Colorado. 22. What relationship do you see between rivers and tamarix? 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. 23. Name five Arizona streams that have been invaded by tamarix. Answers will vary. 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. The Colorado, Salt, Verde, _ Santa Maria, Bill Williams, and many others. b. Where would you send your land management team next? The tamarix will most likely move North into states like Idaho and Washington next. Alien Invasion: The Spread of Invasive Species in the United States Answer Key Page 108