| Answer Key Texas Aquatic Communities | |
| 1. Identify the four longest river systems in Texas. | |
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Answer: The Rio Grande River, the Colorado River, the Red River, and the Brazos River.
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| 2. What is the orientation of most Texas rivers and in what direction do they flow? How did you determine the direction of flow? | |
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Answer: Most rivers in Texas are oriented northwest to southeast. They flow towards the southeast. This can be determined by the facts that elevation gradually declines from west to east and the Gulf of Mexico and Atlantic Ocean are the ultimate repository for surface waters flowing east of the Continental Divide.
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| 3. Study the surface water quality map posted on this page. What is your assessment of the condition of our surface waters? Can you find data presented within the article to support your answer? If so, summarize that data in your response. | |
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Answer: Student answers will vary, however, most will probably indicate that large portions of our surface waters seem to be polluted or “quality impaired.” According to the article, 177 streams and rivers covering over 2200 miles did not meet water quality standards.
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| 4. According to the article (written in 2002), how many fish kills were reported in the previous 5 years? What were the three primary causes of those fish kills? | |
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Answer: 358 fish kills were reported. Primary causes include oxygen depletion, presence of toxics and physical damage such as loss of habitats.
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| 5. The Hill Country region is the source of at least three major rivers – the Guadalupe, the Medina and the Nueces. In addition to serving as a source region in this highland country, what other major water related feature is discussed in the narrative describing this region? In what way(s) is this feature important? | |
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Answer: Underground lakes serve as fresh drinking water for humans and fulfill agricultural needs (farming) in addition to serving wildlife habitats.
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| 6. Identify the river that serves as the southern border for the South Texas Plains region. Describe the unique habitat of that region. What animals might be found within that river valley? Hint: Use the wildlife link on the South Texas Plains page to identify animals found in the river valley. | |
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Answer: The Rio Grande is found along the southern border of this region. This region is a subtropic, bordering on tropical environment with high humidity and many tropical species. Animals identified may include: Ocelot, Texas tortoise, jackrabbit, and the Texas longnose snake. Additional species noted by learners may include: rats, mice, rabbits, lizards, and birds.
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| 7. After studying several of the endangered and threatened species, identify at least three factors that contributed to their current status. | |
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Answer: Answers will vary but may include increased water temperature, diminished flow of fresh spring water, and water pollution are all responsible for stressing threatened and endangered species.
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| 8. What major cities are located closest to the Edwards Aquifer? | |
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Answer: San Antonio and Austin, Texas.
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| 9. Identify the sources that supply water to the wetlands. | |
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Answer: Aquifers, springs, rivers and streams.
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| 10. How do wetlands protect communites from flood impacts? | |
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Answer: Wetlands slow the flow of water.
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| 11. Wetlands are regions where water enters from two sources. Identify two sources of Texas wetlands. | |
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Answer: Water enters from rivers from the mainland and from the ocean (Gulf of Mexico) via tidal action.
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| 12. Estuaries in South Texas tend to be quite salty. What conditions contribute to the high saline content? | |
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Answer: Limited rainfall and excessive evaporation
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| 13. What is the Gulf of Mexico watershed? | |
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Answer: It is a region covering 70% of the United States through which fresh water flows, eventually reaching the Gulf of Mexico.
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| 14. When you reach the Texas Coastal State Parks and National Wildlife Refuges page, click on Mustang Island State Park. What type of natural event are visitors likely to be treated to if they visit in the spring and autumn? | |
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Answer: Large numbers of migratory birds pass through the park.
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| 15. In which environment (salt, fresh, or brackish water) would you most likely find oysters? How does their presence benefit the environment in which they live? | |
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Answer: Oysters are found in brackish water. They are filter feeders. This results in filtering and hence cleaning the water in which they live. They improve light penetration to greater depths.
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| 16. Many species “winter” in the coastal wetlands. Why does this occur? | |
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Answer: Many species winter in the coastal wetlands due to an abundance of food.
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