Interpreting a food web worksheet answers environmental science

EVR 3013L Ecology of South Florida Lab

Worksheet #1 Ecology and Ecosystem Service

Name ________________________________________ Panther ID ________________________

Fill in your answers to the questions and problems on this worksheet. Submit the worksheet to the Worksheet #Canvas assignment dropbox. View the following videos prior to working on the worksheet. It might also be helpful to access other reliable websites for additional information to answer the questions.

· Food chains http://www.odysseyearth.com/videos/the-food-chain/

· Food webs http://www.odysseyearth.com/videos/the-food-web/

· Feedback in ecological systems http://ed.ted.com/lessons/feedback-loops-how-nature-gets-its-rhythms-anje-margriet-neutel

· Creating and interpreting graphs https://www.youtube.com/watch?v=9BkbYeTC6Mo

· Lecture video for this week in Blackboard

1. How is a food web different from a food chain?

2. Examine the food web below.

a. Which organisms are producers?

b. What role do producers play in an ecosystem?

c. Why do many arrows point to the American alligator at the top of the food web?

d. What do you think would happen to the food web if the alligators disappeared from the Everglades?

e. What would be the result if applesnails disappeared from the Everglades?

f. Why is periphyton important in the Everglades?

Image result for everglades food chain

3. What is the difference between positive and negative feedback. Given an example of each.

4. Examine the graph below. The red bars represent the abundance of snowshoe hares (the prey). The blue dots show the abundance of lynx (the predator).

a. How are the populations of hares and lynx related over the time from 1980-2010?

b. Is the abundance of the lynx related to the abundance of the hares?

c. Is this an example of positive feedback or negative feedback? What are your reasons?

Graph showing abundance of hares and lynx from 1980-2010

Year

5. Examine the graph below. The Everglades ecosystems are very sensitive to phosphorus levels. Excess phosphorus results in degradation of the ecosystem. Farms located north of Everglades National Park are required to have management plans to reduce phosphorus levels. The laws require that the farms have at least a 25% reduction in phosphorus levels each year. A 25% reduction in phosphorus is shown by the black line on the graph.

a. What is wrong with this graph based on the video about making graphs that you watched?

Image result for phosphorus levels in Everglades

Required % reduction

b. Did the farms meet the required percentage reduction in phosphorus every year? If not, what years did they not meet the requirement?

6. Examine the two graphs below.

a. Does this graph meet the requirement for a good graph from the video?

b. What conclusions can you reach from your study of the water depth graph?

Image result for phosphorus levels in Everglades

c. What conclusion can you reach from your study of the precipitation graph?

Related image

d. How are precipitation and water depth in the Everglades related?

7. Monitoring of certain species can give researchers information about the health of an ecosystems. Birds are often used because they can be identified more easily. In addition the health of bird populations is a signal about the health of an ecosystem because of their position as top predators. Examine the graph below.

a. According to the video you watched, is this a good example of a graph? Note that the abbreviations for bird species are identified in the text below the graph.

b. What observations can you make about the number of bird nests from 1986-2013 from this graph?

c. Which bird species appears most sensitive to changes in the Everglades ecosystem from year-to-year?

8. What did you learn from this laboratory exercise?