Climate Change: Polar Bears and Arctic Food Webs Based on what you’ve learned from the readings, the interview and video on the previous page of this module, answer the following questions. 1. Why do polar bears need sea ice? What is their prey? Describe the connection between sea ice and polar bear feeding.
2. Look at NASA’s graph of Arctic sea ice extent in September from approx. 1980-2020. Using data from the graph (give actual numbers- can be a range), compare the sea ice extent during the 1980-1984 time period to the sea ice extent during the 2016-2020 time period. Make sure you use the correct units for sea ice extent in your answer. 3. In what two specific ways is Arctic sea ice changing in a manner that is detrimental to polar bear populations?
4. In the audio interview, Dr. Steven Amstrup, Chief Scientist for Polar Bears International, compares sea ice platforms to what in terms of polar bear feeding (what does he compare sea ice to)?
5. What are some results of longer and longer sea ice absence in terms of polar bears from areas like Baffin Bay?
6. What are polar bears starting to feed on instead of
their typical diet? In what ways is this dietary substitute not nutritionally adequate for the polar bears?
7. Read about trophic cascades in our module and describe, in your own words, what the term “trophic cascade” means. To get credit, your answer must be in your own words and not copied from the definition in the assignment reading. 8. If polar bear populations continue to decline as predicted due to melting sea ice, propose a potential trophic cascade that may result. Accompany your description of this change with a food chain diagram and follow potential changes in the food chain all the way to the primary producer level. You can use the food web diagram in the “Climate Change: Arctic Food Web” page of this module to help you. For full credit on this question, you need to include the food chain and also the change to the food chain that would occur due to melting sea ice.
