Environmental Oceanography: Topics and Analysis
For Students

Issues Questions

Please read each question below and type your response into each corresponding box. When you are finished, fill out your name, e-mail address, and instructor's e-mail at the bottom of this form, and click submit to send a copy to your instructor.

1:  By what factor is toxaphene concentrated in zooplankton as compared with seawater?

2:  By what factor is toxaphene concentrated in seal blubber compared with its food, arctic char?

3:  Ringed seals are preyed upon by beluga whales. But what factor is toxaphene concentrated in beluga blubber compared with seal blubber?

4:  How many phenyl rings are linked in PCB (hint: what does the prefi x “bi” mean)?

5:  If PCBs are only slightly soluble in seawater, how can adding a small percentage of remaining PCBs to the ocean threaten the extinction of all marine mammals?

6:  Estimate how long it may take for PCB concentrations to fall by one half, assuming that no new PCBs are added to the system.

7:  Marine mammals are particularly susceptible to the harmful reproductive effects of PCBs. Why is biomagnifi cation potentially so dangerous?

8:  Recall the concept of a food chain from Chapter 7, as a concept that ties primary producers to herbivores, fi rst-level carnivores, and so on. Which type food chain, a “short” one with few levels or a long one with many levels, would be more susceptible to the buildup of dangerous levels of POPs? Formulate a hypothesis to test your conclusion.

9:  Some readers may conclude that Greenpeace scientists, one of our sources for this issue, may be too “biased” to provide factual data on PCBs. Research PCBs on the Internet or in an environmental science textbook. Describe any differences in the treatment of the PCB threat you observe.

10:  Which members of the Dirty Dozen were by-products?

11:  In what journal was the map published? If this map was published by Greenpeace, would readers give it equal regard? Why or why not?

12:  What do “red zones” represent?

13:  Where are the reddest of the red zones located?

14:  Characterize the general health of the polar oceans.

15:  Given the projection that climate change is due to affect the poles much more severely than other latitudes, speculate on the “business-as-usual” future of polar oceans.

16:  The Persian Gulf is one of the most degraded zones in the oceans. Give reasons for why this is so.

17:  Where are the most disturbed zones of coastal North America? Explain why this is the case.

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