Environmental Oceanography: Topics and Analysis
For Students

Issues Questions

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1:  How many kilograms of killer whale would be produced by 10,000 kg of diatoms?

2:  Let us look at this from a different perspective: How many kilograms of diatoms are needed to build 1 metric ton (1,000 kg) of killer whale?

3:  How many kilograms of diatoms are needed to build 1 metric ton (1,000 kg) of blue whale?

4:  This diatoms-krill-blue whale pathway is a very effi cient and unusually short food chain. It is thought that the process of fi lter feeding allows this pathway to exist. How much more effi cient is this diatoms-krill-blue whales food chain than the longer one we examined in Question 14-1?

5:  Explain why fi lter feeding by blue whales enables them to grow so large.

6:  Phytoplankton production (and population size) can be reduced by the increased intensity of ultraviolet radiation. If the starting diatom biomass from Question 14-1 (10,000 kg) is reduced by 12%, how many kg of killer whale would then be produced (use the same 15% ecological effi ciency value)?

7:  If the starting diatom biomass from Question 14-1 (10,000 kg) is reduced by 12%, how many kg of blue whale would then be produced (use the same 15% ecological effi ciency value)?

8:  Is the potential decrease in blue whale and killer whale mass, resulting from decreased diatom production as a result of ozone depletion, cause for concern? Why or why not?

9:  What would be the impact on blue whales should large-scale “mining” of krill take place? On Weddell seals? On orca? On other species? What additional information would you need to answer this question fully?

10:  Currently, most krill taken in fi sheries are used as bait and livestock feed. In addition, krill are fed to farmed fi sh to heighten their red color. Comment on the environmental impact of using krill for animal feed.

11:  Propose solutions to the problems outlined in this issue. What are the impediments to implementing your solutions? Discuss.

12:  Is one of the lessons from this issue that humans should eat krill or even shrimp (see Issues 18 and 19)? Why or why not?

13:  Discuss a potential large-scale krill fi shery from the perspective of sustainability.

14:  Describe the decline in krill in “Krill Central” in the past 30 years.

15:  Explain why British Antarctic Survey scientists conclude that krill have declined.

16:  Describe the decline over the past 30 years in Adelie penguins, which depend on krill as a food source.

17:  Explain whether you can conclude that the decline in krill as a food source is the cause for the decline in the Adelie penguin population.

18:  Discuss why krill are called a “linchpin of marine life” in the Antarctic at the beginning of this report.

19:  Why are the Farallons referred to as the “smoke alarms for climate change”?

20:  How are winds related to the appearance of krill around the Farallon Islands?

21:  How may global climate change be implicated in the disappearance of key bird species like the Cassin’s Auklet?

22:  How might these changes be related to potential declines in commercially important fi sh species from Alaska to Baja California?

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