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Key Concept Review (Answers to in-text “Concept Checks”)
Chapter 17
1. In the twentieth century, population growth – mainly in developing countries – was
been coupled with a 4.5-fold increase in economic activity per person. The use of
Earth’s resources has not been proportional to the growth in the number of humans.
2. Physical resources result from the deposition, precipitation, or accumulation of useful
substances in the ocean or seabed. Biological resources are living animals and plants
collected for human use and animal feed.
3. Renewable resources are naturally replaced by the growth of marine organisms or by
natural physical processes. Non-renewable resources such as oil, gas, and solid
mineral deposits are present in the ocean in fixed amounts and cannot be replenished
over time spans as short as human lifetimes.
4. The most valuable physical resources are hydrocarbon deposits, mineral deposits, and
fresh water. In each case, terrestrial resources are easier to obtain and less expensive
to develop (until depletion).
5. There is a growing deficit between oil consumption and the discovery of new
reserves. Huge, easily exploitable oil fields are almost certainly a thing of the past.
Oil accumulates over millions of years – it is being extracted roughly one million
timds more rapidly than it is being generated by slow natural processes.
6. The largest known reservoir of hydrocarbons on Earth is methane hydrate. Even if
engineers could bring the sediment to the surface before the methane disappeared,
extracting the methane from the sediment and liquefying it for efficient use would be
prohibitively dangerous and expensive.
7. Manganese nodules are rich in manganese and cobalt; magnesium is “mined” from
evaporated seawater.
8. More than 1,500 desalination plants are currently operating worldwide, producing a
total of about 13.3 billion liters (3.5 billion gallons) of fresh water per day. Water
produced by desalination is costly, but other options may not exist in arid locations.
9. The fastest growing viable alternative to oil as an energy source is wind power.
10. Seawater is corrosive to most metals used in terrestrial construction. Installation and
inspection of power-generating devices is more complicated in oceanic locations.
Equipment used in the ocean must be robust to withstand the forces of waves and
11. The contribution of marine animals and plants to the human intake of all protein is
small, probably around 4%.
12. Fish, crustaceans, and mollusks are the most valuable living marine resources.
13. Harvests are now declining in spite of increasingly desperate attempts to increase
yields. Since 1970 the world human population has grown; so the average per capita
world fish catch has fallen significantly.
14. Overfishing occurs when so many fish have been harvested that there is not enough
breeding stock left to replenish the species.
15. Bycatch is a term used to describe animals unintentionally killed while collecting
desirable organisms.
16. Norway, Iceland and Japan continue to take whales. Canada and Russia lead in the
harvest of pinnipeds.
17. Shrimp mariculture is the fastest growing and most profitable segment, with an
annual global value exceeding US$17 billion in 2008. Salmon and tilapia are also
extensively grown in mariculture/aquaculture production facilities.
18. Acyclovir, an anti-virus agent, is the most widely used pharmaceutical derived from
the ocean. Many others are in use or under development for a variety of human and
animal disorders.
19. Transportation and recreation are the main nonextractive marine resources.
20. Since the advent of shipping containers, average shipping costs have fallen from 15%
of the retail value of a product to about 0.5%.
21. The Port of Louisiana (centered on New Orleans) is America’s largest. The primary
export is grain from Midwestern farms.
22. The world’s largest industry is tourism. What better places to visit than oceanic
23. One chapter of Grotius’ work De Jure Praedae, which defended free ocean access for
all nations, was reprinted in 1609 under the title Mare Liberum (A free ocean). Mare
Liberum formed the basis for all modern international laws of the sea.
24. Nations hold sovereignty over resources, economic activity, and environmental
protection within their exclusive economic zones.
25. The United Nations holds nominal control over Law of the Sea policies.