no topic

ASSIGNMENT 7 The Endless Voyage Lessons 24 – 26
20 points


Treasure Trove

This lesson surveys the major physical, biological, energy, and non extractive resources of the oceans and details their economic worth, means of extraction, distribution, abundance, present status, and future prospects.

Oil and natural gas are the ocean ís most valuable mineral resources. Extraction is often controversial because it can damage beaches, increase the water ís turbidity, increase shoreline erosion, and damage habitat. Other physical resources include several sea salts, which are collected profitably by evaporation or other extractive processes. Seawater is also rich in magnesium and various magnesium compounds.

Potable water is becoming a scarce commodity and this situation is likely to worsen. Desalination of seawater by evaporation, freezing, and reverse osmosis will become an ever-increasing necessity to supply our fresh water as existing sources of ground water, streams, rivers, and lakes are depleted or polluted.

Energy of the motion of waves, currents, and tides can be harnessed to generate electricity but is not presently competitive with traditional generation modes. The ocean’s biological resources are renewable, but demand has resulted in widespread over fishing. Mariculture is a rapidly growing enterprise. Historically, fisheries are a common property resource so management and conservation are difficult. Other marine bio-resources include fur-bearing mammals, seaweeds, algae, and other marine organisms.

Damage to marine ecosystems is probably at or close to crisis levels in most parts of the world ocean. A rational, enforceable, international law of the sea is necessary.

 Treasure Trove

24-1. Where would you look for manganese nodules? What would be some of the problems collecting and extracting their mineral wealth?

24-2. Which current technology seems more feasible, desalination or wave energy?   

24 -3.  If you love to eat seafood, but want to be sure when you do purchase it you avoid supporting mariculture methods that harm the environment, how would you figure that out?

 24-4.   Read the experts from the below case study (taken from feel free to expand your research here) and then read on the internet about the dolphin safe label on tuna.  When you feel informed, explain why buying albacore tuna, even though more expensive, helps you to be sure that the dolphin safe label is more likely to be accurate. (hint: to answer this questions you will want to consider the difference in behavior and methods of fishing used between yellowfin tuna and albacore tuna).

Eastern Tropical Pacific Tuna Purse-Seine Fishery

Every year between 1959 and 1972, the tuna fisherman of the eastern tropical Pacific killed hundreds of thousands of dolphins, mostly spinners and spotted dolphins. In a report by the National Marine Fisheries Service’s Southwest Fisheries Center made in 1979, the estimated total number of dolphins killed between 1959 and 1972 was 3,796,658. That figure is probably an underestimate, since it does not include individuals that were injured in the nets and died later. The level of incidental take is sufficient to pose a serious threat to the survival of some stocks.

The Root of the Problem

The basis of the problem is that the two main species involved associate in large numbers with yellowfin tuna. The nature of the association between the dolphins and the tuna is still a mystery, although there are some theories that try to explain it. It is possible that the relationship is symbiotic, as the tuna are most active during the day and the dolphins are most active during the night, so one group can rest while the other group feeds. A similar relationship is seen between spinners and spotters.

Regardless of the reason, the fact that the three species school together allows the tuna fishermen to find schools of tuna very easily. In 1959, they discovered this relationship and began to exploit it. Fishermen look for a commotion on the horizon, indicating feeding seabirds, leaping dolphins, or both, and could indicate the presence of tuna Since spinners and spotters aggregate in the thousands, schools are not difficult to see even at a distance. When the tuna boat is in range, speedboats known as pongas are lowered and herd the school together. When the animals are compactly herded, the seiner lowers the net and surrounds the herd, trying to trap both dolphins and tuna. At first, the purse seine is about 1.6 km long and open, forming a wall. It is also open at the bottom, but herded individuals do not go under it to escape, probably because the water at a depth of 200 meters is too cold. The pongas continue to roar around the perimeter, making another barrier. When the dolphin school is completely surrounded, it is pursed, that is, it is closed at the bottom using a cable that passes through a series of rings. Every creature in the school is trapped. The net is then drawn onto the boat through a power block, the one invention that made this kind of fishing possible. Captured individuals are stacked methodically on the deck as the enclosure shrinks.

Dolphin Behavior in the Nets

Further compounding the problem is the fact that spinners and spotters tend to be timid, easily frightened, and fearful of objects. They depend on the presence of other dolphins and do not react well to new situations. As a result, they tend to react to the purse seines by panicing rather than by attempting to escape as they easily could given their acrobatic abilities. The passive behavior of these animals is described as a form of “capture myopathy” and often leads to death. Although normally a factor that aids their survival, in the case of purse seines, their timid nature is deadly.

When not herded or chased, spinners and spotters swim slowly and spread over a long distance, often with between 20 and 30 body lengths between different individuals. When they are chased, they crowd together, leaving only 2 to 3 body lengths between them. They also move more quickly, making low leaps from the water, as it is the most efficient method of swimming. As the school is surrounded by the nets, various behavior patterns emerge. In a practice called milling, a large percentage of the school stays in one area, swimming and diving. Early in the set, there is some leaping, but that quickly subsides. In addition, some individuals start rafting, where a group hangs vertically in the water, head up. Individuals align themselves in layers, discrete bands oriented horizontally. Groups of four to five individuals make up each layer, and there may be up to four layers stacked vertically. After surfacing to breath, always return to their original position. Often some dolphins just passively sink slowly to the bottom of the nets, probably as a reaction to the stress from the boats, the noise, and the wake. This type of behavior is understandable considering that spinners and spotters are used to the open ocean where they have no barriers or confinement. Although spinners usually separate from the spotters in a net, they do exhibit similar behavior. However, spinners tend to move around more in the nets, and are located more in the periphery.


24-5.  Natural disasters are not manmade and cannot be controlled, yet after an event, there is generally global or at least national economic costs that result.  Do you think that global economic assistance is appropriate and of value in such cases and what role should government versus charitable contributions and organization play after such events?

24-6. What are potential problems with the marine aquarium trade?

24-7.    Exclusive Economic Zones also called EEZ and tend to extend 200 miles offshore  – what is the purpose of establishing these for a more industrialized nation versus and underdeveloped one?

24-8.   What is acidification of the ocean and what is the concern regarding it?

24 – 9.  How much of the world population relies on seafood as a major source of food?

24 – 10. What are some potential new drugs (pharmaceutical products) from the sea?

24- 11  download a guide from this site and find the best local place to get sustainable seafood.

24 – 12 How available and feasible is desalination to the USA? Is the use and availability of desalination techniques the same or different to other countries?


Dirty Water

Marine pollution deals with the effect of pollutants on the ocean environments, recognizing that there are both natural and human-generated materials involved and that the controlling factors are the amounts of these pollutants being introduced into the ocean and the ability of the ocean’s ecosystems to deal with them. Even where natural materials are involved, excessive amounts can be problematic. Depending on the types of pollutants involved and the characteristics of the ecosystem affected, cleanup or mitigation can be more damaging than the actual event.

Although oil spills tend to get the most attention, other types of pollution are also of concern. Synthetic chemicals are especially dangerous because they tend to resist natural degradation, remaining in the food web and working their way through the food chains to the higher trophic levels.

Eutrophication is a process that involves nutrients, either natural or introduced, that enter an ecosystem in excessive amounts, upsetting the natural balances of the system and causing certain organisms to grow and spread abnormally, often to the detriment of other species.

Coastal power plants contribute significant pollution through the disposal of waste heat energy, which can significantly affect nearshore ecosystems over a period of time. A new concern is exotic or introduced species that are introduced when ships fill their ballast tanks at their home ports, then discharge the ballast water at their destination port, transporting marine organisms into “foreign” waters, where they often overrun the resident species. Of even broader concern are the processes of ozone layer depletion and global warming.

 Dirty Water


25-1. List several manmade problems that affect the quality of the oceans for marine life and/or its aesthetic value?

25-2. How might a plastic grocery bag effect a sea turtle if it saw it floating by?

25-3. Discuss petroleum product effects on different forms of marine life. What is your assessment of the oil spill situations that arise periodically?

25-4. Is thermal pollution a potential problem for coastal invertebrates? How?

25-5. What impacts might global warming be having on the phytoplantonic food web of the epipelagic zone?

25-6.   Explain how synthetic organic chemicals may be biologically amplified (include what biomagnification is):



Hands On

This lesson explores some of the factors beyond the search for empirical truth that motivate oceanographers. Concentrating on global oceanographic initiatives the study guide and text readings encourage students to review, synthesize, and integrate some of the larger ideas from the course.

Oceanography is not just facts; it is also the processes used to discover them. Like all sciences, oceanography is a community process. It is fostered by cooperation, yet driven by competition.

Even the most well-established theories are open to re-interpretation if new, conflicting evidence comes to light. Scientists are recognized as they add supporting evidence to strengthen existing theories, but immortalized if they make science abandon its most cherished paradigms and turn it on its head.

Global oceanography initiatives are allowing exploration of the oceans at an ever increasing rate at a time when the necessity to understand our global environment has never been more urgent. Projects such as GLOBEC, JGOFS, ODP, SeaWiFS, CLIVAR, TOGA, WOCE, and RIDGE are often multidisciplinary, interagency, and international and are the bridges between twentieth and twenty-first century oceanography. There are many others just beginning, on the drawing board, and as yet unimagined. The voyage is, indeed, endless.

Hands On

26 -1  Do you feel that after this course you have a more informed background to vote on critical legislation and be proactive in managing our global oceanic resource?

26 – 2.   Of the technologies and area we have explored in this course, what are three types of ocean exploration or research you feel would merit  the most future effort and why?



Use the order calculator below and get started! Contact our live support team for any assistance or inquiry.