2.5: Chapter Summary

What Is Oceanography? 

Oceanography is an interdisciplinary science divided into subdisciplines of physical, chemical, geological, and biological oceanography.

Exploration and Mapping. 

The oceans have been used for fishing for more than 100,000 years. Systematic ocean exploration began between about 6000 and 2000 years ago and was concentrated in the Mediterranean, Polynesia, and Micronesia. Subsequently, between about 2000 and 600 years ago, exploration apparently slowed for centuries, except in the Mediterranean.

After about 1400 CE, European and Mediterranean nations mounted many ocean expeditions, and the scientific study of the oceans burgeoned. The voyages of Captain Cook (1768–1780), Charles Darwin and the Beagle (1831–1836), and the Challenger (1872–1876) conducted some of the most important early systematic oceanographic studies.

Law of the Sea. 

For most of recorded history, the resources of the oceans were not owned and could be exploited by anyone. In 1672, the British claimed ownership of a territorial sea that reached 5.6 km offshore. Such claims became common practice until 1945, when President Truman claimed U.S. ownership of the resources of the seafloor offshore to where the ocean reached a depth of 183 m. Many similar claims by other nations ensued. The resulting confusion was resolved by United Nations “Law of the Sea” conferences in 1958 and 1960, and passage in 1982 of a comprehensive Law of the Sea Treaty after more than a decade of negotiations.

The Law of the Sea Treaty grants ownership of all fisheries and mineral resources within an EEZ that is 200 nautical miles wide offshore from each coastal state. The most controversial treaty provisions apply the principle that minerals of the deep-ocean floor outside of EEZs are the “common heritage of mankind.” The U.S. and several other nations did not sign the treaty because of these provisions. In 1994, enough nations ratified the treaty for it to become effective, and the U.S. signed it but has not yet ratified it.

The seabed and fishery resources of an EEZ can be very valuable. Consequently, sovereign nations now consider otherwise inconsequential islands valuable. The result has been a variety of territorial disputes, and even wars, over such islands.

In 2023, an addendum to the Law of the Sea Treaty, generally referred to as the “Treaty of the High Seas,” was adopted. This Treaty ensures that the benefits of marine genetic resources (e.g. drugs produced from marine animals) are shared under the “common heritage of mankind” principle; establishes rules for conducting impact assessments in the high seas; and establishes a framework for the establishment of ocean sanctuaries within which area fishing will be prohibited. 

Value of Ocean Resources. 

The oceans provide abundant resources, including fisheries and other biological resources; transportation, trade, and military use; offshore oil and gas; methane hydrates; minerals and freshwater; recreation, aesthetics, and endangered species; energy; and waste disposal.

Biological Resources. 

Most of the world’s major fisheries are overfished. The principal reason is that most fisheries are an unowned resource open to anyone who wants to exploit them. Many fishing techniques collect and kill nontarget species that are often discarded. Bottom trawling also severely damages slow-growing seafloor ecosystems. Fishing line, nets, and other items are discarded or lost and cause beach pollution. Aside from fisheries and the aesthetic value of marine species, ocean biological resources include ornamental species used in aquariums, and pharmaceuticals extracted or developed from marine species.

Transportation, Trade, and Military Use. 

Most goods traded by humans are transported in surface vessels. The oceans are also extensively used by surface vessels and submarines of the world’s navies. Research to support naval uses, especially hiding and hunting submarines, has been critical to the development of oceanography. Recreation on cruise liners and small craft is increasing rapidly. Occasional spills, especially from oil tankers, releases of oil from boat motors and ship engines, dumping of trash by some vessels on the high seas, construction of ports and portside facilities, discharge of bilge water, antifouling paints, anchors, and dredging to maintain navigation channels each have environmental effects, often deleterious.

Offshore Oil and Gas. 

Most undiscovered oil is beneath the continental shelves and slopes. Offshore drilling and production platforms or islands are used throughout the world. These facilities have, on a few occasions, accidentally spilled large amounts of oil, and some of them discharge drilling muds and oily water.

Methane Hydrates. 

Large accumulations of methane hydrates have been discovered in ocean sediments, especially on the continental slope. Because methane burns cleanly, methane hydrates could provide a large and desirable source of energy. Several nations are now testing technological means for extracting the methane economically. Environmental impacts are uncertain but could include accidental release of methane (a greenhouse gas) and disturbance of continental slope sediments that could cause turbidity currents and tsunamis.

Minerals and Freshwater. 

Ocean mining for sand and minerals, although limited, is increasing. Mining alters habitat at the mine site and may lead to the discharge of tailings and other wastes. Coastal wetlands in some areas have been altered to construct evaporation ponds for salt production. Freshwater production from seawater generally discharges high-salinity brines.

Recreation, Aesthetics, and Endangered Species. 

Human populations have historically been concentrated on the coast for its aesthetic values and moderation of climate. These values are becoming increasingly important as human use of the oceans for many forms of recreation increases. Humans and their recreational activities have many effects on the marine environment that are becoming better studied and understood. The protection of ocean ecosystems and species has emerged as an important goal, but difficult conflicts often occur between the need for protection and the need for resources.

Energy. 

Winds, waves, tides, currents, and the temperature difference between surface and deep waters are all potential sources of energy. So far, only tidal energy is commercially developed. Facilities to generate energy from these sources may alter current, wave, and habitat characteristics and cause contamination from antifouling paints. OTEC may be the most promising technology, particularly for tropical island communities and is now in use in several locations outside the U.S.

Waste Disposal. 

The oceans are capable of assimilating large quantities of some wastes without any significant negative impacts. Wastes have been disposed of in the oceans for thousands of years, but increasing amounts have caused significant negative impacts on the ocean environment, especially when dumped or discharged in locations or by means that allow them to accumulate locally. Except for dredged material, most wastes now disposed of are liquids or slurries, such as treated sewage.