Introduction to Ocean Sciences

Chapter 2: History and Challenges of Ocean Studies

Guide to Reading and Learning

Many of you reading this chapter will have had little or no personal experience with the oceans except perhaps for a visit or two to the coast. Also, many will have had little exposure to the history of human use, exploration, and study of this area that covers two thirds of our planet. There is good reason for this. The oceans are an environment that is not part of our natural habitat. It is a changeable, sometimes dangerous environment for humans, and throughout history the vast expanses of the oceans have been used somewhat uneasily by humans seeking mainly food and safe passage from one coast to another. Recreational uses, except for the esthetic pleasures of watching the oceans from land, are a very recent development in human history. Thus, exploration and study of the oceans has lagged many centuries behind human explorations and scientific studies of the land and terrestrial ecosystems.

In this chapter we start by reviewing the history of ocean exploration and the use of the oceans as a means of transportation for colonization and trade. Perhaps you will be surprised that this was almost all of the study that humans did on the oceans until a little more than 200 years ago. Perhaps you will be surprised that ocean scientists can precisely date the first systematic scientific studies of the oceans to the year 1872. Did you know that a group of 243 men lived and worked from December 1872 until May 1876 on a sailing vessel that was only about three-quarters of a football field long and only a few meters wide? Their small vessel, the Challenger, was crammed from stem to stern with scientific sampling and measurement equipment. They sailed more than 127,000 km around the world at a top speed of no faster than a bicyclist can sustain, performing the first systematic studies of the oceans. They did so in an age before practical electricity and the electric light was invented.

After the Challenger expedition, study of the oceans developed at an ever more furious pace. In this chapter, we have the opportunity to review the highlights of the many discoveries and technological developments that have led to the sophisticated methods that we now use to study the oceans. Yet even today those studies are performed in an environment that is in many ways much more difficult for scientists to study than the surface of the moon or Mars. At the end of this chapter we examine the reasons why the oceans are so difficult to study. As you read this material, think about how much more difficult it must have been for the early oceanographers, who not only had to contend with these difficulties but who did so without the scientific instruments, modes of communication, and personal comforts that we now have from electricity.

Chapter 2 Essential to Know 

Critical Concepts used in this chapter

CC.10

2.1 What Is Oceanography?

  • Oceanography has only recently developed from mapping the oceans to a much more comprehensive suite of ocean sciences.
  • Physical, chemical, geological, and biological processes in the oceans are all intimately linked and interdependent. As a result, oceans sciences must be interdisciplinary.

2.2 Exploration and Mapping

  • All early ocean studies were focused on mapping to facilitate travel and trade.

Prehistory

  • Evidence indicates that marine fishes were caught and eaten by early humans about more than 40,000 years ago.
  • Evidence exists that boats, fishhooks, and nets were used 8,000 year ago (and probably earlier).
  • Primitive boats were probably made of animal skins, tree bark reeds, and wood—all of which decompose relatively quickly—so, although no direct archaeological evidence has been found, boats have probably existed for many tens, perhaps hundreds, of thousands of years.

Ocean Exploration in Early Civilizations

  • The first recorded systematic studies of the oceans were centered in the Mediterranean Sea and Polynesia and Micronesia in the Pacific Ocean.

The Mediterranean

  • Centered on the island of Crete about 3000 bce, the Minoans are considered the first recorded civilization to use boats extensively for transport, trade, defense, and conquest.
  • Seafaring continued to develop in ancient Greek and Egyptian civilizations, but the Phoenicians, who lived in parts of what are now Israel, Lebanon, and Syria between about 1100 bceand 850 bce, were the next great sea power. They journeyed to Spain, Italy, North Africa, the British Isles, and perhaps even around the entire African continent. 
  • The earliest crude maps of coastlines were made several thousand years ago.
  • The earliest known detailed and generally accurate map was a rendering of the Mediterranean drawn by the Greek Herodotus in 450 bce.
  • Ptolemy, another Greek, who lived around 150 ce, was the most famous early mapmaker. His maps were the basis for all maps until the 1500s. Ptolemy’s maps were accurate in their north–south dimensions but were not accurate in their east–west dimensions because north–south distances could be measured by observing star positions whereas east–west directions could not be measured this way. These errors in east–west distances were only corrected in the 1760s when chronometers that could work at sea were developed. 
  • The Greeks made many other observations about the Earth and oceans. For example, Pythagoras declared that the Earth was spherical, Aristotle concluded that total evaporation must equal total rainfall, Pytheas proposed that tides were caused by the moon, and Eratosthenes calculated the correct value of the Earth’s circumference. Poseidonius later recalculated this circumference incorrectly and his error, included in Ptolemy’s maps, was not corrected until after Columbus rediscovered America.

Micronesia and Polynesia

  • About 4,500 years ago the large islands of the far west Pacific Ocean and Micronesia were colonized, and from there about 1,000 years later the Polynesians, colonized the western and central Pacific islands. The Polynesians also later colonized the Pacific as far south as New Zealand, as far north as Hawaii, and as far east as Easter Island.
  • Polynesians used double-hulled catamarans, a design still in use due to its stability in high seas. They navigated using knowledge of the stars, winds, wave patterns, clouds, and seabirds that was unwritten but passed down by generations of navigators.

The Dark Ages and the New Era of Discovery 

  • There was little exploration or study of the oceans for centuries during the Dark Ages. However, in the mid 1400s a new wave of European exploration and systematic mapping of the oceans began.
  • Captain James Cook voyages between 1768 and 1780 are considered the first systematic exploration, study, and mapping of the oceans. Cook sailed into almost all the regions of the world’s oceans, mapping and making observations including ocean depths, water temperature, and wind speed and direction.
  • At about the same time Benjamin Franklin’s observations allowed him to identify and map the Gulf Stream.

The Birth of Oceanography

  • By the early 1800s several nations had agencies dedicated to mapping the oceans to facilitate safe navigation and trade.

The Beagle

  • In 1831–1836, Charles Darwin sailed as the naturalist aboard the Beagle on a hydrographic survey of the tip of South America. On this voyage he developed his famous theory of evolution, but also observed marine fossils high in the Andes Mountains. He concluded that this discovery meant that the continents were not fixed and unchanging as geologists then believed. Darwin also proposed a theory of formation of coral atolls that reflects our current understanding of the process.   

The Challenger

  • The first expedition mounted purely to study the oceans themselves, rather than to map them, was the voyage of the Challenger in 1872–1876. Challenger sailed around the world and collected observations of water temperature, both at the surface and at depth; current velocities; meteorological data; soundings of ocean depths to more than 8000 m; samples of seafloor sediments; samples of fishes and other organisms; and visual observations of birds and mammals.
  • Because systematic ocean studies began with the Challenger in 1872 they have been underway for only a little more than a century.

The Modern Era

  • Since the Challenger expedition there has been intensive study of the oceans supported by many technological advances and resulting in many sometimes-surprising discoveries
  • Major advances in technologies that have benefited ocean sciences include scuba and submersibles, remotely operated and autonomous instrument packages, satellites, and computers.
  • Major revelations of ocean science studies include the first detailed seafloor map of the world in 1959, the discovery of hot brines at the bottom of the Red Sea in 1964, the discovery of chemosynthetic communities at hydrothermal vents in 1977, the growing understanding of plate tectonics and the many observations that led to the acceptance of the plate tectonic theory, and the major revelations of ocean complexity that came to light when the first satellites made synoptic measurements of ocean processes possible.

2.3 Difficulties of Studying the Ocean Environment

  • For several reasons, the oceans are more difficult to study than terrestrial systems and even the moon.

“Seeing” through Ocean Water       

  • Ocean water absorbs electromagnetic radiation very effectively so we cannot see through it. Almost none of the remote sensing tools used to study the surface of the Earth, moon, and planets can see beyond a few meters into the ocean waters. Radio, radar, light, and all other electromagnetic radiation is absorbed by water. Only gravity, sound, and magnetic fields pass easily through ocean waters.

Inaccessibility

  • The oceans are deep—an average of 3.8 km—so most of their volume and sea floor is remote from areas where humans live or can visit easily. Lowering instruments to the seafloor and retrieving them can take many hours. Ships that carry researchers to study the oceans travel only slowly and are costly to build and operate. Navigation at sea was difficult until the relatively recent development of satellite-based GPS navigation systems, and GPS does not work underwater.

Pressure

  • Pressure increases very rapidly with depth—approximately 1 additional atmosphere of pressure for every 10 m of depth. While spacecraft experience a 1 atmosphere pressure change, instrument packages and submersibles must endure an increase of more than 1000 atmospheres of pressure to reach the deep-sea floor.

Conductivity, Corrosion, and Fouling

  • Ocean water is electrically conductive and corrosive. As a result all electronic equipment used in the oceans must be contained in sealed waterproof housings (unlike instrument in unmanned satellites, which can be safely exposed to space), and corrosion and fouling by organisms such as barnacles makes it very difficult to deploy instruments in the oceans for any extended period of time.

Wave Motion

  • The ocean surface is dynamic. This means that seasickness and fatigue a problem for many ocean scientists and makes it difficult and dangerous to handle equipment needed to deploy and retrieve instruments and samplers. The constant vibration and pounding experienced on a research ship in rough weather renders some scientific instruments completely unusable, and almost all instruments and computers need to be specially modified or designed specifically to operate reliably in this environment. All lab equipment and other instruments must be secured so they are not thrown about  by the vessel’s movement.

Logistics

  • The logistics of working far from land on a research vessel are difficult. If instruments or equipment fail, they must be repaired on site with available parts and by the personnel on board. Equipment cannot be taken to a repair shop and spare parts cannot be obtained if they are not already carried on the research vessel.

 

Critical Concept Reminders:

CC.10 Modeling (p. 24)

  • Complex environmental systems including the oceans and atmosphere can best be studied by using conceptual and mathematical models. Many oceanographic and climate models are extremely complex and require the use of the fastest supercomputers. To read CC10 go to page 26CC.

 

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