OCEANOGRAPHY: HISTORY, FIELD OF STUDY, BRANCHES AND RESEARCH - SCIENCE - 2025

The oceanography is the science that studies the oceans and seas in their physical, chemical, geological and biological. Knowledge of the oceans and seas is essential, since according to accepted theories the seas are the center of origin of life on Earth.

The word oceanography comes from the Greek okeanos (water that surrounds the earth) and graphein (describe), and was coined in 1584. It is used as a synonym oceanology (study of bodies of water), used for the first time in 1864.

Oceanographic vessel and autonomous vehicle, in Lorne, Scotland. Source: StifynTonna, from Wikimedia Commons

It began to develop from Ancient Greece with the works of Aristotle. Later, in the 17th century Isaac Newton carried out the first oceanographic studies. From these studies, various researchers have made important contributions to the development of oceanography.

Oceanography is divided into four main branches of study: physics, chemistry, geology, and marine biology. Taken together, these branches of study make it possible to comprehensively address the complexity of the oceans.

The most recent research in oceanography has focused on the effects of global climate change on the dynamics of the oceans. Likewise, the study of ecosystems present in marine trenches has been of interest.

History

The beginnings

From its very origin, the human being has had a relationship with the seas and oceans. His first approaches to understanding the marine world were practical and utilitarian, as it was a source of food and communication channels.

The sailors were interested in fixing the maritime routes by means of the elaboration of navigation charts. Likewise, in the beginning of oceanography it was of great relevance to know the movement of marine currents.

In the biological field, already in Ancient Greece, the philosopher Aristotle described 180 species of marine animals.

Some of the first oceanographic theoretical studies are due to Newton (1687) and Laplace (1775), who studied surface tides. Similarly, navigators such as Cook and Vancouver made important scientific observations in the late 18th century.

XIX century

The father of biological oceanography is considered to be the British naturalist Edward Forbes (1815-1854). This author was the first to carry out surveys of marine biota at different depths. Thus, I was able to determine that the organisms were distributed differently at these levels.

Many other scientists of the time made important contributions to oceanography. Among these, Charles Darwin was the first to explain how the atolls (coral ocean islands) originated, while Benjamin Franklin and Louis Antoine de Bougainville contributed to the knowledge of the sea currents of the North and South Atlantic respectively.

Mathew Fontaine Maury was a North American scientist considered the father of physical oceanography. This researcher was the first to systematically collect large-scale ocean data. Their data was obtained mainly from ship navigation records.

Mathew Fontaine. Source: Maury Brendann, via Wikimedia Commons

During this period marine expeditions began to be organized for scientific purposes. The first of these was that of the English ship HMS Challenger, led by the Scotsman Charles Wyville Thomson. This vessel sailed from 1872 to 1876, and the results obtained in it are contained in a work of 50 volumes.

Twentieth century

During World War II, oceanography had a great applicability to plan the mobilization of fleets and landings. From there came research on wave dynamics, sound propagation in water, coastal morphology, among other aspects.

In 1957 the International Geophysical Year was celebrated, which had great relevance in promoting oceanographic studies. This event was decisive in promoting international cooperation in conducting oceanographic studies worldwide.

As part of this cooperation, during 1960 a joint submarine expedition was carried out between Switzerland and the United States; the bathyscaphe (small deep-diving vessel) Trieste reached a depth of 10,916 meters in the Mariana Trench.

Bathyscaphe Trieste. Source: See page for author, via Wikimedia Commons.

Another important underwater expedition was carried out in 1977 with the United States submersible Alvin. This expedition made it possible to discover and study deep-sea hydrothermal meadows.

Finally, it is worth highlighting the role of Commander Jacques-Yves Cousteau in the knowledge and dissemination of oceanography. Cousteau directed the French oceanographic vessel Calypso for many years, where numerous oceanographic expeditions were carried out. Likewise, in the informative field, various documentaries were filmed that made up the series known as The Underwater World by Jacques Cousteau.

Field of study

The field of study of oceanography encompasses all aspects of the world's oceans and seas, including coastal areas.

The oceans and seas are physical-chemical environments that host a great diversity of life. They represent an aquatic environment that occupies about 70% of the planet's surface. The water and its extension, plus astronomical and climatic forces that affect it, determine its particular characteristics.

There are three great oceans on the planet; the Pacific, Atlantic and Indian. These oceans are interconnected and separate large continental regions. The Atlantic separates Asia and Europe from America, while the Pacific divides Asia and Oceania from America. The Indian Ocean separates Africa from Asia in the area near India.

Ocean basins begin on the coast associated with the continental shelf (submerged part of the continents). The platform area reaches maximum depths of 200 m and ends in a steep slope that connects with the seabed.

The ocean floor has mountains with an average height of 2000 m (ridges) and a central furrow. From here comes the magma coming from the asthenosphere (inner layer of the earth formed of viscous materials), which is deposited and forms the ocean floor.

Branches of oceanography

Modern oceanography is subdivided into four branches of study. However, the marine environment is highly integrated and therefore oceanographers manage these areas without becoming overly specialized.

Physical oceanography

This branch of oceanography studies the physical and dynamic properties of water in oceans and seas. Its main objective is to understand ocean circulation and how heat is distributed in these bodies of water.

Take into account aspects such as temperature, salinity, and the density of the water. Other relevant properties are color, light and the propagation of sound in the oceans and seas.

This branch of oceanography also studies the interaction of atmospheric dynamics with water masses. In addition, it includes the movement of ocean currents at different scales.

Chemical oceanography

It studies the chemical composition of marine waters and sediments, the fundamental chemical cycles and their interactions with the atmosphere and the lithosphere. On the other hand, it addresses the study of the alterations produced by the addition of anthropic substances.

Likewise, chemical oceanography studies how the chemical composition of water affects the physical, geological and biological processes of the oceans. In the particular case of marine biology, it interprets how chemical dynamics affects living organisms (marine biochemistry).

Geological oceanography or marine geology

This branch is responsible for the study of the oceanic substrate, including its deepest layers. The dynamic processes of this substrate and their influence on the structure of the seabed and coasts are addressed.

Marine geology investigates the mineralogical composition, structure and dynamics of the different oceanic layers, especially those related to submarine volcanic activities and the subduction phenomena involved in continental drift.

The investigations carried out in this field allowed to verify the approaches of the theory of continental drift.

On the other hand, this branch has an extremely relevant practical application in the modern world, due to the great importance it has for obtaining mineral resources.

Geological prospecting studies on the seabed are allowing the exploitation of offshore fields, particularly natural gas and oil.

Biological oceanography or marine biology

This branch of oceanography studies marine life, therefore it encompasses all branches of biology applied to the marine environment.

The field of marine biology studies both the classification of living beings and their environments, their morphology and physiology. In addition, it takes into account the ecological aspects relating this biodiversity with its physical environment.

Coral reef in the Andaman Islands (India) Ritiks, from Wikimedia Commons

Marine biology is divided into four branches according to the area of ​​the seas and oceans that you study. These are:

• Pelagic oceanography: it focuses on the study of ecosystems present in open waters, far from the continental shelf.
• Neritic oceanography: living organisms present in areas near the coast, within the continental shelf, are taken into account.
• Benthic oceanography: referred to the study of the ecosystems found on the surface of the seabed.
• Demersal oceanography: living organisms that live near the seabed in coastal areas and within the continental shelf are studied. A maximum depth of 500 m is contemplated.

Recent research

Physical oceanography and climate change

Recent research includes those evaluating the effects of global climate change on ocean dynamics. For example, it has been found that the main ocean current system (the Atlantic current) is altering its dynamics.

It is known that the system of marine currents is generated by differences in the density of water masses, mainly determined by temperature gradients. Thus, hot water masses are lighter and remain in the superficial layers, while cold masses sink.

In the Atlantic, warm water masses move north from the Caribbean by the Gulf Stream and as they move north they cool and sink, returning to the south. According to the editorial of the journal Nature (556, 2018), this mechanism has slowed down.

It is suggested that the deceleration of the current system is due to the thawing caused by global warming. This causes the supply of fresh water to be greater and the concentration of salts and density of the water is altered, affecting the movement of water masses.

The flow of currents contributes to the regulation of world temperature, distribution of nutrients and gases, and their alteration has serious consequences for the planetary system.

Chemical oceanography

One of the lines of research that currently occupies the attention of oceanographers is the study of the acidification of the seas, mainly due to the effect of the pH level on marine life.

The levels of CO ₂ in the atmosphere have increased sharply in recent years due to the high consumption of fossil fuels by various human activities.

This CO ₂ dissolves in seawater, generating a decrease in the pH of the oceans. The acidification of the oceans is negatively affecting the survival of many marine species.

In 2016, Albright and colleagues conducted the first ocean acidification experiment in a natural ecosystem. In this research it was found that acidification can reduce the calcification of corals by up to 34%.

Marine geology

This branch of oceanography has investigated the movement of tectonic plates. These plates are fragments of lithosphere (rigid outer layer of the Earth's mantle) that move over the asthenosphere.

Recent research, by Li and colleagues, published in 2018, found that large tectonic plates can originate from the fusion of smaller plates. The authors make a classification of these microplates based on their origin and study the dynamics of their movements.

Furthermore, they find that there are a large number of microplates associated with Earth's large tectonic plates. It is indicated that the relationship between these two types of plates may help to consolidate the theory of continental drift.

Biological oceanography or marine biology

In recent years, one of the most striking discoveries in marine biology has been the presence of organisms in marine trenches. One of these studies was carried out in the trench of the Galapagos Islands, showing a complex ecosystem where numerous invertebrates and bacteria are present (Yong-Jin 2006).

Marine trenches do not have access to sunlight given their depth (2,500 meters above sea level), so the trophic chain depends on autotrophic chemosynthetic bacteria. These organisms fix CO ₂ from hydrogen sulphide obtained from hydrothermal vents.

Macroinvertebrate communities that inhabit deep waters have been found to be highly diverse. In addition, it is proposed that the compression of these ecosystems will provide relevant information to elucidate the origin of life on the planet.

References

1. Albright et al. (2017). Reversal of ocean acidification enhances net coral reef calcification. Nature 531: 362-365.
2. Caldeira K and ME Wickett (2003) Anthropogenic carbon and ocean pH. Nature 425: 365–365
3. Editoral (2018) Watch the ocean. Nature 556: 149
4. Lalli CM and TR Parsons (1997) Biological oceanography. An introduction. Second edition. The Open University. ELSEVIER. Oxford, UK. 574 p.
5. Li S, Y Suo, X Lia, B Liu, L Dai, G Wang, J Zhou, Y Li, Y Liu, X Cao, I Somerville, D Mu, S Zhao, J Liu, F Meng, L Zhen, L Zhao, J Zhu, S Yu, Y Liu and G Zhang (2018) Microplate tectonics: new insights from micro-blocks in the global oceans, continental margins and deep mantle Earth-Science Reviews 185: 1029–1064
6. Pickerd GL and WL Emery. (1990) Descriptive physical oceanography. An introduction. Fifth enlarged edition. Pergamon Press. Oxford, UK. 551 p.
7. Riley JP and R Chester (1976). Chemical oceanography. 2nd Edition. Vol. 6. Academic Press. London, UK. 391 p.
8. Wiebe PH and MC Benfield (2003) From the Hensen net toward four-dimensional biological oceanography. Progress in Oceanography. 56: 7–136.
9. Zamorano P and ME Hendrickx. (2007) Biocenosis and distribution of deep-sea mollusks in the Mexican Pacific: an evaluation of progress. Pp. 48-49. In: Ríos-Jara E, MC Esqueda-González and CM Galvín-Villa (eds.). Studies on Malacology and Conchiliology in Mexico. University of Guadalajara, Mexico.
10. Yong-Jin W (2006) Deep-sea Hydrothermal vents: ecology and evolution J. Ecol Field Biol. 29: 175-183.