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Ocean Facts

Jacques-Yves-Cousteau “The sea, once it casts its spell, holds one in its net of wonder forever.” -


Rachel Carson “It is a curious situation that the sea, from which life first arose, should now be threatened by the activities of one form of that life. But the sea, though changed in a sinister way, will continue to exist: the threat is rather to life itself.” –

Rachel Carson

Daniel Pauly “If we don’t manage this resource, we will be left with a diet of jellyfish and plankton stew.” -

Daniel Pauly

Oceans (from Ancient Greek Ὠκεανὸς or Okeanos, the great river) cover 71% of our planet (~3.6x108 km2) and represent over 95% of the biosphere. In Indian literature the term “ocean” is known by the term “Samudra” which literally means the "gathering together of waters" (saṃ- meaning "together" and -udra meaning "water").

The total volume is approximately 1.3 billion cubic kilometres, with an average depth of 3790 metres. In the context of Earth, it refers to one or all of the major divisions of the planet's World Ocean – they are, in descending order of area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic oceans. The word "sea" is often used interchangeably with "ocean", but a sea is a body of saline water possibly a division of the World Ocean) in a more inland location.

In fact, the widest variety of life forms is found in the ocean, not on land. There is no place in the ocean where life is absent. Oceans account for over ninety-five per cent of its life-supporting space. Ocean is the habitat of 250,000 known species, however much of the ocean's depths remain unexplored and it is estimated that over two million marine species may exist. Life is simply impossible on earth without the oceans. Life on Earth began in the ocean and after 3.5 billion years the interactions between ocean and atmosphere makes life possible on Earth. Yet the general public know very little about oceans.

How oceans impact our lives?

As the principal component of Earth's hydrosphere, the world ocean is integral to all known life, forms part of the carbon cycle, and influences climate and weather patterns. Provision of food and medicines or the detoxification of pollutants and the recycling of nutrients are functions of the ocean which create value for human users. Such essentials are called ‘ecosystem goods and services’. These goods and services are ‘for free’ but require intact marine ecosystems: Coral reefs, sea weed ecosystems, mangroves, salt marshes, mud flats, estuaries, rocky shores, sandy beaches, sea mounts, abyssal plains and open oceans – each of these habitats contributes to the oceans’ ability to serve essential goods and services.

Water and its unique properties determine much of the Earth’s atmospheric conditions. It drives our local weather, and water vapour regulates temperature of Earth. Ocean currents greatly affect the Earth's climate by transferring heat from the tropics to the polar regions, and transferring warm or cold air and precipitation to coastal regions, where winds may carry them inland. Without the ocean, Earth would be intolerably hot during the day and frozen at night. The ocean absorbs and a store heat energy from the sun’s rays and redistributes it around the globe, affecting the movement, temperature and moisture content of air masses over sea and land.

Globally, life in our seas produces one third of the oxygen we breathe and human consumption of fish makes up 16% of our animal protein supply and is particularly important as a protein source for populations in developing countries. More than just a valuable source of food, the ocean is one of the largest natural reservoirs of carbon. It stores about over 15 times more CO2 than the terrestrial biosphere and soils, and plays a significant role in climate moderation Globally, the oceans have accumulated up to one third of the total CO2 emissions from burning fossil fuels, land use change and cement production within the last 250 years.

Genetic resources in the oceans and coasts are of great interest for commercial use. The value of such global “hot spots” of biodiversity like coral reefs is estimated to be over US$ 6,000 per hectare - with respect only to the development of drugs. Up to now, thousands of new biochemical have been discovered in marine organisms such as sponges, soft corals, molluscs, bacteria and algae, but only a small fraction of the marine organisms have even been documented Medicine from the sea is a comparably new chapter in pharmacology. The first agents from the Carribean sponge Tethya crypta were discovered in the fifties, and became the base of the antiviral substance ARA-A today used in five medications to fight herpes During the last decades a broad range of ‚drugs from the sea’ has been researched.

Marine bioprospecting is promising research: today, in fact, all new compounds from pharmacological research activities originate from the oceans - this sheds light on the potential of marine biotechnology. The conotoxine from the various species of cone snails alone represents more than 100 patents.

Bionics – a made-up word composed from biology and technics - helps us to improve our toolbox to solve problems using innovative materials, technologies and processes. Marine life provides a huge variety of examples and prototypes we can learn from. The attributes of natural materials like adaptive efficiency, multiple functions and economical use of resources are very valuable for the development of new materials. Nature shows us how composition and function can act together and how materials can emerge, transform and restore A lot of characteristics of the marine environment like pressure, resistance, darkness, temperature, chemical composition etc. have stimulated evolutionary processes and lead to highly creative solutions to this adversity.

Two-thirds of the world's human inhabitants live within 40 miles of the ocean. Sea grass meadows are protective nursery areas for many estuarine and ocean fish. Healthy estuaries are a rich source of nutrients and food organisms that support their own high productivity and that of adjacent coastal waters, and often supporting valuable fisheries as a result. Some coastal areas are abundant sources of larvae that are transported by currents to other areas where they replenish depleted populations -- which may include populations of commercially valuable shellfish. Marshes trap sediments and filter nutrients and chemicals from the water – a function that may help protect coastal waters from some of the pollution that humans allow to flow from the land. Coastal upwelling areas provide nutrients for highly productive food webs that support other sea life and humans. Coral reefs provide physical structure, food, and protection for a great diversity of marine species, and the coral itself is composed of carbonate which has been produced by animals and plants in a process that sequesters large quantities of carbon dioxide from the environment. In short oceans are so special to human beings. However, it is important to also appreciate that these functions are essential or useful to supporting a healthy ocean system in its entirety and contribute to the support of all life on earth.

Zones and depths

The ocean is divided into different zones depending on the present physical and biological conditions. The pelagic zone includes all open ocean regions, and can be divided into further regions categorized by depth and light abundance. The photic zone covers the oceans from surface level to 200 metres down. This is the region where photosynthesis can occur and therefore abounds with life. Since plants require photosynthesis, life found deeper than this must either rely on material sinking from above (the so called marine snow) or find another energy source; hydrothermal vents are the primary option in what is known as the aphotic zone (depths exceeding 200 m). The pelagic part of the photic zone is known as the epipelagic. The pelagic part of the aphotic zone can be further divided into regions that succeed each other vertically according to temperature. The mesopelagic is the uppermost region. Its lowermost boundary is at a thermocline of 12°C, which, in the tropics generally lies at 700–1000 metres. Next is the bathypelagic lying between 10 and 4°C, typically between 700–1000 metres and 2000–4000 metres. Lying along the top of the abyssal plain is the abyssalpelagic, whose lower boundary lies at about 6000 metres. The last zone includes the deep trenches, and is known as the hadalpelagic. This lies between 6000–11000 metres and is the deepest oceanic zone.

Along with pelagic aphotic zones there are also benthic aphotic zones. These correspond to the three deepest zones of the deep-sea. The bathyal zone covers the continental slope down to about 4000 metres The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. The hadal zone corresponds to the hadalpelagic zone which is found in the oceanic trenches. The pelagic zone can also be split into two subregions, the neritic zone and the oceanic zone. The neritic encompasses the water mass directly above the continental shelves, while the oceanic zone includes all the completely open water. In contrast, the littoral zone covers the region between low and high tide and represents the transitional area between marine and terrestrial conditions. It is also known as the intertidal zone because it is the area where tide level affects the conditions of the region.

A Changing Ocean

The ocean has long been widely viewed as limitless, immune to human activity. However, recent research show that the marine life is in danger as a result of ‘bad treatment’ by the human species. Some species, from the great auk to the sea mink, are extinct; others, notably the great whales, have been hunted to fractions of their original populations. Commercial overexploitation of the world’s fish stocks is so severe that almost a third of all fish stocks are being over-exploited, and some 13 percent have collapsed completely. Between 30 and 35 percent of the global extent of critical marine environments such as seagrasses, mangroves and coral reefs are estimated to have been destroyed. The main threats to oceans include unscientific developmental activities in coastal zone, pollution, over exploitation, eutrophication, invasive species and climate change.

Future Directions

The complexity of marine environments and the limitations of our ability to predict ecosystem responses often handicap conservation of marine environment and the biodiversity therein. However, three are rays of hope. Around the world, species and populations are recov¬ering with effort and intervention from communities and governments; large areas are being established as protected areas; and the Parties to the Convention on Biological Diversity (CBD) have adopted a series of specific targets that require stakeholders at all levels to work together to protect the biodiversity that lives in the ocean, for its own sake and for the benefits it brings to people worldwide.

Currently only 0.6 percent of the world’s oceans have been designated as Marine Protected Areas (MPAs) - compared to almost 13 percent of our planet’s land area - and the vast majority suffer from little or no management at all. To make the conservation effective, our primary concern should be to know about oceans. Providing sound scientific assessments is a key element of the conservation of regional Seas as they provide an important tool for policy makers to make informed decisions that ultimately affect the livelihoods of thousands of people whose livelihood is intricately linked with the health of the oceans.

Let us spread the message of the oceans. They need our support; in turn we are the major beneficiaries!

Learn More

International Collective in Support of Fishworkers (ICSF) -
Biodiversity Conservation Network -
Bioprospecting Information Resource -
Coastal Wiki -
Fisheries and Aquaculture Department -
International Maritime Organization -
The Nature Conservancy—Freshwater Conservation -
Ocean Classroom Foundation-
Pacific Regional Environment Programme -
The World Ocean Observatory -
International Coral Reef Initiative -
United Nations Convention on the Law of the Sea -
Convention on Biological Diversity-