Observed from space, our planet’s surface appears to be dominated by the color blue. This blue color occurs because of the presence of the oceans and seas of the world. These features cover approximately 71% or 361 million square kilometers (139 million square miles) of Earth’s surface with a volume of about 1370 million cubic kilometers (329 million cubic miles). The average depth of these bodies of seawater is about 3.8 kilometers (2.4 miles). Maximum depths can exceed 10 kilometers (6.2 miles) in areas known as ocean trenches. The oceans contain 97% of our planet's available water. The ocean is also home to many forms of life uniquely adapted to survive in this habitat. Humans have degraded the oceans and their life through pollution, overfishing, carbon dioxide acidification and resource exploitation.
A sea is commonly defined to be an extended body of saline water associated with one of the worlds five oceans (Atlantic, Indian, Pacific, Arctic, and Southern oceans). Some seas...
Marine microbesLast Updated on 2016-01-01 20:01:01
Marine microbes is a term that encompasses all microscopic organisms generally found in saltwater. Most micro-organisms are acellular and fall into the major categories of viruses, prokaryotes (bacteria), and protists, groups which differ considerably in biological characteristics. While representatives of these groups are found in virtually everywhere in marine waters, and they play nearly every ecological role imaginable, their most important function is that they form the base of the food chain in marine ecosystems.
Well-known to us as disease-causing agents, viruses are deceivingly simple organisms, little more than some nucleic acid within a protein container. They are 'parasitic particles' most about 40 nanometers in characteristic size. Viruses attach themselves to a living cell and inject a dose of nucleic acid into the cell; the injected nucleic acid... More »
Adriatic SeaLast Updated on 2015-09-29 15:00:08The Adriatic Sea is a branch of the Mediterranean Sea lying between 2 (50,590 miles2). The Adriatic has a maximum depth of 1233 metres (m) and an average depth of 252 m; although north of a line from Zadar, Croatia to Pescara, Italy, it is less than 100 m deep. The northern end of the sea is the Gulf of Venice and its southern limit is the Strait of Ontranto.
By European standards, the Adriatic is both warm (surface water temperature ranges from 8-13oC in winter to 22-25oC in summer) and low in turbidity; correspondingly, this sea is a popular tourist destination.
Map of the Adriatic Sea basin. Source: Norman Einstein/Wikimeia Commons
True-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2002. Source: NASA
The Adriatic coastline is heavily indented and includes many islands. As a result the coastline is... More »
Spratly IslandsLast Updated on 2015-06-01 15:45:31The Spratly Islands consist of more than 150 small islands or reefs scattered over a sea area of nearly 360,000 square kilometres in the South China Sea, about two-thirds of the way from southern Vietnam to the southern Philippines. The closest countries to the Spratly Islands are Malaysia, Vietnam, Brunei and the Philippines.
Abundant in marine biodiversity, the Spratly Islands lie in rich fishing grounds and potential gas and oil deposits. (See Energy profile of South China Sea)
These islands are strategically located near several primary strategic shipping lanes in the central South China Sea.
There are no indigenous inhabitants. But there are scattered garrisons occupied by military personnel of several claimant states, notably the Philippines.
They are claimed in their entirety by Taiwan, Vietnam and China, while portions are claimed by Malaysia and... More »
Madagascar mangrovesLast Updated on 2015-05-27 11:30:24
WWF Terrestrial Ecoregions Collection
Shielded from monsoon winds by the Central Highlands of Madagascar, Madagascar mangroves occupy a wide range of environmental and climatic conditions, and chiefly occur at the western coastline along the Mozambique Channel of the Indian Ocean. Although the ecoregion’s species richness is low, it is noteworthy in supporting certain endemic tree species; for example, thre are only 163 vertebrate taxa found in the entire ecoregion. The Madagascar mangroves are within the Mangroves biome of the Afrotropic Realm.
These mangroves also shelter highly diverse mollusk and crustacean communities, while capturing sediment that threatens coral reefs and seagrass beds. Dugongs, birds and sea turtles utilise mangroves, as do the native Malagasy people. Rice farming, shrimp aquaculture as well as stockpiling of... More »
Marine biodiversity and food securityLast Updated on 2015-02-28 19:05:44
Harvesting of wild fish and shellfish from the oceans provides food to the earth’s population, particularly in the developing world, and is a major contributor to the world economy. In the USA alone, fishing supports an industry worth nearly $50 billion annually. Although fishing commenced very early in human history, it was during the 20th century that its reach and impact spread around the globe and into deep waters, first with the advent of motorized vessels near the turn of the century, and later as a result of widespread availability of cheap oil, refrigeration, and increasingly effective technology. These developments made fishing an intensive global industry, particularly after Word War II. Modern fisheries, including both landings and by-catch, currently consume 24-35% of global marine primary production in the continental shelf and major upwelling areas,... More »
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