Definition Essay On Oceans

Long-Term Observations Hold Key to Climate Change Impact Assessment

Jan. 8, 2016 — Most ocean data sets are far too short for the accurate detection of trends resulting from global climate change, according to research. A new study will help to make decisions about where, and for ... read more

Nov. 10, 2017 — New research has revealed why the oldest water in the ocean in the North Pacific has remained trapped in a shadow zone around 2km below the sea surface for over 1000 ... read more

July 5, 2017 — While global ocean health has remained relatively stable over the past five years, individual countries have seen changes, according to a new ... read more

Nov. 24, 2015 — A remarkably detailed animation of the movement of the densest and coldest water in the world around Antarctica has been produced using data generated on Australia's most powerful supercomputer, ... read more

Mar. 16, 2017 — Marine biologists quantify the carbon consumption of bacterioplankton to better understand the ocean carbon ... read more

Acidification Affects the Ability of Bacteria to Clean Our Oceans

Jan. 12, 2016 — Marine bacteria are heavily influenced by the ongoing ocean acidification caused by human emissions of carbon ... read more

May 4, 2015 — Bacteria that feed on methane can control its concentration once it is released from the ocean floor. This can potentially stop the greenhouse gas from entering the atmosphere. But ocean currents can ... read more

Dec. 11, 2017 — Researchers have spotted the equivalent of smoke-rings in the ocean which they think could 'suck-up' small marine creatures and carry them at high speed and for long distances across the ... read more

Apr. 10, 2017 — New research has looked to the distant past -- all the way back to Earth's earliest oceans. A newly developed model suggests that the early oceans, right around the time that life originated, ... read more

Sep. 28, 2015 — A crucial process has been identified to explain the reason why dissolved organic carbon (DOC) levels in the deep oceans are constant despite a continuous supply from the surface ... read more

These vast bodies of water surrounding the continents are critical to humankind. But overfishing and global warming threaten to leave this vital habitat barren.

The ocean is a continuous body of saltwater that covers more than 70 percent of the Earth's surface. Ocean currents govern the world's weather and churn a kaleidoscope of life. Humans depend on these teeming waters for comfort and survival, but global warming and overfishing threaten to leave the ocean agitated and empty.

Geographers divide the ocean into four major sections: the Pacific, Atlantic, Indian, and Arctic. Smaller ocean regions are called seas, gulfs, and bays, such as the Mediterranean Sea, Gulf of Mexico, and the Bay of Bengal. Stand-alone bodies of saltwater like the Caspian Sea and the Great Salt Lake are distinct from the world's oceans.

The oceans hold about 320 million cubic miles (1.35 billion cubic kilometers) of water, which is roughly 97 percent of Earth's water supply. The water is about 3.5 percent salt and contains traces of all chemical elements found on Earth. The oceans absorb the sun's heat, transferring it to the atmosphere and distributing it around the world via the ever-moving ocean currents. This drives global weather patterns and acts as a heater in the winter and an air conditioner in the summer.

Sea Life

Life began in the ocean, and the ocean remains home to the majority of Earth's plants and animals—from tiny single-celled organisms to the blue whale, the planet's largest living animal.

Most of the ocean's plant life consists of microscopic algae called phytoplankton that float at the surface and through photosynthesis produce about half of the oxygen that humans and all other terrestrial creatures breathe. Seaweed and kelp are big algae easily visible to the naked eye. Marine plants with roots, like seagrasses, can only survive as deep as the sun’s rays can support photosynthesis—about 650 feet (200 meters). Nearly half of the ocean is more than 9,800 feet (3,000 meters) deep.

The deepest reaches of the ocean were thought to be devoid of life, but biological hotspots appear around places like hydrothermal vents and elsewhere in the deep sea. These chimney-like structures spew gases and mineral-rich water from beneath the Earth's crust. Tube worms, clams, and mussels gather around the vents to feed on heat-loving bacteria. Bizarre fish with sensitive eyes, translucent fangs, and bioluminescent lures lurk about in nearby waters.

Other fish, octopuses, squid, eels, dolphins, and whales ply the open waters while crabs, lobsters, starfish, oysters, and snails crawl and scoot along the ocean bottom. Creatures like jellyfish lack their own way to get around and are mostly left to the whim of the wind and currents. Mammals like otters, walruses, and even polar bears also depend on the ocean for their survival and dip in and out as their biology requires.

Colonies of polyps form coral reefs as they die. The reefs are mostly found in shallow tropical waters and are home to a brilliant mosaic of polyps, plants, and fish. Coral reefs are also visible victims of human activity. Global warming, siltation, pollution, and other phenomena are stressing the corals to death, and over-zealous fishers net more food than the reefs can restore.

Human Impact

Human activities impact nearly all parts of the ocean. Lost and discarded nets continue to lethally snare fish, seabirds, and marine mammals as they drift. Ships spill oil and garbage and transport critters to alien habitats unprepared for their arrival. Mangrove forests are cleared for homes and industry. More than half of the U.S. population lives in coastal areas, spilling garbage and sewage into the ocean. Fertilizer runoff from farms turns vast swaths of the ocean into dead zones, including a New Jersey-size area in the Gulf of Mexico. The greenhouse gas carbon dioxide is turning ocean waters acidic, and an influx of freshwater from melting glaciers threatens to alter the weather-driving currents.

Conservationists urge international protections to protect and replenish dwindling ocean fish stocks and reductions in greenhouse gases to curb global warming.

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