My Science School

The Arctic Ocean, which is the smallest of the world's oceans, lies close to the North Pole. Along with its marginal seas the Chukchi, East Siberian, Laptev, Kara, Barents, Greenland, and Beaufort, the Arctic Ocean has the least-known basins and bodies of water in the world's oceans due to its remoteness, difficult weather, and perennial or seasonal ice cover.

About four million people live in the Arctic region. Many of them are indigenous groups that have thrived in this harsh climate for hundreds of years. They rely mostly on the ocean resources for surviving this harsh climate and generate livelihood through these activities. Fishing, sealing, whaling, and other activities are their livelihood means. The U.S., Canada, Greenland, Iceland, Norway, and Russia all have territories that reach into the Arctic Ocean.

The Arctic Ocean is in the news these days because of its effects on global warming. Rising temperatures in the Arctic are expected to cause large amounts of fresh melt-water to enter the north Atlantic, an event that will possibly disrupt global ocean current patterns. This will lead to drastic changes in the Earth's climate. When the extent of sea ice diminishes and the sea level rises, the effect of storms (such as the Great Arctic Cyclone of 2012) on open water increases. Reduced sea ice also leads to increased human-animal conflicts. It will, for example, cause polar bears to search for new sources of food, forcing them to move into human territories. Since December 2018, the archipelago of Novaya Zemlya has been under a mass invasion of polar bears, and in February 2019, a state of emergency was declared there. Dozens of polar bears were entering homes, public buildings, and inhabited areas in search of food. All this led to the Arctic Ocean being in the news.

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The Mariana Trench is not only the deepest oceanic trench on Earth but also holds the two lowest points on the planet. This crescent- shaped trench is located in the Western Pacific, east of the Mariana Islands near Guam. The region around the trench is known for many unique environments, such as vents bubbling up liquid sulfur and carbon dioxide, active mud volcanoes, and marine life adapted to pressures 1,000 times more than at sea level.

The Challenger Deep, the southern end of the Mariana Trench, is the deepest spot in the ocean. The National Oceanic and Atmospheric Administration, in 2010, used sound pulses sent through the ocean and calculated the Challenger Deep to be 10,994 metres deep even though it was considered almost impossible to measure its depth. In 2021, pressure sensors were used to calculate its depth and it was discovered that the deepest spot in Challenger Deep was 10,935 m. The ocean's second-deepest place is also in the Mariana Trench. The Sirena Deep, which lies 200 kilometres to the east of Challenger Deep, is 10,809 metres deep.

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The longest species of seaweed is the giant kelp Macrocystis pyrifera. It is found near the Californian shore and in different parts of the world near the Pacific Ocean. The longest specimen that has been verified is 60 metres long but unofficial reports say that even longer specimens have been found.

They form large and dense kelp forests, which become habitats for a number of different marine species. They are often located in cold and clear waters, where they resemble tall grass although they are not part of the grass family. It is a type of brown alga and belongs to the large kingdom of Protista. Since kelp is not a plant, it does not have roots and obtains its nutrients from a structure called a holdfast by which it attaches itself to the rocky bottom of the ocean. But kelp are similar to plants by the fact that they use photosynthesis to harvest the Sun's energy and do not feed on other organisms to keep themselves alive. They are also one of the fastest growing species and are known to grow up to 60 centimetres in a single day when given perfect conditions. Strikingly, when the kelp reaches the sea surface, it grows horizontally and floats as large mats that shade the water column and the sea floor below it.

The kelps also become a source of nutrition once they decompose in the sea bed. Sea otters even use these giant kelps to avoid being floated away while they sleep.

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The Great Barrier Reef covers an area of 348,000 square kilometres, and is the longest and largest reef complex of the planet. In fact, this remarkable site is one of the seven wonders of the natural world. Located on the north-east coast of Australia, the Great Barrier Reef is home to a huge diversity of species and habitats. This ecosystem is intricately interconnected, making it one of the richest and most complex natural ecosystems on earth.

It is home to over 1,500 species of fish, 400 species of corals, and 4,000 species of molluscs. It also hosts 240 species of birds along with a number of sponges, anemones, marine worms, crustaceans, and other species. This giant marvel is also home to many endemic and threatened species listed by the International Union for Conservation of Nature (IUCN). These features make it a very popular tourist destination and thus contribute to the economic development of the country.

In order to safeguard and preserve the reef, it was declared as the Great Barrier Reef Marine Park in 1975, and the supervision of the park was handed over to the authorities of the Marine Park.

Owing to its significance in the ocean ecosystem, the Great Barrier Reef was added to UNESCO’s World Heritage List.

Picture Credit : Google