Why was the Arctic Ocean, the smallest of all oceans, in the news recently?

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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IS THERE UNDISCOVERED LIFE IN OCEANS?

So much of our oceans is still unexplored and remains a mystery. In fact, it is safe to presume we know more about the surface of Mars than about Earth's seafloors! But whatever  we little know of life in ocean depths is intriguing, fascinating, and incredible. The deep oceans are low on sunlight and plants but high on pressure, and yet, several creatures call this space home. Here's a glimpse of how they have adapted to life in unforgiving conditions.

Colours that help

 Since they dwell in open waters without plants or rocks to hide under to safeguard themselves from predators, many creatures benefit from disguise. Some of them are red. rendering them difficult to spot since red light does not penetrate those depths. Some others are transparent, again tough to spot. Many others are bioluminescent, a good tool to confuse predators.

Heard of sea snow?

Since ocean depths hardly have any plant, finding "live meal" is a tough task. Apparently, the duration between two live meals can be even up to three weeks for a marine creature! That's where marine snow or sea snow comes into play. When no live meal is available, the next best thing to turn to is the dead. Organic particles from the surface waters - disintegrated bodies of animals and plants, mingling with fecal matter-drift down in what is known as "marine snow".

What is chemosynthesis?

At the cracks between oceanic plates are hydrothermal vents - these are the hot springs on the ocean floor. These vents send out chemical compounds such as hydrogen sulphide. These chemical compounds are used for preparing food - much like sunlight is used in photosynthesis. This process used by microorganisms such as bacteria to create food (such as glucose), is called chemosynthesis.

Though humans still don't have a complete understanding of ocean depths, we're definitely leaving our mark there- and, sadly, not in a good way. With global warming, over-fishing, and pollution, we're changing the composition of the oceans they are acidifying, and hosting crustaceans with microplastics, as far deep as the Mariana Trench, the deepest location on Earth.

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WHY IS THE FORESTS OF THE MARINE WORLD UNDER THREAT?

A type of algae, kelp is crucial for thriving ecosystems the world over. However, kelp forests are shrinking. But, why? Let's find out

Most types of seaweed or marine algae grow along the coasts in shallow waters, where they can attach themselves to rocks, shells, or the sea floor. A root-like part called holdfast anchors them firmly and prevents them being washed away by strong waves or currents. A soft, flexible stem-like frond with outgrowths similar to leaves emerges from the holdfast. Though they carry out photosynthesis, algae are not plants as they don't have true roots, stems, leaves, or flowers. Marine algae can be green, brown, or red in colour. Red algae are delicate and feathery and prefer warm tropical seas. Small green algae are found everywhere in shallow waters. Brown algae called giant kelp grow in cool waters at depths ranging from 15 to 40 mt.

Extraordinary ecosystem

A kelp forest is one of the most valuable and productive: ecosystems on Earth. Kelp forests are found all over the world-the west coasts of North and South America, the southern tip of Africa and Australia, and off islands near Antarctica. In North America, kelp forests are found on the Pacific Coast from Alaska to California. A forest of kelp is home to a variety of creatures. They live and forage for food among its broad blades. The kelp provides shelter not only from predators. but also from storms. Mammals and birds that thrive in kelp forests include seals, sea lions, whales, sea otters, gulls, terms, egrets, and herons. Sea otters have an especially beneficial bond with kelp. Mother otters wrap their babies in kelp to keep them from drifting away while they go hunting. Adult otters also find the dense kelp canopies a secure place to snooze. The otters return the favour by eating sea urchins that dine on kelp. Kelp forests can shoot up in no time, growing up to 30 cm a day. Some species attain heights of over 45 mt!

Kelp farming is a big part of the billion-dollar global seaweed-farming industry. Kelp renders sea water less acidic. This enables kelp farmers to raise shellfish, which require low acidity. Kelp and mussels are grown on floating ropes, which also support baskets of scallops and oysters. One kelp farm can produce 40 metric tonnes of kelp and a million shellfish per hectare per year! As with other species of seaweed, kelp is used in many products,) including shampoos and toothpastes, as well as a wide range of foods such as salad dressings, puddings, cakes, dairy products, and ice cream. It is also employed in pharmaceuticals and in the manufacture of fireproof and waterproof textiles.

Urchin attack

The waters off the coast of northern California are home to lush forests of bull kelp. Since 2013, the population of purple sea urchins that feast on the kelp, has exploded, destroying almost 90 % of the kelp forest. Sea stars prey on purple urchins and keep their numbers in check. However, a mysterious disease killed off huge numbers of sea stars, leaving sea urchins to thrive. Sea snails (called red abalone) and red sea urchins, both of which are raised for meat and feed on bull kelp, died from starvation. Commercial red sea urchin and red abalone fisheries located on America's northwestern coast have closed down as a result.

Fact file

• Kelp forests are the ocean's lungs just as trees are the Earth's lungs. They absorb carbon dioxide and give out oxygen.

• Warming seas along the Australian coast have wiped out huge swathes of kelp forest.

•Extremely hot weather is harmful to kelp forests. Strong storms can wipe out large areas by uprooting the plants from the sea floor.

• There are 18 species of edible kelp, including kombu widely used in Japanese cuisine.

•Kelp is rich in calcium and Vitamin K.

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WHAT ARE CORAL REEF?

Important ocean habitats that offer us compelling evidence about the risks posed by climate change, coral reefs are large underwater structures made up of the skeletons of colonial marine invertebrates called coral. Also referred to as "the rain forests of the seas", scientists believe that one out of every four marine species live in and around coral reefs. This makes them one of the most diverse habitats of the planet, providing for a huge portion of Earth's biodiversity.

Each individual coral is referred to as a polyp. Coral polyps live on the calcium carbonate exoskeletons of their ancestors, adding their own exoskeleton to the existing coral structure. As the centuries pass, the coral reef gradually grows, one tiny exoskeleton at a time, until they become massive features of the marine environment.

Corals are found all over the world's oceans, from the Aleutian Islands off the coast of Alaska to the warm tropical waters of the Caribbean Sea. The biggest coral reefs are found in the clear, shallow waters of the tropics and subtropics. The largest of these coral reef systems, the Great Barrier Reef in Australia, is more than 1,500 miles long (2,400 kilometers).

Scientists have explored only about 20 percent of the ocean's floor, according to the National Oceanic and Atmospheric Administration (NOAA). As such, ocean explorers continue to discover previously unknown coral reefs that have likely existed for hundreds of years.

Most of the substantial coral reefs found today are between 5,000 and 10,000 years old, according to CORAL. They are most often found in warm, clear, shallow water where there's plenty of sunlight to nurture the algae that the coral rely on for food.

Coral reefs cover less than 1 percent of the ocean floor — all the reefs combined would equal an area of about 110,000 square miles (285,000 square km), only about the size of the state of Nevada. Nonetheless, they are among the most productive and diverse ecosystems on Earth.

About 25 percent of all known marine species rely on coral reefs for food, shelter and breeding. Sometimes referred to as "the rainforests of the sea" for their biodiversity, coral reefs are the primary habitat for more than 4,000 species of fish, 700 species of coral and thousands of other plants and animals, according to CORAL.

Coral reefs are typically divided into four categories, according to CORAL: fringing reefs, barrier reefs, patch reefs and atolls. Fringing reefs are the most commonly seen reef and grow near coastlines. Barrier reefs differ from fringing reefs in that they are separated from the coastlines by deeper, wider lagoons. Patch reefs typically grow between fringing and barrier reefs on the island platform or continental shelf. The rings of coral that make up atolls create protected lagoons in the middle of the oceans, typically around islands that have sunk back down into the ocean.

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IS THERE ANY UNDERWATER VOLCANO IN THE ISLAND OF MAYOTTE?

In 2018, seismometers around the world detected mysterious rumbles emanating from a usually quiet area in the Indian Ocean between Comoros and Madagascar. At the time, researchers were astonished to find a 2,690-foot-tall underwater volcano, which is about 1.5 times the height of the One World Trade Center in New York.

The volcano was formed after the largest underwater eruption ever detected and now, scientists suspect that the volcano draws its lava from the deepest volcanic magma reservoir known to researchers.

Scientists first took notice of volcanic activity about 31 miles east of the French island of Mayotte in 2018 when seismic hums, or low-frequency earthquakes, were detected by seismometers all over the globe. However, the huge underwater volcano shocked scientists because only two seismic events had been recorded near Mayotte since 1972. Before that, a layer of 4,000-year-old pumice in a lagoon nearby is the only additional evidence of an eruption ever found. After researchers noticed that the island was moving eastward about 7.8 inches a year, they installed ocean-bottom seismometers and GPS systems to track the island's fascinating geological activity. To understand the origin of the tremors that began in 2018, the study’s lead author Nathalie Feuillet, a marine geoscientist at the French National Center for Scientific Research, along with her team embarked on a mission—dubbed MAYOBS1—aboard the French research vessel Marion Dufrense in 2019.

Credit : Smith sonian magazine

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WHY IS THE ARCTIC AND ANTARCTICA ARE DIFFERENT?

Any mention of our polar regions - the Arctic and Antarctica - perhaps conjures up images of floating icebergs and blindingly white ice sheets. Sure, that's common to them but they are also different from each other in many ways.

The Arctic: A variety of landscapes and animals

Home to the North Pole, the Arctic lies in the Northern Hemisphere, and is the northernmost region of Earth. The Arctic usually refers to the area within the Arctic Circle, and spans the Arctic Ocean and parts of Scandinavia, Russia, Canada, Greenland, and Alaska (a U.S. State). It is not always covered in ice, and comprises mountains, rivers, lakes, hills, etc. It hosts several types of land animals and vegetation.

Antarctica: Just ice cover and barely any land animal

Our planet's southernmost continent, Antarctica is where the South Pole is situated. It is almost entirely covered in ice, and hardly has any vegetation or large rivers or lakes to boast of. With barely any land animals, the largest creature to dwell on land is a wingless insect that's about half an inch. There are hardly any trees there but Antarctica has its share of lichens, moss, algae, etc.

No penguins in the Arctic

Considering videos show glistening penguins diving into the water and launching themselves back on to ice-covered land adorably, it is easy to imagine that they inhabit both the polar regions. However, these flightless birds are found only in the Southern Hemisphere, and predominantly in Antarctica. None in the Arctic!

No polar bears in Antarctica

It is called a polar bear, after all, but the name is slightly misleading. It is an animal that lives in just one polar region - the Arctic. So, there are none in Antarctica. And, the next time someone asks you if polar bears hunt penguins in the wild, you can confidently tell them that can never happen because the two never get to meet each other!

A continent without permanent residents

Only a country can have permanent residents. And since Antarctica, though a continent, has no country, it has no permanent residents. It is not home to any indigenous community either. That does not mean Antarctica has just tourists. It hosts researchers and scientists at research stations set up by many countries for experiments, especially in summer. In winter, the numbers dwindle. Hard to imagine people queuing up to be a resident in a place with punishing temperatures! On the other hand, the Arctic does host permanent residents, especially indigenous groups, since it spans several countries. In fact, it has been inhabited for thousands of years.

Summers and winters

Due to the way our planet is tilted, the poles receive less light and heat from the sun than other regions of the world. The two seasons- summer and winter - are unique. Both the polar regions have long and cold winters and short summers. During summer, the poles have daylight since the sun does not set, and in winter, it is dark since the sun does not rise. However, since the Arctic and Antarctica are in the opposite directions, when one region experiences summer, the other experiences winter, and vice-versa.

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WHERE WAS THE RARE BABY GHOST SHARK FOUND?

The newly hatched, or neonate, ghost shark was found at a depth of 1200m off the east coast of New Zealand's South Island. The rare discovery of a juvenile ghost shark off New Zealand's South Island coast will help researchers better understand the biology and ecology of this mysterious deep water fish.

Ghost sharks or chimaeras are one of the most elusive fish species in the world. They have existed for hundreds of millions of years, but not much is known about them because they usually reside at depths of up to 2,000 metres. The neonate or hatchling was found at a depth of 1,200 metres.

Ghost sharks, also known as ratfish, spook fish or rabbitfish, are not actual sharks but are closely related to sharks and rays. They are cartilaginous, meaning their bodies have stiff armour-like plates and bone-like cartilage. Adult ghost sharks have venomous spines in front of their dorsal fins. Embryos grow inside their egg capsules on the sea floor and feed off the capsules until ready to hatch (between 6 to 12 months).

Critical missing details about the species' life cycle makes monitoring chimaera populations difficult. Sixteen per cent of all ghost shark species are threatened or near threatened.

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WHAT ARE THE FUN FACTS ABOUT BELUGA WHALES?

Beluga whales are white whales that live in the Arctic. They attract a lot of attention to themselves because of their unique color and the lack of a dorsal fin. Unfortunately, they are kept in captivity more than any other whale or dolphin species. Due to the irresponsible behavior of humans they are now on the edge of extinction. Belugas are pretty and friendly white whales, and their color helps them to stay alive and protects them from danger. There are many interesting facts about the Belugas that you should know and share with your kids.

Belugas are toothed whales, but they never chew their food. They swallow their prey. Another reason why the Beluga Whale is an endangered species is the fact that they have babies only once in three years. The female Beluga always gives birth to one calf and nurses it until it’s two years of age. The period between conception and birth for Beluga whales is 15 months. So, all in all, a female Beluga can give birth to only one new offspring every three-and-a-half years. The word Beluga comes from the Russian word for white. Although, they are born dark-grey, and it takes eight years for them to turn completely white. Amazing, right? Beluga whales can swim backwards. Beluga whales, just like dolphins, have been known to save people’s’ lives by pushing them to the surface when they are drowning. A captive Beluga saved a free diver’s life in 2009 while she was competing. This fact only confirms how good animals are to us even after all the cruelty they suffer. The Belugas are threatened mostly by being captured for captivity, hunting, climate change, oil and gas development, and industrial pollution. The wild predators that hunt them are Orcas and polar bears. Beluga whales are also known as the canaries of the ocean because of their incredible capability to produce different sounds. Scientists recorded eleven types of sounds that Belugas use to communicate with each other, to identify objects or calculate distance. They have a bulbous structure in their forehead that serves as an echo box where all the sounds come from. High-pitched whistles, clicks, mews, bleats, chirps, and bell-like tones are some of the sounds recognized by scientists. The Beluga’s neck is incredibly flexible and can move up and down and left and right. Such neck flexibility helps the whale to spot their prey easily. Beluga whales living in captivity have been recorded mimicking the human voice. It’s quite amazing to hear them imitating the human voice, but on the other hand, that means they spend so much time surrounded by people in an environment that is not their natural habitat. Beluga whales are highly social creatures that like to communicate with each other and with other species as well. They live in groups called pods, and they travel together everywhere. To spot them in real life, you must visit the Arctic Ocean coastal waters where they spend most of their time. Belugas can live 70 to 80 years, though in captivity they only reach a half of that age. Beluga whales can dive up to 25 minutes non-stop, and reach depths of 2624 feet. The beluga can change the shape of its bulbous forehead, called a “melon”, by blowing air around its sinuses.

Credit : Out door revival

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What are seamounts underwater?

Seamounts are underwater mountains rising over 1000 metres from the ocean floor. They do not reach the water's surface. They are formed by extinct volcanoes whose lava piles suddenly rise to form peaks. They are important manne ecosistems that support a wide variety of oceanic wildlife, from corals to sharks . Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Loihi in the Hawaiian Islands.

Because of their abundance, seamounts are one of the most common marine ecosystems in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton, corals, fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry, and many seamounts support extensive fisheries. There are ongoing concerns on the negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with the orange roughy (Hoplostethus atlanticus). 95% of ecological damage is done by bottom trawling, which scrapes whole ecosystems off seamounts.

Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis.

Credit : Wikipedia 

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After corals, fish losing their colour

An organism's appearance and body colour serve various purposes and they are strongly linked to the environment. In the marine environment, colouration is tied to how light penetrates ocean water and an animal's ability to blend in with its surroundings. A new study has found that fish communities on the Great Barrier Reef in Australia may become less colourful as corals bleach. The researchers studied the reef health, coral types, and resident fish over three decades.

The Great Barrier Reef, the largest coral reef system on Earth, has been subject to frequent bleaching events due to global warming in the past few decades. Coral bleaching events profoundly change the make-up of the ecosystem. Researchers say the loss of corals is a likely factor in the disappearance of brightly-coloured fish in the GBR.

The study looked at the diversity of colours found in communities of reef fishes and related that to the types of habitats where those fishes live.

 Fish communities in healthy parts of the reef with plentiful complex corals were compared to other areas where bleached corals dominate in the wake of major disturbances, such as heatwaves. The researchers found that as the cover of structurally complex corals increases on a reef, the range of colours present on fishes living and around them also increases. The diversity of fish colours declines in areas covered in dead, damaged corals. The bleached and dead corals probably provide less protection from predators for brightly-coloured fishes.

The researchers also found that the eye-catching yellow and green fishes, such as the lemon damselfish and green coral goby, have declined by about two-thirds, since the first recorded mass bleaching event of the reefs around Orpheus Island in 1998.

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I want to know about a career in oceanography and how to go about it.

Oceanography is a highly interesting area of study. Technically speaking, it is the scientific study of all aspects of the oceans, their boundaries and their continents. While the exact nature of work in this field varies with different specialized branches, oceanography, in general, is a research oriented profession. It is a multi-disciplinary science.

Oceanographers study the seas, its coastline, estuaries, coastal waters, shelves and the ocean bed. Their work combines the scientific knowledge of biology, chemistry, physics, geology, geophysics, mathematics and engineering science.

A career in oceanography is bound to provide both challenge and opportunity to those with an intrinsic curiosity about the world around them. It provides a true sense of excitement in the discovery of the vast realm of the unknown which exists within our oceans.

You will need to complete graduation (B.Sc.) in the pure sciences before going for M.Sc. in oceanography. Duration of the courses is three years. This field requires highly-skilled people, so a Ph.D. is essential. Most of the Indian educational institutions that provide oceanography courses are located in the states bordering the coast.

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