Theme: Coral Reefs

 

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Text, Viewspace. The show will continue in 15 seconds. Coming up: Learn how NASA studies Earth's coral reefs. 

 

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The text appears on a background of stars which move slowly towards and past us. 

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An animated globe turns on a dark background.

 

Near the Coral Sea, a red circle around the Great Barrier Reef, Queensland, Australia.

 

Coral reefs are among the oldest and most diverse ecosystems on Earth.

 

Many coral reefs are thousands of years old.

 

Pie charts. Text, Reefs occupy less than 1% of the entire ocean floor. Yet, reefs provide a home for 25% of all marine species.

 

A wide variety of fish swim among the coral.

 

Icons of human beings. In a photo, two men fish from a small wooden boat. Text, Half a billion people also depend on coral reefs for food, their livelihood (from fishing or tourism), a natural defense from storms, and in some cases, the land they live on.

 

Florida Keys, USA

 

Coral reefs are the largest living structures on Earth and the only ones visible from space.

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Satellite image, green archipelago in turquoise ocean.

 

Text, New Caledonia, South Pacific Ocean. The South Pacific archipelago of New Caledonia is surrounded by the third longest coral reef system in the world.

 

Its reefs take a variety of shapes and support an exceptional diversity of species, including threatened fish, turtles, and marine mammals.

 

New Caledonia's reefs host an even greater variety of fish and corals than the more expansive Great Barrier Reef.

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Text, Myth Versus Reality. On a chart, the left-hand side is labeled Myth and the right-hand side is labeled Reality. Above the Myth column, an illustration of sea monsters attacking a ship. Above the Reality column, a satellite image of a body of water. Text in the Myth column, Corals are fossilized plants.

 

Text in the Reality column, Corals are small animals related to jellyfish. Each coral animal is called a polyp, and thousands of polyps form a colony. Hard corals extract calcium from seawater and use it to create a hardened structure for protection and growth. These tiny skeletons accumulate over thousands of years to form coral reefs.

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An animation of Earth in a star-filled sky. Text, at-a-GLANCE, Coral Reefs

 

The globe turns.

 

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The Pacific Ocean. A red circle around Fanning Atoll, Line Islands, Kiribati.

 

In the midst of a vast ocean, ringed islands of coral, called atolls, enclose shallow lagoons.

 

Atolls act as natural markers, encircling the places where now submerged volcanic islands once stood.

 

Arrows point to a Barrier Reef, an Atoll and a Fringing Reef. Society Islands of French Polynesia.

 

An atoll begins forming on the submerged rock just off the shores of an island, creating a fringing reef that traces the island's outline.

 

As the volcano subsides and the island erodes, the lagoon widens, transforming the reef into a barrier reef.

 

With continued subsidence and erosion, the island eventually disappears under water, leaving a ring of coral reef known as an atoll.

 

The whole process can take millions of years.

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Atafu Atoll, Tokelau Islands, South Pacific Ocean. Only about 5 miles wide, Atafu Atoll is the smallest member of the Tokelau Islands group in the South Pacific.

 

The ring shaped atoll formed as coral reefs build up around a now-submerged volcano. Vegetation grows where exposed portions of the reef of weathered to form soil.

 

A small village inhabits one corner of the atoll.

 

A red circle around the corner at the lower left.

 

Submerged coral reefs lighten the water of the lagoon.

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Text, Coral Reefs at Risk

 

Coral reefs are the rainforests of the sea.

 

Nowhere on Earth is there a wider variety of marine life than around coral reefs.

 

A group of yellow and blue fish

 

A shark swims along the seafloor.

 

Small fish swim in and around coral.

 

Text, but recently, many corals have been dying.

 

An ailment known as "bleaching" is affecting reefs in tropical waters around the world.

 

Corals are small, tentacled marine animals that usually live in colonies.

 

Most corals are transparent and have no color of their own.

 

Instead, the corals get their color from symbiotic algae that live inside them.

 

These algae help many corals build hard, protective structures.

 

Over thousands of years, coral colonies build up these structures into large coral reefs that can often be seen from space.

 

Corals are acutely sensitive to changes in their environment.

 

Pollution

 

Storms

 

Disease

 

Destructive fishing practices

 

Ocean temperature change

 

These pressures can put corals under stress.

 

When corals are stressed, they often expel their algae.

 

Without algae, the transparent corals look pale or white, the color of their stony reef.

 

This is "coral bleaching."

 

Corals can use their tentacles to capture food, but reef-building corals usually get most of their energy from their symbiotic algae.

 

Without the algae, bleached corals often starve and die within a few weeks.

 

Corals that do survive are more susceptible to disease and other threats.

 

It can take decades for a reef to recover.

 

Typically, other sea creatures will abandon a dead or dying reef.

 

The ocean loses a once-thriving habitat, while people lose a source of food and income.

 

Increases in water temperature have caused most of the bleaching episodes in recent decades

 

Fortunately, some satellites are equipped to record and map the surface temperatures of the oceans.

 

These satellite maps help us identify where temperature changes could be causing corals to bleach and predict where reefs might be in danger of bleaching.

 

Satellites can also survey reefs in remote locations in a fraction of the time it takes from boats or airplanes.

 

In addition, they can observe reefs regularly to look for changes.

 

Marine scientists and volunteers are working to better understand the causes of coral bleaching to learn just how many reefs are dying and find ways to protect these natural treasures.

 

In these efforts, satellite observations are a valuable resource for monitoring and assessing the health of the "rainforests of the sea."

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Madagascar, Indian Ocean. Unusually high ocean temperatures in 1998 and 2000 took a toll on these reefs off the southwestern coast of Madagascar.

 

On some reefs, nearly 99 percent of corals died, and years later, they still showed no signs of recovery. Other bleached reefs, however, showed some potential for recovery.

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Text, Myth versus Reality. A table in which Myth is on the left and Reality is on the right. Text, Myth, Coral reefs exist only in warm climates and in shallow water.

 

Reality, While most coral reefs do form in warm, shallow seas, some corals thrive in cold climates and deep in the ocean. However, we know less about deep-sea and cold-water corals than we do about their tropical, shallow-water cousins, because they are harder to access and to study.

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Text, The Maldives, Indian Ocean. A chain of 1192 small coral islands stretches across roughly 550 miles of the Indian Ocean, composing the island nation known as the Maldives.

 

Fishing and tourism are the two major industries in the Maldives.

 

Satellite images have helped map the Maldives and prove that winds and waves shape these reefs and Islands.