Theme: Marshes

 

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Text, Viewspace. The show will continue in 15 seconds. Coming up: View Earth's marshes from above with NASA satellites! 

 

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A satellite view of the planet from above showing blue-green wetlands between the land and sea masses. Text, Stinky, noxious, evil, and worthless are just a few of the words that have been used to describe marshes. An illustration of a beast with large bulging eyes, a wide grinning mouth of sharp teeth, webbed paws on long arms and spiky furry fins on its back. Text, During the Iron Age, the Celts believed spirits inhabited marshes. They appeased these phantoms by offering weapons, cauldrons, wagons, and perhaps even sacrificed humans to the marsh. A photo of a factory at the edge of a marsh and the land being stripped away. Text, Modern humans haven't been kind to marshes either. They've drained them to use the land for other purposes. Photos of geese and herons in the shallows. Text, But marsh lands are far from worthless. They are among the most vibrant ecosystems on the planet. 

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Text, Myth versus Reality. An ancient drawing of a ship at sea surrounded by monsters. A satellite photo of blue-green and brown wetlands. Myth, Marshes are smelly, poisonous wastelands with no economic value.

 

Reality, The economic value of marshes and other wetlands has been estimated to be many trillions of dollars. Marshes contribute to economies by providing rich habitat for plants and animals, supporting fisheries and recreational areas. Marshes slow and store flood waters, reducing damage to buildings and roads, and filter sediment and pollutants from water. Many cities are now building marshes to help manage and treat wastewater and rainwater runoff.

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

 

There are two types of marshes.

 

Italy and Florida.

 

Italy, Tidal. Florida, Non-Tidal

 

Tidal marshes are found along protected coastlines. They can be freshwater, salt water, or brackish (slightly salty) marshes, but all are influenced by the motion of ocean tides. Tidal marshes are important coastline buffers. They slow shoreline erosion and protect the coast from stormy seas. They also protect oceans by absorbing sediment and excess nutrients that rivers carry to the sea.

 

A red circle highlights a Tidal Marsh, Venetian Lagoon, Italy.

 

The Venetian Lagoon holds salt marshes and is the largest wetland in the Mediterranean basin.

 

Non-tidal marshes are the most common wetlands in North America. They hold mostly fresh water, but some are brackish.

 

A red circle near Lake Okeechobee highlights a Non-Tidal Marsh, Florida Peninsula. The Everglades in southern Florida are a vast array of wetlands, including many non-tidal marshes.

 

Water leaving Lake Okeechobee forms a vast, 60-mile-wide, slow-moving river that flows southward to Florida Bay.

 

Suspended sediment is carried to Florida's southern shoreline, making it appear turquoise in this image.

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Text, Farewell Spit. South Island of New Zealand. A satellite image of a long sickle-shaped strip of land curving away from the island. Text, On the northern tip of New Zealand's South Island, Farewell Spit stretches nearly 20 miles eastward into the Tasman Sea. A sandy beach lines the north side of the spit along the Tasman Sea, while an intricate wetland ecosystem faces south toward Golden Bay. A highlighted circle frames the spit.

 

Text, The tidal marshes on the spit's southern side are protected by mudflats, which are alternately exposed and inundated with the tidal rhythms of the ocean. A red circle appears around the mudflats on the south side of the curved spit, ribboned with rivers emptying into the bay. Text, the submerged tidal flats are etched with many channels and appear in shades of bluish purple. More than 80 species of wetland birds have been observed at Farewell Spit, and the tidal mudflats are a molting site for 12,000 black swans.

 
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Text, marshes Under Threat

 

5%. Roughly 5 percent of Earth's surface holds wetlands.

 

Mississippi River Delta, 2005 NASA Image. These areas, where land and water blend, are found at every latitude (from the tundra to the tropics) and on every continent except Antarctica. Marshes are wetlands saturated with standing water, ranging from less than an inch to several feet deep.

 

Soft-stemmed plants like cattails and grasses are typical marsh plants.

 

You can think of marshes as flooded grasslands.

 

An egret, geese, ducks and a beaver. Marshes hold and support more life than any other ecosystem of the same size.

 

Ganges Delta, Bangladesh, 2007 NASA Image. Marshes recharge groundwater supplies and moderate stream flow, which is an especially important function during droughts.

 

During floods, marshes help slow water through the watershed, minimizing flood damage.

 

Sediment and pollutants, like nitrogen and phosphorus from fertilizers, are filtered by marshes.

 

Vegetation and microorganisms in the marshes can use these pollutants, improving water quality.

 

The benefit of marshes and other types of wetlands weren't always appreciated, and many have been destroyed.

 

The United States had more than 300 million acres of freshwater wetlands in 1780.

 

Today there are less than 100 million acres.

 

Most of the lost wetlands were drained for agricultural use in the early 1900s.

 

One of the drained wetlands was Horicon Marsh in central Wisconsin.

 

Farmers tried to grow onions, carrots, and potatoes there, but the heavy peat soils retained spring moisture, making it hard to grow anything.

 

Trying to improve their crops, farmers plowed the marsh vegetation, exposing the underlined peat.

 

But once the peat dried, it caught fire easily.

 

By 1922, peat fires dominated the area. They raged for 12 years until, in 1934, the Rock River was dammed and water began to saturate the peat again.

 

Today, the marsh is still being restored.

 

A swirl of cyanobacteria on Guatemala's Lake Atitlan. Single-celled, aquatic organisms like blue-green algae or cyanobacteria can also threaten marshes.

 

Cyanobacteria are toxic to humans and other animals.

 

They grow quickly when nutrients like phosphorus and nitrogen, which are found in fertilizers, concentrate in the still water of the marsh.

 

These organisms can form large colonies, creating thick mats that block sunlight from reaching the water.

 

The bacteria also consume the oxygen in the water, creating dead zones where other plants and animals cannot survive.

 

Today we realize that marshes are cradles for life, vital ecosystems for migrating waterfowl and for humans.

 

Marshes and other wetlands are being restored around the world, but they are still under threat from pollutants, restricted water supply, and global climate change.

 
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Text, Mississippi River Delta, United States. The Mississippi River carbs its way through the heart of the North American continent before pouring into the Gulf of Mexico through the Louisiana wetlands.

 

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As the river enters the Gulf of Mexico, it loses energy and dumps its load of sediment.

 

Details of the delta. Text, This mud has accumulated over millions of years to build the delta.

 

Most of the land we see in this image consists of mud flats and marshlands.

 

The area holds little human settlement because the land is constantly changing.

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Text, Myth VS Reality.

 

Myth, All marsh fires are bad.

 

Reality. While deep peat fires are bad for marshes, some marsh fires are beneficial. Marsh fires can stimulate new growth of marsh grasses and destroy woody plants that shade and kill the grasses.

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Satellite image of a red-brown land.

 

Text, Lake Carnegie, Western Australia. Ephemeral Lake Carnegie in Western Australia holds water only during periods of significant rainfall. In dry years, it is a muddy marsh.

 

An area on the image is circled and enlarged. The red-brown land transitions to bright green and blue colors.

 

Text, Images like this are created when a satellite gathers reflected sunlight from Earth's surface. Data are then processed and turned into color-coded maps of the land.

 

In this false-color composite image, black indicates deep water, while light blue is shallower water mixed with sediment.

 

Areas with vegetation are green, while bare ground is varying shades of red to brown.

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An animated globe turns. Text, World of Change, Mesopotamian Marshes

 

A river valley. Text, Mesopotamian Marshes Iran and Iraq, World of Change., 2000-2010. Alongside the Tigris and Euphrates Rivers, the Mesopotamian marshes in southern Iraq and Iran were the largest wetlands in the Middle East.

 

Men, canoes and animals in and around a waterway. Text, In the 1990s, the marshes were drained significantly by dams and canals built by Saddam Hussein's regime.

 

Men paddle amid lush green grasses. Text, After Hussein's reign ended in 2003, Iraqis began destroying dikes and canals, and the marshes were reflooded.

 

The Tigris and Euphrates Rivers on a map. Text, 2000. NASA satellite images show the dramatic transformation in the mid-2000s as well as the effects of a drought in 2009.

 

Marshes appear as large dark areas, vegetation is green, and bare ground is brown.

 

Changes in marsh, vegetation and bare ground over the years. 2001, 2002, 2003,

 

2004

 

2005

 

2006

 

2007

 

2008

 

2009

 

2010