remiconnesson/oceanservice-noaa-facts huggingface dataset:
# What is a kelp forest?

## Kelp forests provide food and shelter for thousands of species

![kelp forest](kelp-forest.jpg "Kelp forests provide food and shelter for thousands of species")

In ideal conditions, kelp can grow up to 18 inches per day, and in stark contrast to the colorful and slow-growing corals, the giant kelp canopies tower above the ocean floor. Like trees in a forest, these giant algae provide food and shelter for many organisms. Also like a terrestrial forest, kelp forests experience seasonal changes. Storms and large weather events, like [El Niño](ninonina.html), can tear and dislodge the kelp, leaving a tattered winter forest to begin its growth again each spring.

Kelp forests can be seen along much of the west coast of North America. Kelp are large brown algae that live in cool, relatively shallow waters close to the shore. They grow in dense groupings much like a forest on land. These underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

Kelp forests harbor a greater variety and higher diversity of plants and animals than almost any other ocean community. Many organisms use the thick blades as a safe shelter for their young from predators or even rough storms.

Among the many mammals and birds that use kelp forests for protection or feeding are seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons, cormorants, and shore birds.

These dense canopies of algae generally occur in cold, nutrient-rich waters. Because of their dependency upon light for photosynthesis, kelp forests form in shallow open waters and are rarely found deeper than 49-131 feet.

NOAA scientists study kelp forests by visiting the same locations over and over to assess the presence and abundance of a variety of organisms. Monitoring allows marine scientists to determine if the kelp forest is changing over time and to identify the cause of those changes, whether natural or human.

Did you know? - 

- The [Elkhorn Slough National Estuarine Research Reserve](https://coast.noaa.gov/nerrs/reserves/elkhorn-slough.html) in California is home to a population of more than 100 sea otters. See for yourself! Visit Elkhorn Slough's real-time [Otter Cam](http://www.elkhornslough.org/ottercam/).
# What is a coral reef made of?

## A coral reef is made of thin layers of calcium carbonate

![Coral polyps form a living mat over a calcium carbonate skeleton.](coral-madeof.jpg "A coral reef is made of thin layers of calcium carbonate")

Coral polyps form a living mat over a calcium carbonate skeleton.

Stony corals (or scleractinians) are the corals primarily responsible for laying the foundations of, and building up, reef structures. Massive reef structures are formed when each individual stony coral organism—or polyp—secretes a skeleton of calcium carbonate.

Most stony corals have very small polyps, averaging one to three millimeters (0.04 to 0.12 inches) in diameter, but entire colonies can grow very large and weigh several tons. These colonies consist of millions of polyps that grow on top of the limestone remains of former colonies, eventually forming massive reefs.

In general, massive corals tend to grow slowly, increasing in size from 0.5 to two centimeters (0.2 to 0.8 inches) per year. However, under favorable conditions (lots of light, consistent temperature, moderate wave action), some species can grow as much as 4.5 centimeters (1.8 inches) per year.
# What is a mangrove forest?

![A Floridian Mangrove forest](/facts/mangrove-forest.jpg "Mangrove forest in Loxahatchee, Florida.")

Mangrove forest in Loxahatchee, Florida.

There are about 80 different species of mangrove trees. All of these trees grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate. Mangrove forests only grow at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures.

Many mangrove forests can be recognized by their dense tangle of prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides, which means that most mangroves get flooded at least twice per day. The roots also slow the movement of tidal waters, causing sediments to settle out of the water and build up the muddy bottom.

Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fish and other organisms seeking food and shelter from predators.
# Can the ocean freeze?

## Ocean water freezes at a lower temperature than freshwater.

![The Arctic](/facts/arctic.jpg "The Arctic")

At least 15 percent of the ocean is covered by sea ice some part of the year.

Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 32 degrees Fahrenheit but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it. When seawater freezes, however, the ice contains very little salt because only the water part freezes. It can be melted down to use as drinking water.

At least 15 percent of the ocean is covered by sea ice some part of the year. On average, sea ice covers almost about 10 million square miles of the Earth.

Sea water becomes more and more dense as it becomes colder, right down to its freezing point. Fresh water, on the other hand, is most dense while still at 39.2 degrees Fahrenheit, well above the freezing point. The average temperature of all ocean water is about 38.3 degrees Fahrenheit.
# What's the difference between an ocean and a sea?

## In terms of geography, seas are **smaller** than oceans and are usually located where the **land and ocean meet**. Typically, seas are **partially enclosed by land**.

![description of image](oceanorsea.jpg "short caption")

Seas are found on the margins of the ocean and are partially enclosed by land. Here, you can see that the Bering Sea is part of the Pacific Ocean.

Many people use the terms "ocean" and "sea" interchangeably when speaking about the ocean, but there is a difference between the two terms when speaking of geography (the study of the Earth's surface).

Seas are smaller than oceans and are usually located where the land and ocean meet. Typically, seas are partially enclosed by land.

The [Sargasso Sea](/facts/sargassosea.html) is an exception. It is defined only by ocean currents.
# Is change important to estuaries?

## Changing conditions are a **necessary part of healthy, functioning** estuaries

![description of image](estuary-change.jpg "short caption")

Estuaries experience change many times a day due to tides. Shown here: Located at the northern end of the Ten Thousand Islands on the gulf coast of Florida, the Rookery Bay National Estuarine Research Reserve represents one of the few remaining undisturbed mangrove estuaries in North America.  

[Estuaries](/facts/estuary.html) are tidally driven. Tides flush the system and provide nutrients to keep food webs functional. By doing this, tides create constantly changing conditions of exposure to air or increased levels of water in an estuarine environment. Because of tides, the water levels in an estuary are going up and down several times a day.

Estuarine organisms can adapt quite well to these changing conditions in estuaries. For example, fish or crabs are mobile and can move as needed throughout the day to adjust to changes in the estuary.

In addition, weather patterns, seasonal cycles, and climate change also affect and can change conditions in estuaries.

Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are home to unique plant and animal communities that have adapted to brackish water.
# What are the Seven Seas?

![Image of the ocean](/facts/sea.jpg)

_The exact origin of the phrase 'Seven Seas' is uncertain, although there are references in ancient literature that date back thousands of years._

The origins of the phrase 'Seven Seas' can be traced to ancient times.

In various cultures at different times in history, the Seven Seas has referred to bodies of water along trade routes, regional bodies of water, or exotic and far-away bodies of water.

In Greek literature (which is where the phrase entered Western literature), the Seven Seas were the Aegean, Adriatic, Mediterranean, Black, Red, and Caspian seas, with the Persian Gulf thrown in as a "sea."

In Medieval European literature, the phrase referred to the North Sea, Baltic, Atlantic, Mediterranean, Black, Red, and Arabian seas.

As trade picked up across the Atlantic, the concept of the Seven Seas changed again. Mariners then referred to the Seven Seas as the Arctic, the Atlantic, the Indian, the Pacific, the Mediterranean, the Caribbean, and the Gulf of America.

Not many people use this phrase today, but you could say that the modern Seven Seas include the Arctic, North Atlantic, South Atlantic, North Pacific, South Pacific, Indian, and Southern Oceans.

However, our ocean is more commonly geographically divided into the Atlantic, Pacific, Indian, Arctic, and Southern (Antarctic).
# How does oil impact marine life?

![oiled shellfish, birds, and turtle](/facts/kemp-turtle960.jpg)

_Following an oil spill, there are specialists and veterinarians to deal with oiled wildlife. These experts are trained on how to clean oil from animals, rehabilitate them, and return them to the environment._

Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water repellency of a bird's feathers, thus exposing these creatures to the harsh elements. Without the ability to repel water and insulate from the cold water, birds and mammals will die from hypothermia.

Juvenile sea turtles can also become trapped in oil and mistake it for food. Dolphins and whales can inhale oil, which can affect lungs, immune function and reproduction. Many birds and animals also ingest oil when they try to clean themselves, which can poison them.

Fish, shellfish, and corals may not be exposed immediately, but can come into contact with oil if it is mixed into the water column — shellfish can also be exposed in the intertidal zone. When exposed to oil, adult fish may experience reduced growth, enlarged livers, changes in heart and respiration rates, fin erosion, and reproduction impairment. Fish eggs and larvae can be especially sensitive to lethal and sublethal impacts. Even when lethal impacts are not observed, oil can make fish and shellfish unsafe for humans to eat.
# What is the EEZ?

## The **exclusive economic zone** is the zone where the U.S. and other coastal nations have jurisdiction over natural resources

![map of U.S. EEZ](eez.jpg "map of U.S. EEZ")

This NOAA map shows the U.S. exclusive economic zone.

The U.S. Exclusive Economic Zone (EEZ) extends no more than 200 nautical miles from the territorial sea baseline and is adjacent to the 12 nautical mile territorial sea of the U.S., including the Commonwealth of Puerto Rico, Guam, American Samoa, the U.S. Virgin Islands, the Commonwealth of the Northern Mariana Islands, and any other territory or possession over which the United States exercises sovereignty. 

Within the EEZ, the U.S. has:

-   Sovereign rights for the purpose of exploring, exploiting, conserving and managing natural resources, whether living and nonliving, of the seabed and subsoil and the superjacent waters and with regard to other activities for the economic exploitation and exploration of the zone, such as the production of energy from the water, currents and winds;
-   Jurisdiction as provided for in international and domestic laws with regard to the establishment and use of artificial islands, installations, and structures, marine scientific research, and the protection and preservation of the marine environment; and
-   Other rights and duties provided for under international and domestic laws.

_Note_:  Under certain U.S. fisheries laws, such as the [Magnuson-Stevens Fishery Conservation and Management Act](https://www.fisheries.noaa.gov/resource/document/magnuson-stevens-fishery-conservation-and-management-act), the term "exclusive economic zone" is defined as having an inner boundary that is coterminous with the seaward (or outer) boundary of each of the coastal states. While its _outer_ limit is the same as the EEZ on NOAA charts, its _inner_ limit is coterminous with the coastal states' boundary at 3 nautical miles, except for Texas, western Florida, and Puerto Rico, which claim a 9 nautical mile belt.
# What types of plants and animals live in an estuary?

![Great Blue Heron eating a fish in an estuary. (NOAA News)](/facts/estuaries_bird.jpg)

_Great Blue Heron eating a fish in an estuary. (NOAA News)_

Estuaries — areas where fresh and saltwater mix — are made up of many different types of habitats. These habitats can include oyster reefs, coral reefs, rocky shores, submerged aquatic vegetation, marshes, and mangroves. There are also different animals that live in each of these different habitats. Fish, shellfish, and migratory birds are just a few of the animals that can live in an estuary.

The Chesapeake Bay, as one example, includes several different habitats. There are oyster reefs where oysters, mud crabs, and small fish may be found. Also in the Bay, there is submerged aquatic vegetation where seahorses, blue crabs, and other fish live. Finally, there is open water where sea turtles or rays can be found.
# Why are lionfish a threat to Atlantic Ocean fish?

![Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats](/facts/lionfish-noaa-960.jpg "The invasive lionfish threaten native fish and the environment in U.S. Atlantic coastal waters")

_Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats._

Lionfish are native to the Indo-Pacific, but are now established along the southeast coast of the U.S., the Caribbean, and in parts of the Gulf of America.

How did the fish get to the Atlantic? While the exact cause is unknown, it's likely that humans provided a helping hand. Experts speculate that people have been dumping unwanted lionfish from home aquariums into the Atlantic Ocean for more than 25 years.

Since lionfish are not native to Atlantic waters, they have very few predators. They are carnivores that feed on small crustaceans and fish, including the young of important commercial fish species such as snapper and grouper.

Unfortunately, NOAA researchers have concluded that invasive lionfish populations will continue to grow and cannot be eliminated using conventional methods. Marine invaders are nearly impossible to eradicate once established.

How lionfish will affect native fish populations and commercial fishing industries has yet to be determined. What is known is that non-native species can dramatically affect native ecosystems and local fishing economies. Experts are carefully studying these invaders to better understand their role in, and potential threat to, Atlantic Ocean ecosystems.

Lionfish have venomous spines that can be very painful. Scientists are also actively studying these fish to better understand the potential threat that lionfish pose to key reef and commercial fish species. Learning more about the habits and preferences of lionfish in non-native waters also helps experts determine where to look for these invasive fish.
# What is an iceberg?

## An iceberg is ice that broke off from glaciers or shelf ice and is floating in open water.

![Iceberg located in Ross Sea, Antarctica.](/facts/iceberg.jpg "Iceberg located in Ross Sea, Antarctica.")

Iceberg located in Ross Sea, Antarctica.

To be classified as an iceberg, the height of the ice must be greater than 16 feet above sea level and the thickness must be 98-164 feet and the ice must cover an area of at least 5,382 square feet.

There are smaller pieces of ice known as “bergy bits” and “growlers.” Bergy bits and growlers can originate from glaciers or shelf ice, and may also be the result of a large iceberg that has broken up. A bergy bit is a medium to large fragment of ice. Its height is generally greater than three feet but less than 16 feet above sea level and its area is normally about 1,076-3,229 square feet. Growlers are smaller fragments of ice and are roughly the size of a truck or grand piano. They extend less than three feet above the sea surface and occupy an area of about 215 square feet.

Icebergs are also classified by shape, most commonly being either tabular or non-tabular. Tabular icebergs have steep sides and a flat top. Non-tabular icebergs have different shapes, with domes and spires.

Icebergs are monitored worldwide by the U.S. National Ice Center (NIC). NIC produces analyses and forecasts of Arctic, Antarctic, Great Lakes, and Chesapeake Bay ice conditions. NIC is the only organization that names and tracks all Antarctic Icebergs.
# Do volcanoes occur in the ocean?

## The greatest number of the Earth's volcanoes occur on the ocean floor.

![magma explosions and lava flows on West Mata volcano](/facts/volcano.jpg "magma explosions and lava flows on West Mata volcano")

ROV _Jason_ gets a close view of magma explosions and lava flows on West Mata volcano.

Volcanic eruptions occur only in certain places and do not occur randomly. This is because the Earth’s crust is broken into a series of slabs known as tectonic plates. These plates are rigid, but they “float” on a hotter, softer layer in the Earth's interior. As the plates move, they spread apart, collide, or slide past each other.

Sixty percent of all active volcanoes occur at the boundaries between tectonic plates. Most volcanoes are found along a belt, called the “Ring of Fire” that encircles the Pacific Ocean. Some volcanoes, like those that form the Hawaiian Islands, occur in the interior of plates at areas called “hot spots.”

Although most of the active volcanoes we see on land occur where plates collide, the greatest number of the Earth's volcanoes are hidden from view, occurring on the ocean floor along spreading ridges.
# What is marine snow?

 [](/facts/marine-snow.mp4) 

VIDEO: Biological debris that falls from higher in the water column is also known as marine snow. Some flakes fall for weeks before finally reaching the ocean floor.

As plants and animals near the surface of the ocean die and decay, they fall toward the seafloor, just like leaves and decaying material fall onto a forest floor. In addition to dead animals and plants, marine snow also includes fecal matter, sand, soot, and other inorganic dust.

The decaying material is referred to as “marine snow” because it looks a little bit like white fluffy bits. The “snowflakes” grow as they fall, some reaching several centimeters in diameter. Some flakes fall for weeks before finally reaching the ocean floor.

This continuous rain of marine snow provides food for many deep-sea creatures. Many animals in the dark parts of the ocean filter marine snow from the water or scavenge it from the seabed. NOAA scientists and others have measured the amount of useable material in marine snow and found that there is plenty of carbon and nitrogen to feed many of the scavengers in the deep sea.

The small percentage of material not consumed in shallower waters becomes incorporated into the muddy “ooze” blanketing the ocean floor, where it is further decomposed through biological activity. About three-quarters of the deep ocean floor is covered in this thick, smooth ooze. The ooze collects as much as [six meters](#) every million years.
# What is marine debris?

![NOAA divers release seal from marine debris entanglement.](/facts/seal-entanglement-960.jpg "NOAA divers release seal from marine debris entanglement.")

_NOAA divers release seal from marine debris entanglement. Entanglement in derelict fishing gear can lead to injury or death in marine organisms._

Marine debris injures and kills marine life, interferes with navigation safety, and poses a threat to human health. Our ocean and waterways are polluted with a wide variety of marine debris ranging from soda cans and plastic bags to derelict fishing gear and abandoned vessels. 

Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes.

Today, there is no place on Earth immune to this problem. A majority of the trash and debris that covers our beaches comes from storm drains and sewers, as well as from shoreline and recreational activities such as picnicking and beachgoing. Abandoned or discarded fishing gear is also a major problem because this trash can entangle, injure, maim, and drown marine wildlife and damage property.
# What are tides?

## Tides are caused by **gravitational pull** of the moon and the sun.

![The  NOAA San Francisco Tide Station, in operation for more than 150 years.](tides.jpg "The NOAA San Francisco Tide Station, in operation for more than 150 years.")

The rise and fall of the tides play an important role in the natural world and can have a marked effect on maritime-related activities. The image aboves shows the NOAA San Francisco Tide Station, in operation for more than 150 years.

Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores.

Tides are very long-period waves that move through the ocean in response to the forces exerted by the moon and sun. Tides originate in the ocean and progress toward the coastlines where they appear as the regular rise and fall of the sea surface.

When the highest part, or crest, of the wave reaches a particular location, high tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high tide and the low tide is called the tidal range.
# Why do we have an ocean?

## The ocean formed billions of years ago.

![The ocean formed billions of years ago.](/facts/why_oceans.jpg "The ocean formed billions of years ago.")

Over vast periods of time, our primitive ocean formed. Water remained a gas until the Earth cooled below 212 degrees Fahrenheit. At this time, about 3.8 billion years ago, the water condensed into rain which filled the basins that we now know as our world ocean.

Most scientists agree that the atmosphere and the ocean accumulated gradually over millions and millions of years with the continual 'degassing' of the Earth's interior.

According to this theory, the ocean formed from the escape of water vapor and other gases from the molten rocks of the Earth to the atmosphere surrounding the cooling planet.

After the Earth's surface had cooled to a temperature below the boiling point of water, rain began to fall—and continued to fall for centuries. As the water drained into the great hollows in the Earth's surface, the primeval ocean came into existence. The forces of gravity prevented the water from leaving the planet.