The Sargasso Sea, located entirely within the Atlantic Ocean, is the only sea without a land boundary

The Sargasso Sea is a vast patch of ocean is named for a genus of free-floating seaweed called <abbr title="Both Sargassum and Sargasso are derived from a
Portuguese word for a variety of grape. The men traveling with Columbus thought the air bladders of the Sargassum weed looked like small grapes.">Sargassum. While there are many different
types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbors species of sargassum that are 'holopelagic' — this means that the algae not only freely floats
around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean.

Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for marine species,such as shrimp, crab, and fish, that have adapted specifically to this floating algae. The Sargasso Sea is a spawning site for threatened and endangered eels, as well as white marlin, porbeagle shark, and dolphinfish. Humpback whales annually migrate through the Sargasso Sea. Commercial fish, such as tuna, and birds also migrate through the Sargasso Sea and depend on it for food.

While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents. It lies within the Northern Atlantic Subtropical Gyre. The Gulf Stream establishes the Sargasso Sea's western boundary, while the Sea is further defined to the north by the North Atlantic Current, to the east by the Canary Current, and to the south by the North Atlantic Equatorial Current. Since this area is defined by boundary currents, it's borders are dynamic, correlating roughly with the Azores High Pressure Center for any particular season.

What's the difference between an ocean and a sea? (Ocean Fact)

Sargassum: A Complex 'Island' Community at Sea (NOAA's Ocean Explorer)

Sampling the Sargassum Community: Dip Nets and Green-Light Lures (NOAA's Ocean Explorer)

NOAA's Harmful Algal Bloom Operational Forecast System in the Gulf of Mexico identifies whether or not a bloom of algae is likely to contain a toxic species, where it is, how big it is, where it's headed, and if it could become more severe in the near future. Like a weather forecast, this system provides officials advance warning to test and close beaches and shellfish beds more precisely and for a shorter period of time.

This system relies on satellite imagery, field observations, models, public health reports, and buoy data to provide information on bloom events. Forecasters create a public HAB conditions report using this data and information to provide the likelihood of respiratory irritation impacts to people in the area over the next three to four days.

In addition to the conditions report, NOAA issues a HAB Bulletin for federal, state, and local coastal resource managers. The bulletin includes a summary of present bloom conditions and boundaries based on water samples and satellite imagery. It forecasts whether or not conditions are favorable for bloom formation, where the bloom may go, and whether algae concentrations are likely to intensify in the near future.

Expert oceanographers at NOAA analyse available data and models in order to create accurate bulletins. To ensure the highest degree of accuracy, all operational HAB forecasts undergo secondary review prior to dissemination.

The Harmful Algal Bloom Operational Forecast System depends on the dedication, energy, and feedback from individuals at partner agencies and other organizations working on this issue. Blooms of harmful algae are not unique to the Gulf of Mexico, so NOAA continues to work with local agencies in Maine, Massachusetts, Ohio, Washington, Oregon, California and elsewhere in the U.S. to make new forecasts operational over the next five years.

NOAA Harmful Algal Bloom Operational Forecast System

Explore: Harmful Algal Blooms

Diving Deeper podcast (10.7.09) - Harmful Algal Blooms

Center for Operational Oceanographic Products and Services

National Centers for Coastal Ocean Science

You won't find Spirobranchus giganteus, also known as the Christmas tree worm, eating your fir tree this year. The common name for these worms is derived from their appearance, not their habitat or diet.

Each worm has two brightly colored crowns that protrude from its tube-like body. These Christmas tree-like crowns are composed of radioles, or hair-like appendages radiating from the worm's central spine. These appendages are used for respiration and to catch dinner, which typically consists of microscopic plants, or phytoplankton, floating in the water.

These worms are sedentary, meaning that once they find a place they like, they don’t move much. In fact, while the colorful crowns of these worms are visible, most of their bodies are anchored in burrows that they bore into live coral. When startled, Christmas tree worms rapidly retract into their burrows, hiding from would-be predators.

Christmas tree worms come in a variety of bright colors. They aren’t very big, averaging about 1.5 inches in length. However, because of their distinctive shape, beauty, and color, these worms are easily spotted. They are some of the most widely recognized polycheates, or marine burrowing, segmented worms out there.

Florida Keys National Marine Sanctuary: Christmas Tree Worms

Flower Garden Banks National Marine Sanctuary: Christmas Tree Worms

Encyclopedia of the Sanctuaries: Christmas Tree Worms

Corals have long been popular as souvenirs, for home decor, and in jewelry, but many consumers are unaware that these beautiful structures are made by living creatures. Fewer still realize that corals are dying off at alarming rates around the world.
Coral reefs are some of the most biologically rich and economically valuable ecosystems on Earth, but they are increasingly threatened by pollution, invasive species, fishing, disease, bleaching, and global climate change.

Strong consumer demand for coral, heightened over the holiday season, is another factor that is contributing to the decline of coral reefs.

Corals are popular as souvenirs, for home decor and in costume jewelry, yet corals are living animals that eat, grow and reproduce. It takes corals decades or longer to create reef structures, so leave corals and other marine life on the reef.

NOAA Coral Reef Watch

NOAA Coral Reef Conservation Program

NOAA Coral Reef Information System

10 Things You Need to Know About Marine Debris

Scientists are relying on computer models to predict the path of the debris, but models can only assume general direction and timing. Since winds and ocean currents constantly change, it is very difficult to predict an exact date and location for the arrival of any debris on U.S. coasts without more information.

Models run by NOAA researchers and other scientists show some debris could pass near, or wash ashore, in the Northwestern Hawaiian Islands as early as this winter, approach the West Coast of the United States and Canada in 2013, and then circle back to the main Hawaiian Islands in 2014.

NOAA is leading efforts within the federal government -- along with the U.S. Environmental Protection Agency (EPA) and other federal agencies, as well as non-governmental organizations and academia -- to understand the nature and amount of items that may wash ashore. NOAA is also working to understand the many possible impact scenarios and how to best protect our natural resources and coasts. It is considered highly unlikely that the tsunami-generated marine debris is contaminated with radioactive material because the debris washed out to sea before the release of radioactive water from the power plant. The EPA and the U.S. Food and Drug Administration are monitoring for radioactivity.

Frequently Asked Questions: Debris from Japan Tsunami

NOAA Marine Debris Program

Marine Debris (Diving Deeper podcast, 2.23.09)

10 Things You Need to Know About Marine Debris

The cryosphere is the frozen water part of the Earth system

There are places on Earth that are so cold that water is frozen solid. These areas of snow or ice, which are subject to temperatures below 0°C for at least part of the year, compose the cryosphere. The term “cryosphere” comes from the Greek word, “krios,” which means cold.

Ice and snow on land are one part of the cryosphere. This includes the largest parts of the cryosphere, the continental ice sheets found in Greenland and Antarctica, as well as ice caps, glaciers, and areas of snow and permafrost. When continental ice flows out from land and to the sea surface, we get shelf ice.

The other part of the cryosphere is ice that is found in water. This includes frozen parts of the ocean, such as waters surrounding Antarctica and the Arctic. It also includes frozen rivers and lakes, which mainly occur in polar areas.

The components of the cryosphere play an important role in the Earth’s climate. Snow and ice reflect heat from the sun, helping to regulate our planet’s temperature. Because polar regions are some of the most sensitive to climate shifts, the cryosphere may be one of the first places where scientists are able to identify global changes in climate.

For more information:
Why is the ocean salty?
U.S. National Ice Center
What is an iceberg?
NOAA's Arctic Theme Page

Tide and current data is available from NOAA's Center for Operational Products and Services website

Tides

Tide Predictions. Generate a graphical display or a tabular listing of daily high and low tide predictions for more than 3,000 locations around the nation. Predictions may be generated up to two years in advance.

Real-Time Tide Data. Access current water levels from over 3,000 tidal stations. For the Great Lakes region, see Great Lakes Real-Time Water Level Data.

Historic Tide Data. For a given NOAA tide station, retrieve historic tide data from the earliest to the most recent dates for which data is available. For the Great Lakes region, see Great Lakes Historic Water Level Data.

Sea Levels. View a global map depicting regional trends in sea level, with arrows representing the direction and magnitude of change.

Tides Online. Choose a tide station by state and location to view current tidal information, wind speeds, air pressure, and air temperature. For the Great Lakes region, visit Great Lakes Online.

Tsunami-Capable Tide Stations. Access high resolution, one-minute water level sample data used to support national tsunami warning and mitigation efforts.

Tide Station Index. Generate a per-state list of all NOAA tide stations, including station number, name, location, installation date, and more.

Tidal Datums. Access NOAA's tidal datums. Scientists use datums to define "normal" water levels as a starting point from which all measurements are made. The numbers that appear on a nautical chart represent water depths measured relative to such a datum.

Currents

Real-Time Current Data. View real-time current data collected by NOAA current meters around the nation.

Historic Current Data. View historic current data collected by active and retired NOAA current meters around the nation.

Tidal Current Predictions. Obtain tidal current predictions for more than 2700 tidal current stations nationwide.

Other CO-OPS Products and Services

PORTS®. NOAA's Physical Oceanographic Real-Time System (PORTS®) improves the safety and efficiency of maritime commerce and coastal resource management through the integration of real-time environmental observations, forecasts and other geospatial information. PORTS® measures and disseminates observations and predictions of water levels, currents, salinity, and meteorological parameters (e.g., winds, atmospheric pressure, air and water temperatures) that mariners need to navigate safely in and around key maritime ports around the nation.

NowCOAST. NowCOAST is a web mapping portal that provides spatially referenced links to thousands of real-time coastal observations and NOAA forecasts of interest to the marine community.

Storm QuickLook. Access near real-time oceanographic and meteorological observations at locations affected by a tropical cyclone.

Operational Forecast System. This service offers nowcasts and short-term forecasts for select regions (critical ports, harbors, estuaries, Great Lakes, and coastal waters). These real-time observations and forecasts deliver present and future states of water levels, along with currents and other relevant oceanographic variables, such as salinity and temperature.

'Turkeyfish' is another name for lionfish.

Viewed from the right angle, the ornate fins of the lionfish resemble turkey plumage. That's why 'turkeyfish' is one of the many imaginative names people use when referring to the lionfish.

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 Mexico.

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.

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 threat to, Atlantic Ocean ecosystems.

For more information:
Learn more about invasive lionfish from NOAA's Center for Coastal Fisheries and Habitat Research

While we often think of the earth as a sphere, our planet is actually very bumpy and irregular.

The radius at the equator is larger than at the poles due to the long-term effects of the earth's rotation.  And, at a smaller scale, there is topography—mountains have more mass than a valley and thus the pull of gravity is regionally stronger near mountains.

All of these large and small variations to the size, shape, and mass distribution of the earth cause slight variations in the acceleration of gravity (or the "strength" of gravity's pull). These variations determine the shape of the planet's liquid environment.

If one were to remove the tides and currents from the ocean, it would settle onto a smoothly undulating shape (rising where gravity is high, sinking where gravity is low).

This irregular shape is called "the geoid," a surface which defines zero elevation. Using complex math and gravity readings on land, surveyors extend this
imaginary line through the continents. This model
is used to measure surface elevations with a high
degree of accuracy.

For more information:
National Geodetic Survey
National Spatial Reference System
NGS Geoid information
Diving Deeper Podcast, What is geodesy?

NOAA's Digital Coast provides the data, tools, and training that communities use to manage their coastal resources

Geospatial data alone is not enough. For data to be truly useful, additional training, tools, and information are often required. The Digital Coast provides this complete package in one place for coastal officials.

The Digital Coast is a cost-effective resource for coastal communities. Through the Digital Coast, users can find the information they need to explore the implications of sea level rise, conduct risk and vulnerability assessments, develop community green infrastructure plans, and much more. The site also provides valuable case studies to highlight how data and tools available from the Digital Coast have been used to address coastal management issues.

The Digital Coast's success is driven in large part by content contributions from many trusted sources, including federal, state, and local government agencies, non-profit organizations, and the private sector. A strong partnership group also helps to validate the information provided through the Digital Coast, ensuring that it is helpful and relevant to coastal managers. These partner organizations have found that the Digital Coast provides a way to work together on initiatives that not only benefit their organizations, but can also have a big impact on efforts to protect coastal resources and communities.

For more information:

Digital Coast

NOAA Coastal Services Center