Corals belong to the animal kingdom, and are members of the same group of animals as jellyfish and sea anemones (Phylum: Cnidaria). The actual coral animal or 'polyp' is soft bodied, with tentacles like a sea anemone. The main difference is that corals secrete an external calcium carbonate skeleton and sea anemones do not. This hard skeleton forms the framework of coral reefs. The tiny coral polyps occupy little cups or corallites in the massive skeleton. Corals can be colonial or solitary and there are several hundred species, some are large and branching and grow rapidly at a rate of up to 10cm per year, while others are mound shaped, growing slowly at only 1cm per year.

In addition to the hard corals, there are a variety of soft corals like the common sea fan (Gorgonia ventalina). The calcium carbonate skeleton of soft corals is located within their bodies, allowing them to move with the wave action. Sea fans typically grow so that the wave action is moving over the broad plane of their bodies, so all of the sea fans in an area will be oriented in the same direction.

Reef building corals live in symbiotic association with zooxanthellae, single celled algae, which live in the tissue of the corals. The zooxanthellae produce the oxygen, that the corals need to survive, by photosynthesis; in return the algae are protected from grazing species and can access the nutrients that the coral excretes - a mutually beneficial association.

EXPLORE CORAL REEFS WITH ELENA 3 SNORKELING TOURS

Corals feed on zooplankton with the use of their tentacles. During daylight they mostly remain within their protective skeleton to avoid predation, but at night the tentacles are extended to allow them to feed.

Coral colonies grow by having the polyps bud off new polyps asexually. New colonies are established by the fragmentation of skeletal pieces or through the settling of planktonic coral lava on a hard substrate. The lava are the result of sexual reproduction.

What do corals need to grow? There are six major factors that limit coral reef development; water temperature and salinity, depth, light, sedimentation and emergence into air.

•  Coral reefs are only found between about 30 degrees north and south of the equator, where the water temperature is at least 70 degrees F, and optimal reef development occurs in waters where the mean annual temperatures are around 75 degrees F.

• Corals are intolerant of salinities that deviate significantly from that of seawater and gaps will occur in reefs where, for example, freshwater from a river enters the sea.

• Depth is also critical, coral reefs will not develop in water that is deeper than about 50-70m, and they grow most energetically at depths of 25m or less. Light, which is related to depth of water, is necessary for the zooxanthellae to photosynthesize. Without light the photosynthetic rate is reduced and with it the corals ability to secrete calcium carbonate.

• Corals also require clear water - sediment clogs their feeding structures and smothers them. For this reason corals usually grow most actively in areas of strong wave action, such as the windward side of a reef, where sediment is prevented from settling on the colonies.

• Finally corals reefs are limited in an upward direction by emergence into air. Most corals are killed by long exposure to air and so their upward growth is limited to the level of the lowest tides.

Troubled Oceans

The following link is full of information about Coral Reefs.

EXPLORE CORAL REEFS WITH ELENA 3 SNORKELING TOURS

Global Coral Reef Monitoring Network

Corals are damaged by uncontrolled tropical deforestation, coastal development, and discharge of wastes. As human populations grow, coral reefs and their surrounding waters are threatened by poor land-use practices and excessive inflow of nutrients.

Demand for seafood is so great in the Caribbean that many reefs are severely over fished, throwing off the delicate balance essential to the survival of the reef ecosystem. Too many nutrients and not enough plant-eating fish cause algae to overgrow and smother corals.

How can we help our coral reefs?

• Plant vegetation barriers along rivers and shorelines to reduce runoff.

• Force government agencies to establish moorings for boats to pick up and tie to, instead of damaging corals with their anchors.

• Pick up trash along beaches and in other coastal areas.

• Refrain from buying souvenirs, jewelry, or ornaments made of coral.

• Snorkel, dive, and anchor with care so as not to crush reef organisms.

• Buy only captive-bred aquarium fish

• Request seafood that have been sustainable harvested. Eat less seafood.

• Support education and research on coral reefs as well as reef-friendly legislation.

Caribbean coral reefs cover 80% less territory
July 18, 2003

BY PETER N. SPOTTS

For decades, marine scientists have tracked the loss of once-bountiful coral reefs in the Caribbean Sea. But few have tried to fit the disparate pieces of the coral reef puzzle into a regionwide picture.
Now a team of scientists is publishing what may be the first long-term look at changes in the Caribbean's corals. They find that hard corals--the backbone of reef systems--cover 80 percent less undersea terrain than they did 30 years ago.

Researchers say the Losses of Coral Reefs -- the marine equivalent of tropical rainforests in terms of biodiversity -- affect the region in several ways. They remove havens for maturing fish and other marine organisms, and destroy buffers that can protect shoreline from the full brunt of storm tides.

But the numbers also impart a ray of hope. They suggest that pollution, overfishing, and tourism are the primary causes of the decline. These local conditions are easier to handle than trying to offset the threats of long-term climate change, notes Dr. Isabelle Cote, a marine ecologist at the Tyndall Center for Climate Change Research in Britain and one of the study's researchers.

"There have been relatively few studies that have tried to pull this much information together over such a long time period for such a relatively large part of the planet," Roger Griffis, a reef expert at the National Oceanic and Atmospheric Administration, said. The results, published today in the journal Science, actually represent a spin-off of efforts to answer a different question. The team was trying to quantify the impact of hurricanes on reefs in the Caribbean.

Researchers examined 65 studies, conducted from 1977 to 1991, involving 263 sites in the region. They initially looked at what happened to the reefs when they were struck by hurricanes. "But to really understand whether hurricanes were leading to declines in coral, we needed a background picture," says Cote. Only then did the magnitude of the coral-loss problem emerge, stunning the team. Over the years, "people had a feeling that things were going badly," she says. "We've actually put a number on it. And it's much bigger than anyone expected."

After examining the numbers, the team concluded that climate change had less to do with the disappearing coral, than had human-generated problems, such as over-fishing. Cote explains that fledgling colonies of hard coral compete with kelp and other forms of "macro-algae" for sea-floor space. Overfishing has depleted herbivorous species that kept the macro-algae in check.

Disease has ravaged populations of sea-urchins, which also ate the macro-algae. Also, poor land-use practices have flushed more silt into rivers that empty into reefs.

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Report: Caribbean coral reefs down 80 percent
By Marsha Walton
CNN

--A new study paints a grim picture of the health of coral reefs across the Caribbean. In the past three decades, the amount of coral cover has dropped about 80 percent, according to researchers in the journal Science. A team of U.K. scientists compiled data from 263 separate reef sites in the Caribbean for this week's report, which they called the most extensive coral study ever of the region.

Some of the causes are natural, such as disease and weather damage. Hurricanes, for example, can break coral tissue, making it more susceptible to diseases.
But much of the problem can be traced to humans. "The man-made causes, the ones we can do something about, need to be taken extremely seriously," said study author Isabelle Cote, a biology professor at the University of East Anglia in Norwich, England.
"A lot of the important causes come from things people are doing on land, like pollution, sedimentation resulting from development and deforestation. They have very important repercussions," she said.

While the rate of coral loss is alarming now, it was even worse in the 1980s, researcher said. The report said there is no convincing evidence yet that global warming is responsible for the reef declines during the years studied, 1975-2000.
The majority of data came from four areas of intensive research; Florida, Jamaica, the U.S. Virgin Islands, and the Mesoamerican Barrier Reef system in Central America. The most dramatic damage to those regions occurred in the 1980s.

About 11 percent of coral reefs have been destroyed and another 16 percent are considered severely damaged, according to the researchers.

Coral reefs, which exist in shallow, tropical waters all over the world, are complicated eco-systems that provide homes to fish, crabs, urchins, sponges and other creatures.

When something happens to one species in a reef, it can affect many others, Cote said. In the early 1980s, for example, coral diseases coincided with the disappearance of the black spiny sea urchin, which had kept algae on the reefs in check.

Designating reef areas as marine sanctuaries can help protect them, but scientists say enforcement remains a big problem with so many different countries involved.
Because coral communities grow slowly, the recovery rate for areas now under protection remains unclear. The reef could rebound with just the hardiest of species, scientists said, creating a new reef community that functions differently from the earlier one.

"There is a lot of goodwill out there. What there isn't enough of is money," Cote said. She said hotels and resorts in the region that depend on scuba diving, snorkeling and eco-tourism are "shooting themselves in the foot" if they don't protect the fragile waters around them.

Most of Cote's research over the past 20 years has been in Barbados, a region where the coral has degraded dramatically over the past decade.

"Just from an economic standpoint, it makes sense to protect these areas," she said.

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NOAA RELEASES FIRST NATIONAL STUDY OF U.S. CORAL REEFS
New Report Ranks Harmful Threats, Highlights Key Actions

The first-ever national assessment of the condition of U.S. coral reefs was released today by the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration (NOAA). The report identifies the pressures that pose increasing risks to reefs, particularly in certain "hot spots" located near population centers. The report also assesses the health of reef resources, ranks threats in 13 geographic areas, and details mitigation efforts.

Led by NOAA’s National Ocean Service, the 265-page report, The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States, was developed by 38 coral reef experts and 79 expert contributors. Prepared under the auspices of the U.S. Coral Reef Task Force, the report establishes a baseline that will now be used for biennial reports on the health of U.S. coral reefs. NOAA has also released A National Coral Reef Strategy, a report to Congress outlining specific action to address 13 major goals, including continuing mapping and monitoring, to safeguard reefs. The reports will be highlighted when the U.S. Coral Reef Task Force meets on October 2-3, in San Juan, Puerto Rico.

NOAA scientists have already achieved a scientific milestone in mapping coral reefs. Working with public and private partners in Puerto Rico and the U.S. Virgin Islands, they successfully mapped coral ecosystems around those islands using a novel 26-category classification system and mapping process.
"The new classification is a vital management tool that tells us where the reefs are, what lives on them, and what relationships may be to neighboring habitats and human activities," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. "We now have a complete snapshot of the U.S. Caribbean region, a clear, consistent baseline for future mapping, and a solid model to implement good management in other regions."
The mapping process developed in the U.S. Caribbean is currently being applied in Hawaii, and then Guam, American Samoa and other U.S. territories with coral reefs.

Clear action is needed because an estimated 27 percent of the world’s shallow water coral reefs may already be beyond recovery. An estimated 66 percent are now severely degraded. Craig Manson, assistant secretary for fish and wildlife and parks, Department of the Interior, called release of the first national study of U.S. coral reefs "an important first report card on the health of U.S. reefs. It’s a valuable tool for raising public awareness about the global decline of these unique treasures," he said.

The report indicates that, in all areas, some U.S. reefs are in good to excellent health. But it also states that every U.S. reef system is suffering from both human and natural disturbances. U.S. reefs share problems with reefs globally, especially the effects of rapidly growing coastal populations. Over 10.5 million people now live in U.S. coastal areas adjacent to shallow coral reefs. Every year, 45 million people visit these areas.

While natural environmental pressures such as temperature, sea-level changes, diseases and storms have shaped coral reefs for at least thousands of years, human-induced pressures are now also taking their toll. Coastal pollution, coastal development and runoff, and destructive fishing practices are among the top-ranked threats. These are followed by ship groundings, diseases, changing climate, trade in coral and live reef species, alien species, marine debris, harmful tourist activity and tropical storms.

Overall, Florida and the U.S. Caribbean were found to be in the poorest condition, mainly because of nearby dense populations and the effects of hurricanes, disease, overfishing and a proliferation of algae. Live coral cover in the Florida Keys has declined 37 percent over the past five years. Of 31 coral reef fishery stocks in federal waters, 23 are overfished in the U.S. Caribbean. Coral disease is especially high in the Caribbean, where over 90 percent of the once abundant longspine sea urchins died in the early 1980s. Vital in keeping coral from being overgrown and killed by algae, they have since recovered to just 10 percent of their original numbers off the coasts of Florida, Puerto Rico and the U.S. Virgin Islands. In 20 years, white-band disease has killed nearly all the elkhorn and staghorn corals off the coasts of St. Croix, Puerto Rico and southeast Florida.

The report also details coral reef conditions in the Flower Garden Banks of the Northwestern Gulf of Mexico, Nassau, the Hawaiian Archipelago, American Samoa, Guam, the Commonwealth of the Northern Mariana islands and the Pacific Freely Associated States (Republic of the Marshall Islands, the Federated States of Micronesia and the Republic of Palau).

As ancient animals, corals evolved into modern reef-building forms over the last 25 million years. Today these living forms are earth’s largest biological structures. They are essential sources of food, jobs, chemicals, shoreline protection and life-saving pharmaceuticals. Tourism in U.S. coral reef areas generates over $17 billion annually. Commercial fishing generates an additional $246.9 million annually. In South Florida alone, reefs support 44,500 jobs, providing a total annual income of $1.2 billion.

Data and other information derived from NOAA’s coral reef efforts are now available at CoRIS, a new Coral Reef Information System Web site that provides a single point of access for nearly 20,000 aerial photos, navigational charts, photo mosaics, monitoring reports, professional exchanges and much more.

Co-chaired by the Secretary of Commerce and the Secretary of the Interior, the U.S. Coral Reef Task Force was established in 1998 to help lead U.S. efforts to address the coral reef crisis. It includes the heads of 11 federal agencies and governors of seven states, territories and commonwealths.

The Commerce Department’s National Oceanic and Atmospheric Administration (NOAA) is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of our nation’s coastal and marine resources.

To learn more about NOAA please visit http://www.noaa.gov The new reports and CoRIS Web site are available at http://www.coralreef.noaa.gov. Digital map products are available on CD-ROM and at http://biogeo.nos.noaa.gov.