Jean-Michel Cousteau: Ocean Adventures
Receive updates & news:
Guide to America's National Marine Sanctuaries

The map, slideshow and video requires Flash 6 or higher to play.

If you need to install Flash, you can do so for free from here.

Voyage to Kure
Sharks at Risk
The Gray Whale Obstacle Course
  flower garden

Return to the Amazon
Sea Ghosts: Belugas
Call of the Killer Whale

Reef-Building Corals

Featured Creature
Reef-Building Corals

Reef-building corals are marine animals and the chief architects of coral reefs. The coral animal body, called a polyp, is essentially round, with a mouth in the middle. Coral polyps secrete a hard skeleton made of calcium carbonate under their skin; this skeleton attaches the coral to the solid surface where it lives. Corals can reproduce polyps via asexual cloning, resulting in the colonizing pattern of coral reefs. Reef-building corals tend to live 150 feet below the surface, although some can live deeper. Most live in warm water. Many corals live in symbiosis with zooxanthellae, a type of algae that they feed on. Hundreds of species of reef-building corals exist, varying widely in color, size and shape.

Flower Garden Banks National Marine Sanctuary

Official Web Site (at
Sanctuary Map (at
Encyclopedia of the Sanctuary (at

Flower Garden Banks got its name from snapper fishermen at the turn of the last century, who compared the corals and sponges they could see below the ocean's surface to familiar flowers. As a regional oasis for shallow-water Caribbean reef species, the area represents the great biological diversity and beauty that prompted researchers and recreational divers to seek protection for the Flower Gardens in 1972. After a 20-year effort, Flower Garden Banks was designated a National Marine Sanctuary in 1992. The sanctuary originally included just the East and West Flower Garden Banks. Stetson Bank was added to the sanctuary in 1996 as part of the reauthorization of the National Marine Sanctuaries Act. Each of these three banks has its own distinct sanctuary boundaries.

What's Underwater
Located 105 miles south of the Texas-Louisiana border, the Flower Gardens are the northernmost coral reefs in the United States. The banks themselves are surface expressions of two salt domes whose formation began 160 to 170 million years ago, in what was then a shallow sea. The reef community is believed to be 10,000 to 15,000 years old. An oasis for reef-dwellers, the Flower Gardens are 400 miles from the nearest tropical coral reef, which is off the coast of Tampico, Mexico. Stetson Bank is a third salt dome, located 70 miles south of Galveston, Texas, where the water is cooler, and corals do not thrive. Instead, this bank supports a coral and sponge habitat and rich assemblages of associated animals and plants. In total, almost 300 species of fish have been documented in the sanctuary's waters as well as dozens of coral species, three sea turtle species, and a host of other marine life, including sponges, lobsters, crabs, birds, dolphins, sharks and whales.


Due to the susceptibility of coral reefs to damage from human impact, the sanctuary does not actively encourage visits, but neither are visitors discouraged. The sanctuary strongly urges those who do visit to practice appropriate reef etiquette.

Several commercial dive operators take people out to the sanctuary and to surrounding oil and gas platforms. Visibility usually ranges from 75 to 150 feet, providing for great dives even on the worst days. With water temperatures from the mid-60s to the mid-80s, the sanctuary is a premier diving destination.


Research Projects

  • Deepwater Habitat Characterization
    Historically, research at the sanctuary has focused on the coral reef caps, which account for only 1 percent of the entire sanctuary and are easily accessible with scuba equipment. More recent efforts have focused on deepwater exploration (below 170 feet), using multibeam side-scan sonar, submersibles and remotely-operated vehicle. These surveys enable researchers to better understand the biodiversity, habitats, resources and ecological processes impacting the sanctuary environment.
  • Whale Shark and Manta Ray Tagging
    The sanctuary has been working with Rachel Graham of the Wildlife Conservation Society to track and tag whale sharks and manta rays in the sanctuary. To date, two mantas have been tagged, and acoustic receivers have been placed at all three banks. Additional tagging is planned.
  • Conch Tagging
    Queen conchs are the focus of research being conducted by Craig Burnside of Bainbridge College in Georgia. Small metal identification tags are attached to wire wrapped around the crown of the shell. This research assesses populations, establishes ranges and identifies the life-history stages of these mollusks within the sanctuary.
  • Long-Term Monitoring
    In 1972, concerns about oil and gas production in the Gulf of Mexico prompted monitoring studies of the coral reef habitats at the East and West Flower Garden Banks, which continue to this day. Similar studies were initiated at Stetson Bank in 1993.

Challenges Facing the Sanctuary

  • Lack of public awareness of the resource.
  • Lack of understanding of the human impacts on this resource.
  • Regional water quality.
  • Coral disease and bleaching.
  • Remote location that makes daily management difficult.
  • Increasing use by a variety of groups.

Success Stories

  • The sanctuary was designated a No Anchor Zone in 2001 by the International Maritime Organization. This is the first time such designation was given to a coral reef habitat.
  • Deepwater habitat characterization has revealed that some reefs may be connected to other banks in the northern Gulf of Mexico through a series of low reef ridges that were previously unknown.
  • Detailed habitat maps produced by the sanctuary have helped raise the protection level for sensitive and unique habitats surrounding the sanctuary.
  • The sanctuary is the site of one of the longest continuous monitoring studies of a coral reef ecosystem anywhere in the world.