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East Flower Garden Banks

Photo credits: İFrank and Joyce Burek; Source:
From: Rezak et al., 1985; NOAA, 2002

The Flower Garden Banks National Marine Sanctuary (FGBNMS) is located in the Northwest Gulf of Mexico, approximately 192 km southeast of Galveston, Texas. The East Flower Garden is at 27.9°N latitude and 93.6°W longitude. It is pear-shaped and covers an area of about 67 square km. It is home to a wide array of marine life, including numerous species of rays and sharks, sea turtles and marine mammals, over 170 species of fish and approximately 300 species of reef invertebrates. The salt dome underlying the bank has furnished the framework for coral reef development, as well as providing a reservoir for oil and gas resources. Within a four-mile radius of the Flower Garden Banks, there are currently 10 production platforms and there is one gas production platform within the East Sanctuary boundary.

East Flower Garden Banks

Location on Continental Shelf:   Outer-Shelf Bank
Coordinates:   28.00° N   93.58° W
Nearest Largest City:   Galveston, Texas, USA

Selected Characteristics:
Area of Coverage:   66 km2
Width:   5.2 km
Length:   8.7 km
Minimum Depth:   20 m
Maximum Depth:   136 m
Minimum Temperature:   20oC
Maximum Temperature:   30oC
Minimum Salinity:   31 ppt
Maximum Salinity:   36 ppt

Community Structure:
Structurally, the Flower Garden Banks coral reefs are composed of large, closely-spaced heads up to three or more meters in diameter and height. Coral cover averages 47% and is frequently cavernous. Other prominent benthic components include coralline algae covered rocks, leafy and filamentous algae and sponges, with sand at the bottom. Dominant coral species are the boulder star coral (Montastrea annularis), symmetric brain coral (Diploria strigosa), mustard hill (Porites astreoides) coral and the great star coral (Montastrea cavernosa). Algal populations have historically been low, but blue-green algae are becoming abundant and invading open space on coral heads. Recently, a red or blue green turf algal mat was observed. In spite of their northern location, the abundance and growth rates of hermatypic corals are similar to those on Caribbean reefs. The absence of shallow-water alcyonarians at the Flower Gardens, however, sets these reefs apart from all other Atlantic coral reef communities.

Geological Characterization:
The East Flower Garden Bank is the surface expression of salt diapers capped by living coral reefs at the crests. The major fault trends are west-northwest to east-southeast, with minor trends toward the northeast and the southeast. North-south profiles show the faulting to be steplike, upslope. Down-faulting is typical of the tensional fractures produced during the domal uplift of sedimentary rocks over salt domes. The central graben has developed partly because of tensional stresses developed during uplift and of removal of salt from the crest of the ridge by dissolution. Total relief on the bank is approximately 116 m. Slopes are steep on the east and south sides of the bank and gentle on the west and north sides. The shallowest depth on the bank is about 20 m. The surrounding waters depths are about 100 m to the west and north and about 120 m to the east and south. An elongate depression in the north central part has a depth of 136 m. A short distance to the southeast of the East Flower Garden Bank is a brine seep complex. This is about 67 m deep, forms an underwater salt lake about 30 m in diameter and about 0.3 m deep.

Flower Garden Banks National Marine Sanctuary.2003. URL:

Gardener, J.V., L.A. Mayer, J.E.H. Clarke and A. Kleiner.1998. High-Resolution Multibeam Bathymetry of East and West Flowe Gardens and Stetson Banks, Gulf of Mexico. Gulf of Mexico Science XVI No. 2:128.

NOAA. 2002. The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States. URL:

Rezak, R., T.J. Bright and D.W. McGrail. 1985. Reefs and Banks of the Northwestern Gulf of Mexico: Their geological, biological, and physical dynamics. Wiley, New York, NY, USA, 259 p.

Additional Information:
National Marine Sanctuaries
Flower Garden Banks National Marine Sanctuary
Gulf of Mexico Region - Environmental Information
GEMS - Flower Garden Banks National Marine Sanctuary
The National Marine Sanctuaries

Keywords:   Ray, Shark, Turtle, Coral, Reef, Bank, Salt dome, Oil and gas

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