FLOWER 

GARDEN 

BANKS

Coral reef condition:

A status report for the

2

0

20

GOOD Data: 2014–2018
1900's

Fishermen report the 

existence of the 

Flower Garden Banks.

1936

The U.S. Coast and Geodetic 

Survey confirms the existence 

of Flower Garden Banks.

1953

Oceanographer Henry Stetson 

discovers live corals on the banks.

Photo: Jan Hahn/Woods Hole 

Oceanographic Institution.

1974

Bureau of Land Management 

sets up protection zones to 

shield FGB from direct impacts 

of oil and gas activity.

1983

Region-wide die 

off of Long Spined 

Sea Urchins.

1984

FGB added to Site Evaluation 

List for sanctuary status after 

noted damage from anchored 

tug boat. 

1988

Long-term reef 

monitoring begins 

on FGB, continues to 

this day.

1950

First contour map 

of FGB published.

1960

First diving 

expedition. 

1976

Discovery of East 

Flower Garden 

Brine Seep.

1977

FGB nominated 

for sanctuary 

status.

1981

Oil and gas platform 

HIA-389-A constructed 

next to the East FGB.

1990

First mass spawning of 

corals reported at FGB; 

FGB’s first recorded 

bleaching event occurs.

1992

NOAA designates 

the FGB National 

Marine Sanctuary.

1985

Oil field service vessel anchored 

at bank; iconic book “Reefs and 

Banks of the Northwest Gulf of 

Mexico” published.

blue = general historic/government events and governance light blue = governance related to marine/reef management 

the resilience of one reef 

in a changing world

One hundred miles from the nearest beach in the Gulf 

of Mexico, Flower Garden Banks, a vast expanse of reef 

habitat, sits just below the ocean surface. These reefs 

are teeming with marine life and densely covered by large 

corals. Corals continue to thrive at Flower Garden Banks for 

three critical reasons: 

1. Distance from the shore reduces some human impacts 

such as water quality degradation; 

2. Its reefs sit in deeper, cooler waters than many coastal 

reefs, making corals less susceptible to events like coral 

bleaching; and,

3. The Flower Garden Banks are a designated national 

marine sanctuary, a status that offers additional 

protections to the benthic habitat such as enforcement 

of bans on anchoring, discharge, and bottom-impacting 

fishing activities.

While it benefits from isolation, this reef is not immune to 

the impacts other reefs across the globe experience today. 

Coastal runoff from extreme rain events, illegal fishing, and 

vessel anchoring still occur. Shifts in water temperature may 

induce bleaching events, and invasive species threaten the 

region's delicate food web dynamics. Yet, Flower Garden 

Banks has shown remarkable resilience to such impacts, 

and its protected status allows that resilience to endure.

Top: A school of Brown Chromis swim above a coral reef 

in Flower Garden Banks; Bottom: A diver collects coral reef 

monitoring photographs along transect tape.

Hurricanes help to shape the reefs on the Flower 

Garden Banks. Through direct observations after major 

hurricanes have passed close to the Flower Garden 

Banks National Marine Sanctuary, it is now generally 

acknowledged that these severe events are driving 

forces behind the general shaping of the reefs in the 

sanctuary. Mushroom heads are toppled, opening up 

reef space for recruitment, large barrel sponges are 

sheered, and yellow pencil coral fields that collapse in 

place recover over the subsequent years. 

Left: A satellite image of Hurricane Harvey over the Gulf 

of Mexico in 2017. Photo: NOAA.
reefs are under threat

While relatively cooler waters and greater depth shield 

the reefs of Flower Garden Banks somewhat from human 

impacts, they are still subjected to stressors stemming from 

both climate change and invasive species.

Climate Change

Climate change is considered the greatest global threat to 

coral reefs. Human-induced greenhouse gas emissions are 

accelerating ocean warming, and as a result, mass coral 

bleaching events and disease outbreaks are becoming 

more frequent. Warmer oceans increase the likelihood of 

more frequent and intense hurricanes, which also amplifies 

impacts to reefs. Excess carbon dioxide absorbed by the 

oceans alters seawater chemistry by decreasing the pH, 

impacting the ability for corals to calcify and build reefs. 

Even with the remote location of Flower Garden Banks, 

coral bleaching and the spread of disease remain major 

management concerns. In 2005, 2010, and 2016, Flower 

Garden Banks suffered major bleaching, though without 

significant mortality. Fortunately, so far they have been 

spared a major disease outbreak. 

Invasive Species

Several invasive species have been reported at Flower 

Garden Banks National Marine Sanctuary, including 

lionfish. Lionfish began appearing in the Gulf of Mexico in 

2009, about 20 years after they entered the Atlantic as an 

invasive species. By July 2011, lionfish were observed on 

all three banks of the sanctuary. Lionfish have a voracious 

appetite, venomous spines, and reproduce rapidly. Without 

any natural predators in the region, lionfish can overwhelm 

native fish and invertebrate populations.

Water temperature

Healthy corals have a symbiotic relationship with 

microscopic algae called zooxanthellae that live in their tissue. 

These algae produce the coral’s primary food source 

and give them their color. When ocean water is too warm , 

corals expel their algae, rendering the coral tissue translucent 

and making the animal's white skeleton clearly visible . 

These events are called coral bleaching because its now stark 

white appearance makes it look as though the coral has been 

"bleached" of color (in addition to having lost its main food 

source). Corals can survive a bleaching event and recruit new 

algae, but repeated events cause stress and decrease colony 

health, leading to coral death.

what you can do to help

Flower Garden Banks is a treasure in the Gulf of Mexico. Here are things you can do to help protect 

this important place:

Don’t stand on or touch live 

coral. Don't take pieces of 

corals home with you.

Only catch enough fish for 

you and your family. If you 

don't fish, choose seafood 

that is sustainably harvested.

Support your 

local aquarium.

Reduce energy 

use and your 

carbon footprint.

Educate yourself about 

coral reefs and the 

creatures they support.

Support initiatives that 

preserve and protect 

coral reefs.

1995

Oil spill notifications 

mandated following 

spill risk assessments.

1996

Stetson Bank added 

to FGB National 

Marine Sanctuary.

1997

A new species, the 

Mardi Gras Wrasse, 

is first observed.

1998

Coral bleaching and 

recovery occurs at 

FGBNMS.

2002

First observation of 

potentially invasive 

Orange Cup Corals.

2003

Live elkhorn coral is 

discovered at West 

Flower Garden.

2005

Coral bleaching and 

recovery; Hurricanes 

Katrina and Rita strike 

the Gulf of Mexico.

2006

Fossil Acropora reefs 

discovered below 

current coral cap.

2008

The research vessel 

Manta begins service; 

another coral bleaching 

event occurs.

2010

Extensive coral bleaching 

occurs at FGBNMS; 

though corals recover.

2011

Lionfish, an invasive 

species, first 

observed at FGBNMS.

2016

Localized mortality event occurs 

at East FGB; FGBNMS experiences 

coral bleaching and recovery.

2018

Upper 65ft of HI-A-389-A gas platform 

within boundaries of East FGB removed; 

the Regal Demoiselle, an exotic species, 

is sighted for the first time at FGBNMS.

pink = social/economic green = biology and hurricanes
1989 time-lapse imaging 

helps monitor 

long-term coral 

growth

Long-term coral reef monitoring was first 

established at Flower Garden Banks in 1988. Due 

to the close proximity of these reefs to oil and gas 

activity, the federal agency regulating this industry 

has been an active partner since monitoring began. 

In the subsequent three decades, regular and 

consistent monitoring shows that reefs within the 

selected one-hectare study sites have maintained 

high coral cover. This high coral cover continues 

to support relatively diverse and abundant fish 

populations in addition to a variety of other marine 

species. Within the long-term monitoring study 

sites, such as in the example provided to the right, 

permanent photostations have provided a timelapse sequence of images from 1989 to 2019. 

giants roam the reef

Flower Garden Banks is home to both year-round 

and seasonal megafauna—a category of large, 

charismatic animals that include sea turtles, manta 

rays, spotted eagle rays, and sharks. Loggerhead 

sea turtles (C. caretta) can often be spotted coming 

up for air or resting underneath complex coral 

structures. Approximately 20 species of sharks 

and rays can be found within the sanctuary as well. 

Schooling scalloped hammerhead sharks (S. lewini) 

and spotted eagle rays (A. narinari) are wintertime 

visitors, while summer months usually bring whale 

sharks (R. typus), the largest fish in the ocean with 

a typical length of over 30 feet (9m). Manta rays (M. 

birostris) that regularly frequent the sanctuary are 

easily identifiable via unique underbelly markings 

(think of it as a fish “fingerprint”). Approximately 100 

individual manta rays observed within the sanctuary 

have been photographed and catalogued to date 

as part of an ongoing project, and both researchers 

and recreational SCUBA divers are encouraged to 

submit their images to help photo-tag and track 

manta rays roaming the national marine sanctuary.

1989

2010

1996

2019

This series, taken from a photostation at East Flower 

Garden Bank, documents increasing coral cover over time. 

Images are from 1989 (top left), 1996 (top right), 2010 

(bottom left), and 2019 (bottom right).

Top: A manta ray shows its distinct underbelly pattern; 

Bottom: A loggerhead sea turtle observed in the sanctuary.
N 0 2 Miles

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1

Kilometers

FLOWER GARDEN BANKS CORAL REEFS ARE IN GOOD CONDITION

Herbivory

Adult coral

Diversity

Coral cover

Mortality

CCA cover

Macroalgae

Temperature

stress

Ocean

acidification

Reef material

growth

FISH

CORALS

& ALGAE

CLIMATE

89

Diversity

Reef fish

Sustainability

The East and West Flower Garden Banks are submerged topographic features off the shores of Texas and Louisiana in 

the Gulf of Mexico. Rising from over 150 m depth to 17 m below the sea surface, they harbor relatively deep coral reef 

ecosystems. They were first discovered in the early 1900's and designated as part of the Flower Garden Banks National 

Marine Sanctuary in 1992. This report combines data collected from both East and West Flower Garden Banks and 

evaluates their condition for corals & algae, fish, and climate. Human Connection indicators were not assessed as Flower 

Garden Banks are not immediately adjacent to a permanent human population. Overall, coral reefs within Flower Garden 

Banks are in good condition (score: 89%), meaning the reefs are lightly impacted overall. Coral & algae are in very good 

condition. Fish and climate are in good condition overall, meaning fish and climate indicators are lightly impacted. Reef 

material growth is in very good condition. 

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1

Kilometers

west flower garden bank

east flower garden bank

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Kilometers

Coral reef habitat

Deep coral reef habitat

Surveyed coral reef habitat

Sea surface

Whenever we conduct ecosystem assessments, we need to determine an appropriate baseline to make comparisons 

against current data. Ideally, we would assess the state of coral reef ecosystems by comparing current information to 

data collected before coral reefs were facing the impacts of climate change, overfishing, and pollution. Unfortunately 

for many reefs, data were only recently collected, and such comparisons cannot be made. Data used in this status 

report from 2014 to 2018, as well as information on reef conditions at Flower Garden Banks collected since the 1970's, 

suggest that with the exception of some fishing impacts, current reef conditions may largely reflect pre-industrial 

conditions. That scientists have to make several considerations before setting a historical baseline is reflective of the 

"Shifting Baseline" theory. Shifting baselines highlight the difficulty of interpreting change when we gauge the current 

state of an ecosystem against a prior baseline. There is the chance that the ecosystem we want to observe may have 

already changed, or "shifted", significantly between an earlier baseline and the one we have set. How far back we set 

our baseline depends on the amount of historical data available to make accurate comparisons.

Since 1988, a complementary long-term monitoring program at the Flower Gardens National Marine 

Sanctuary has consistently tracked the status of these and other indicators. More information 

about the sanctuary itself and the data collected by sanctuary scientists can be found at https://

flowergarden.noaa.gov/welcome.html. 

N 0 2 Miles

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1

Kilometers

Land

Gulf of Mexico

What do the scores mean?

80–89% Good

Most indicators meet reference values. 

Conditions in these locations are lightly 

impacted or have lightly declined.

70–79% Fair

Some indicators meet reference values. 

Conditions in these locations are moderately 

impacted or have declined moderately.

All or almost all indicators meet reference values. 

Conditions in these locations are unimpacted, or 

minimally impacted or have not declined.

90–100% Very Good

60–69% Impaired

Few indicators meet reference values. 

Conditions in these locations are very impacted 

or have declined considerably.

0–59% Critical

Very few or no indicators meet reference values. 

Conditions in these locations are severely 

impacted or have declined substantially.

Insufficient Data

Not scored.
Each year, about 7–10 days after the August full moon, a 

massive coral spawning event occurs in Flower Garden 

Banks. Described as an upside down underwater snow 

storm, coral species will release their gametes in a 

synchronized display known as broadcast spawning. 

This, in addition to the sheer volume of gametes released, 

optimizes the likelihood of genetic diversity in the new 

generation of coral larvae. Some species release gamete 

bundles that encapsulate both egg and sperm, while 

other species have separate male and female colonies. 

Whether fledgling larvae disperse or settle near their 

parent reefs will depend on the direction and/or strength 

of the ocean current. 

The cues that trigger coral spawning are not well 

understood, but it is fairly certain that the rhythm of 

the lunar and solar cycles, as well as changes in water 

temperature and ocean chemistry, play a role. Mass coral 

spawning was first observed at Flower Garden Banks in 

1990. Since then, researchers have observed the event 

each year to collect more data on timing and species 

participation. Stressed corals do not have the energy to 

reproduce; so the presence of a predictable and abundant 

spawning event is a strong indicator of a healthy coral reef.

healthy corals spawn 

the next generation

Top: An Orbicella star coral releases its gamete 

bundles during the mass spawning event; Bottom: 

Gamete bundles drift away from their parent corals.

key themes &indicators

Climate

Climate affects all components of a reef 

system. Climate change and ocean acidification 

influence reefs across the globe, but conditions 

vary at the regional and local level. The climate 

indicators are:

• Temperature stress, which evaluates the frequency and 

severity of high temperature events.

• Ocean acidification, which indicates if the water 

chemistry is suitable for the growth of corals 

and other calcifiers.

• Reef material growth, which is a calculated 

measurement of the yearly gain or loss of 

three-dimensional reef habitat. 

fish

Coral reefs serve a vital ecological role for fish 

species. Fish are important to the ecology of the 

reef, the economy, and the livelihoods of local 

communities. The indicators for fish are:

• Reef fish, a region-specific measure of density for 

selected fish species.

• Sustainability, a measure of human-related fish 

mortality relative to natural fish mortality.

• Diversity, a measure of unique fish species present.

Corals & algae make up the base of the coral 

reef ecosystem, providing food and shelter 

for fish, shellfish, and marine mammals. The 

indicators for corals & algae are: 

• Coral cover, a measure of what percentage of the 

bottom (benthos) is living stony coral.

• Macroalgae cover, a measure of what percentage of 

the bottom (benthos) is macroalgae.

• Crustose coralline algae (CCA) cover, a measure of 

what percentage of the bottom (benthos) is crustose 

coralline algae.

• Adult coral, a measure of the density of reproductive 

age coral species. 

• Herbivory, a measure of the level of grazing pressure by 

fish on corals and algae.

• Mortality, a measure of the amount of old dead coral 

skeleton exposed as scars on live coral colonies.

• Diversity, a measure of unique coral species present.

Corals & algae
TX LA

MS AL

West Flower Garden Bank

East Flower Garden Bank

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0 4 8 2 Miles

Status report working group

Mark Belter, Jeremiah Blondeau, Caroline Donovan, 

Kimberly Edwards, Ian Enochs, Nate Formel, Erick Geiger, 

Steve Gittings, Jay Grove, Sarah Groves, Emma Hickerson, 

Michelle Johnston, Heath Kelsey, Kathryn Lohr, Nathan 

Miller, Marissa Nuttall, G.P. Schmahl, Erica Towle, and 

Shay Viehman. 

About this status report

This status report is a joint product of NOAA's Coral 

Reef Conservation Program (CRCP), Flower Garden 

Banks National Marine Sanctuary, and the University of 

Maryland Center for Environmental Science. Science 

communication, design, and layout by Nathan Miller, 

Caroline Donovan, Heath Kelsey, Max Hermanson, and 

Annie Carew. March 2020.

Acknowledgements

The CRCP supports effective management and sound 

science to preserve, sustain, and restore valuable coral 

reef ecosystems for future generations. For more 

information, visit coralreef.noaa.gov.All photos, from 

NOAA/Office of National Marine Sanctuaries/Flower 

Garden Banks National Marine Sanctuary unless specified 

otherwise. Cover photographed at East Flower Garden 

the success of national 

marine sanctuaries

Bank in 2012 by George Schmahl. 

The views and conclusions contained in this document 

are those of the authors and should not be interpreted 

as representing the opinions or policies of the U.S. 

Government or the National Fish and Wildlife Foundation 

and its funding sources. Mention of trade names 

or commercial products does not constitute their 

endorsement by the U.S. Government, or the National 

Fish and Wildlife Foundation or its funding sources.

Flower Garden Banks National Marine Sanctuary was 

designated in 1992 to help protect the sanctuary's coral 

reef habitat and wildlife from adverse human impacts. The 

combination of location and geology makes Flower Garden 

Banks an extremely productive ecosystem. Salt domes 

push the seafloor up to within 17 meters (53ft) of the ocean 

surface. The sanctuary boundaries encompass a variety of 

habitats down to approximately 150 meters (500ft), and life 

flourishes at every depth, with a variety of reef fish, corals, 

and other marine invertebrates. 

The status report working group during the workshop in 

Silver Spring, MD in June 2019.

Massive boulders of brain and star corals flourish at Flower 

Garden Banks National Marine Sanctuary.

Despite a global decline in coral reef habitat, Flower Garden 

Banks continues to thrive thanks both to their remote 

offshore location and proximity to cooler waters from 

the deep. While these conditions shield this reef system 

somewhat from human impacts, Flower Garden Banks 

is not invulnerable. Therefore, continued observation and 

conservation of this habitat remains crucial as life on 

Flower Garden Banks still faces threats related to climate 

change, invasive species, water quality degradation, and 

unsustainable human activities.

NOAA is proposing to expand Flower Garden Banks 

National Marine Sanctuary to protect additional habitat in 

the northwestern Gulf of Mexico. Currently, the sanctuary 

protects three banks among dozens along the edge of 

the continental shelf. This expansion would help further 

conserve underwater habitat, endangered species, and 

nursery grounds for commercially viable fish.

why a status report?

Effective coral reef conservation cannot be accomplished 

without an informed and engaged public. This status report 

is part of an ongoing series of documents to track the status 

and trends of coral reefs across the U.S. and its territories. 

The Flower Garden Banks coral reef status report is part of 

a larger effort to provide the public and decision-makers 

with information that helps us manage and conserve coral 

reef ecosystems.

This status report provides a geographically specific 

assessment of Flower Garden Banks coral reef 

condition between 2014–2018. Data were collected by 

NOAA’s National Coral Reef Monitoring Program. For 

more detailed information on methodologies, indicators, 

thresholds, and scoring, visit http://www.coris.noaa.gov 

(keyword: status reports).

Status report working group members at Flower Garden 

Banks National Marine Sanctuary offices in Galveston, TX.