ACCESS NUMBER: 00011

STUDY TITLE: Long-Term Monitoring at the East and West Flower Garden Banks 

National Marine Sanctuary (2011–2012). 

REPORT TITLE: Long-Term Monitoring at the East and West Flower Garden Banks 

National Marine Sanctuary, 2011–2012. Vol. I, Technical Report; Vol. II, Appendixes. 

CONTRACT NUMBER: NOAA and BOEM Interagency Agreement No. M09PG00011. 

SPONSORING OCS REGION: Gulf of Mexico 

APPLICABLE PLANNING AREA(S): GOM- Western Planning Area 

FISCAL YEAR(S) OF PROJECT FUNDING: 2012; 2013 

COMPLETION DATE OF REPORT: March 2015 

COSTS: 2012: $219,100; 2013: $181,213 

PROJECT MANAGER(S): Michelle A. Johnston, Ph.D. 

AFFILIATION: NOAA Flower Garden Banks National Marine Sanctuary. 

ADDRESS: 4700 Avenue U, Bldg. 216, Galveston, TX 77551. 

PRINCIPAL INVESTIGATOR(S)*

: R.J. Eckert, J.A. Embesi, E.L. Hickerson, M.A. 

Johnston, M.F. Nuttall, G.P. Schmahl, N.C. Slowey 

KEY WORDS: Bleaching, Gulf of Mexico, Flower Garden Banks, marine sanctuary, 

monitoring, coral reef, observations, water quality. 

BACKGROUND: Since 1995, the National Oceanic and Atmospheric Administration’s 

(NOAA) Flower Garden Banks National Marine Sanctuary (FGBNMS) has partnered 

with the Bureau of Ocean Energy Management (BOEM) to monitor the health of the 

coral reefs of the East and West Flower Garden Banks (FGB). Located 193 and 172 km 

(East and West Flower Garden Banks, respectively) offshore from Galveston, Texas, 

the banks are remotely located topographic features on the outer continental shelf in the 

Gulf of Mexico that are capped with reef-building corals. The monitoring program was 

developed over a period beginning in the late 1970s, when BOEM recognized the need 

for a baseline assessment of the status of the coral reefs in anticipation of increased 

exploration and development of offshore oil and gas resources in the area. 

OBJECTIVES: To assess the health of the East FGB and West FGB coral reefs, 

through the evaluation of changes in living coral and other benthic community cover, 

coral growth rates, reef fish population dynamics, water quality, and other indices of reef 

vitality.
ACCESS NUMBER: 00000 

DESCRIPTION: The benthos (with an emphasis on coral cover and algae) was 

examined along stationary repetitive photoquadrats to monitor changes in specific coral 

reef locations over time, and random transect lines were photographed to get estimates 

of coral cover. Sclerochronology was used to document the accretionary growth rate of 

Montastraea faveolata colonies, and photography was used at permanent stations to 

monitor the lateral growth of corals. General aspects of coral condition were 

documented along perimeter lines at the EFGB and WFGB. During each annual 

monitoring cruise, observations of general coral reef health, as well as notable biological 

and oceanographic events were qualitatively assessed and documented. Water quality 

parameters (including seawater temperature and salinity) were recorded using SeaBird 37-SMP MicroCAT datasondes to characterize the reef caps and water column 

environment of the FGBNMS. Fish surveys using the Bohnsack and Bannerot method 

were conducted at randomly located stations and sea urchin and lobster surveys were 

conducted along the study site perimeter lines. 

SIGNIFICANT CONCLUSIONS: In more than 25 years of continuous monitoring, the 

coral reefs of the FGBNMS have maintained high levels of coral cover, suffered 

minimally from hurricanes, coral bleaching, and disease outbreaks, and supported 

relatively diverse and abundant fish populations as well as other vertebrate and 

invertebrate species. No significant long-term changes have been detected in coral cover 

or diversity at the FGB during monitoring efforts that have taken place since 1988, and 

likely not since the first measurements were made in the early 1970s. Based on the 2011 

and 2012 data, the average coral cover on the FGB coral caps was 60%. The incidence 

and prevalence of disease and bleaching in comparison to other western Atlantic coral 

sites were low. 

STUDY RESULTS: Based on the results of the random transect data, Orbicella franksi

was the principal component of mean percent coral cover at both banks. Mean cover of 

Orbicella franksi at EFGB was estimated at 26% in 2011 and 26% in 2012. At WFGB, 

mean cover was 24% in 2011 and 26% in 2012. Pseudodiploria strigosa was the next 

most abundant species during this period, with 6% at EFGB in 2011 and 8% in 2012. 

WFGB estimates were 12% and 9% for the two years. The importance of the FGB, in 

terms of the Atlantic coral reef system as a whole, has been substantially elevated due 

to the NOAA Fisheries Endangered Species Act listing of all coral under the Orbicella 

annularis species complex as threatened, all of which are found at the FGB. 

In 2011 and 2012, macroalgae mean percent cover was more abundant than crustose 

coralline algae, fine turf algae, and bare rock (abbreviated as Crustose/Turf/Bare or 

CTB), ranging from approximately 30–38% at EFGB and 29–31% at WFGB. Despite 

continued stability in mean coral cover, macroalgae mean cover has been increasing 

since 1999. The most dominant components of macroalgal cover were fleshy algae, 

Dictyota spp., and Lobophora variegata. CTB was the second-ranked non-coral 

category of mean substratum percent cover, ranging from approximately 9–12% at 

EFGB and 10–12% at WFGB from 2011 to 2012. Mean sponge cover continues to be 

extremely low at both banks (less than 1%). An ANOVA and ANOSIM revealed that no 
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significant differences between sites or years occurred at EFGB and WFGB, making the 

banks similar in terms of benthic composition. 

Sclerochronology was used to measure the accretionary extension rates of Orbicella 

faveolata coral cores. Annual extension of Orbicella faveolata at EFGB averaged 6.5 

mm/year (sample range = 4.6–9.6 mm/year). At WFGB, annual growth averaged 5.6 

mm/year (range = 3.3–10.3 mm/year). Extension rates did not differ significantly 

between banks. 

Repetitive quadrats stations were photographed in 2011 and 2012 to monitor 

changes in specific coral reef locations over time. Mean coral cover in the repetitive 

quadrats averaged approximately 63% for both banks in all years. Macroalgae and 

CTB cover showed reciprocal patterns between banks. An ANOVA on the 

proportional cover of sponge and CTB showed significant differences between both 

bank and year. The incidences of bleaching, paling, and fish biting were low 

(ranging from 0.00–0.63% of area assessed), and there was little evidence of coral 

disease. The coral assemblages remained consistent at both banks, with the 

dominant corals being Orbicella franksi and Pseudodiploria strigosa. 

At repetitive photostations in 32–40 m depths, mean coral cover ranged between 72-

76% in 2011 and 2012. Orbicella franksi and Montastraea cavernosa were the 

dominant species in this depth range. Macroalgae averaged 19% and CTB averaged 

7%. 

Seawater temperature and salinity were recorded at EFGB and WFGB using Sea-Bird 

37-SMP MicroCAT datasondes from 2011 to 2012. During the 2011 to 2012 period, 

seawater temperature ranged from 18.62°C to 30.49°C from 2011-2012 at EFGB, and 

ranged from 17.92°C to 30.55°C at WFGB. High seawater temperatures were observed 

during the late summer months, exceeding the 30°C coral bleaching threshold; 

however, because only limited time was spent above this temperature, the risk of 

bleaching was low. Though most Chl-a and nutrient concentrations were below 

detectable limits, total Kjeldahl Nitrogen (TKN) was detected in all water samples 

collected at the banks in 2011, with concentrations ranging from 1.3–45.2 mg/l (above 

the 0.55 mg/l detection limit), and in 50% of the samples collected in 2012. 

Fish surveys were conducted using a modified Bohnsack and Bannerot (1986) method 

in 2011 and 2012. Pomacentridae, Labridae, and Serranidae were the dominant fish 

families at both banks. Diversity varied between banks and years, with the greatest 

diversity occurring at WFGB in 2012. The most frequently sighted species during this 

study period were brown chromis (Chromis multilineata), closely followed by Spanish 

hogfish (Bodianus rufus), and bluehead (Thalassoma bifasciatum). Mean fish density 

(abundance per 100 m2

) was highest at WFGB in 2012 and lowest at EFGB in 2012. 

Invertivores were the dominant fish guild, with Pomacentridae and Labridae 

representing the largest density. The size-frequency distributions of invertivores were 

non-normally distributed, with the majority of individuals being small damselfish. The 
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greatest mean biomass was seen at WFGB in 2011, where the piscivores possessed 

the highest mean biomass for all surveys, with over 50% of total biomass. Following the 

pattern of coral species present at the FGB (low diversity compared to Caribbean reefs, 

but high coral cover), the fish assemblages reflect a similar trend of low diversity and 

high abundance (Pattengill-Semmens and Gittings 2003). Although no lionfish (Pterois

spp.) were observed within the fish surveys conducted, lionfish were sighted within the 

study site in 2012 after first being observed to invade sanctuary waters in 2011. 

Sea urchin surveys documented continued low densities of Diadema antillarum at 

WFGB in 2011 (3.75 per 100 m2) and 2012 (12.5 per 100 m2). No sea urchins were 

observed at EFGB. These populations have not recovered to pre-1984 levels, which 

were at least 140 per 100 m2 at EFGB and 50 per 100 m2 at WFGB (Gittings et al. 1998). 

STUDY PRODUCT(S): 

Johnston, M.A., M.F. Nuttall, R.J. Eckert, J.A. Embesi, N.C. Slowey, E.L. Hickerson, 

and G.P. Schmahl. 2015. Long-term monitoring at East and West Flower Garden 

Banks National Marine Sanctuary, 2011–2012, volume 1: technical report. U.S. 

Dept. of Interior, Bureau of Ocean Energy Management, Gulf of Mexico OCS 

Region, New Orleans, Louisiana. OCS Study BOEM 2015-027. 194 p. 

Johnston, Michelle A., M.F. Nuttall, R.J. Eckert, J.A. Embesi, N.C. Slowey, E.L. 

Hickerson, and G.P. Schmahl. 2015. Long-term monitoring at East and West 

Flower Garden Banks National Marine Sanctuary, 2011–2012, volume 2: 

appendixes. U.S. Dept. of Interior, Bureau of Ocean Energy Management, Gulf of 

Mexico OCS Region, New Orleans, Louisiana. OCS Study BOEM 2015-028. 416 

p. 

 

*

P.I.’s affiliation may be different than that listed for Project Manager(s).