Flower Garden Banks National Marine Sanctuary: Summary of Resource Conditions

The various resource status and trend evaluations presented in this report are summarized below. Each question used to rate the condition of and trends in sanctuary resources is listed, followed by:

1. A set of rating symbols that display key information. The first symbol includes a color and term to indicate status, the next symbol indicates trend, and a shaded scale adjacent to both symbols indicates confidence (see key for example and definitions).
2. The status description, which is a statement that best characterizes resource status and corresponds to the assigned color rating and definition as described in Appendix A. The status description statements are customized for all possible ratings for each question.
3. The rationale, which is a short statement or list of criteria used to justify the rating.

Key:

Pressures

What are the levels of human activities that may adversely influence water quality and how are they changing?

All Sanctuary Areas

Status Description: Some potentially harmful activities exist, but they have not been shown to degrade water quality.

Rationale: The number of oil and gas platforms in the Gulf of Mexico has declined over time, and reported spill incidents from platforms in the lease areas overlapping Flower Garden Banks National Marine Sanctuary also decreased during the study period. The number of reported spill incidents from vessels varied without trend, but spills from all sources declined overall. No military activities that have the potential for any significant adverse impacts occur within the sanctuary. There is some evidence to suggest that nutrients and other contaminants from land-based runoff or wastewater contamination may reach the sanctuary following large storm events.

What are the levels of human activities that may adversely influence habitats and how are they changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Some potentially harmful activities exist, but they have not been shown to degrade habitat quality.

Rationale: Only one dive charter operated in the area, which limited the number of divers in the sanctuary. Though surrounded by oil and gas structures, the number of platform installations declined and the number of platform removals increased. There were some fishing gear impacts, as evidenced from discarded legal and illegal fishing gear, but the extent of these is not well understood. Discarded anchors were found on the seafloor, but are not believed to have caused recent impacts. Research activities can have localized impacts, as can the installation of mooring buoys, but their benefits far outweigh these impacts.

Expansion Banks

Status Description: Some potentially harmful activities exist, but they have not been shown to degrade habitat quality.

Rationale: While some fishing gear impacts occurred, as evidenced by discarded legal and illegal fishing gear observed on the seafloor, the level of fishing impacts within the expanded sanctuary is not well understood. Discarded anchors have been found on the seafloor, but are not believed to have caused recent impacts, and sanctuary regulations now prohibit anchoring. The number of platform installations declined and the number of platform removals increased in the vicinity of the expansion banks. Research activities had localized impacts, but the benefits of these activities outweigh these impacts.¹

What are the levels of human activities that may adversely influence living resources and how are they changing?

All Sanctuary Areas

Status Description: Some potentially harmful activities exist, but they have not been shown to degrade living resource quality.

Rationale: Low levels of recreational fishing occur in Flower Garden Banks National Marine Sanctuary, and there has been a slight increase in charter fishing effort. There was a decrease in total annual landings for all species in the northern Gulf of Mexico zones that overlap FGBNMS boundaries. Few seismic surveys occurred in the region, with a slight increase since 2009. The number of divers decreased. Marine debris and permitted research occurs, but there is no significant trend. Vessel noise adds to ambient noise in the sanctuary, but impacts are unknown. Experts noted the difficulty in determining impacts to living resources due to the lack of comprehensive data.¹

Water Quality

What is the eutrophic condition of sanctuary waters and how is it changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Eutrophication has not been documented, or does not appear to have the potential to negatively affect ecological integrity.

Rationale: Data collected as part of the Flower Garden Banks National Marine Sanctuary long-term monitoring program suggested that nitrogen, phosphorus, ammonia, and chlorophyll a concentrations in the sanctuary remained below harmful levels for reef ecosystems; however, occasional nutrient spikes occurred. A localized mortality event in 2016 raised concern that increases in offshore flow or coastal waters could bring higher nutrient loads and other stressors to the sanctuary in the future.

Expansion Banks

Status Description: Eutrophication has not been documented, or does not appear to have the potential to negatively affect ecological integrity.

Rationale: In situ data on eutrophication are limited, but available satellite-derived data suggest chlorophyll a concentrations remained at relatively low levels in sanctuary waters. Algal bloom index values were also low.

Do sanctuary waters pose risks to human health and how are they changing?

All Sanctuary Areas

Status Description: Water quality problems have caused measurable human impacts, but effects are localized and not widespread or persistent.

Rationale: Multiple diatom species that are known to cause ciguatera fish poisoning occur naturally in Flower Garden Banks National Marine Sanctuary. While sampling of fish tissue consistently showed elevated levels of ciguatoxins, there have not been any reported cases of ciguatera fish poisoning originating from fish caught in the sanctuary since 2011. Fish tissue sampled from select species within the sanctuary also contained levels of mercury above U.S. Environmental Protection Agency thresholds for limiting consumption.

Have recent, accelerated changes in climate altered water conditions and how are they changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Climate-related changes are suspected and may degrade some attributes of ecological integrity, but have not yet caused measurable degradation.

Rationale: Significantly increasing ocean temperatures (both at the surface and at depth) have resulted in more severe coral bleaching events at Flower Garden Banks National Marine Sanctuary. In addition, pH is decreasing within the sanctuary, making waters more acidic. However, aragonite saturation state and calcification rates have remained high, and conditions within the study period did not cause coral dissolution or erosion.

Expansion Banks

Status Description: Climate-related changes are suspected and may degrade some attributes of ecological integrity, but have not yet caused measurable degradation.

Rationale: Data on climate-related changes within the expansion area of Flower Garden Banks National Marine Sanctuary were limited. Available information showed that sea surface temperatures increased at the expansion banks, while pCO2 increased and pH decreased regionally. Storm activity also occurred in the vicinity of the banks, resulting in periodic increases in river discharge; however, the effects of these discharge events was unknown.¹

Are other stressors, individually or in combination, affecting water quality and how are they changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Selected stressors are suspected and may degrade some attributes of ecological integrity, but have not yet caused measurable degradation.

Rationale: Although more severe storms have resulted in increased river runoff into the Gulf of Mexico region in recent years, persistent changes or trends in salinity, turbidity, or dissolved oxygen have not been detected in Flower Garden Banks National Marine Sanctuary. While a localized mortality event at East Flower Garden Bank in 2016 raised concern that more localized hypoxia events could occur, no additional events of this kind have been documented. ¹

Expansion Banks

Status Description: Resource status is undetermined due to a paucity of relevant information.

Rationale: Although multiple stressors, including more severe storms, have increased river runoff into the Gulf of Mexico region in recent years, changes in salinity and turbidity have not been detected based on satellite-derived data, and no major impacts to the ecological integrity of Flower Garden Banks National Marine Sanctuary are believed to have occurred. However, no long-term in situ data on these parameters were available.

Habitat

What is the integrity of major habitat types and how are they changing?

East Flower Garden Bank, West Flower Garden Bank, Stetson Bank

Status Description: Selected habitat loss or alteration is suspected and may degrade some attributes of ecological integrity, but has not yet caused measurable degradation.

Rationale: Coral cover on the reef cap of East and West Flower Garden Bank remained stable during the study period with small, but significant increases in crustose coralline algae at East Flower Garden Bank and sponge cover at both banks. However, there have been small, but significant, declines in sponge cover within mesophotic habitat at Stetson Bank. Though marine debris was present, it did not appear to degrade habitat.

Expansion Banks

Status Description: Selected habitat loss or alteration is suspected and may degrade some attributes of ecological integrity, but has not yet caused measurable degradation.

Rationale: Based on comparisons to early descriptions of these banks, mesophotic coral densities appeared stable and comparable to those in other regions. The amount of marine debris present did not appear to be increasing significantly, and observed impacts were localized and not measurable at larger scales. Data gathered from recent surveys serve as a baseline for future comparison. Significant data gaps exist, as analyses do not exist for every habitat at every bank.

What are contaminant concentrations in sanctuary habitats and how are they changing?

All Sanctuary Areas

Status Description: Contaminants have not been documented, or do not appear to have the potential to negatively affect ecological integrity.

Rationale: There was no evidence of habitat degradation from contaminants in recent years. Total petroleum hydrocarbon concentrations were undetectable in water samples collected at Flower Garden Banks National Marine Sanctuary following the Deepwater Horizon oil spill in 2010. Barium/calcium ratios in corals sampled within the sanctuary suggested increased barite levels associated with oil and gas production in the Gulf of Mexico; however, this did not appear to affect coral reef habitat.

Living Resources

What is the status of keystone and foundation species and how is it changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: The status of keystone and foundation species appears to reflect near-pristine conditions and may promote ecological integrity (full community development and function).

Rationale: Most foundation species, including corals, sponges, and fishes, were abundant and persistent at East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank. Although the hydrocoral Millepora alcicornis, the sponge Chondrilla nucula, and the long-spined sea urchin Diadema antillarum persisted on the reefs following historic declines, their recovery has been limited. More data are needed on foundation species in mesophotic habitats, and emerging diseases that may affect foundation species also warrant continued monitoring.²

Expansion Banks

Status Description: The status of keystone and foundation species appears to reflect near-pristine conditions and may promote ecological integrity (full community development and function).

Rationale: Baseline data indicated robust populations of foundation coral, sponge, and fish species. However, a lack of long-term data in the expansion area of the sanctuary precluded an assessment of trends.³

What is the status of other focal species and how is it changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Reduced abundances in selected focal species are suspected but have not yet been measured.

Rationale: Populations of focal fish species (including groupers, snappers, and parrotfishes) at East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank have been stable. Manta rays continue to use the sanctuary regularly, with evidence suggesting that individual rays return to these areas after extended periods of time. Lobster populations have remained low in the sanctuary since monitoring began in 2010.⁴

Expansion Banks

Status Description: Resource status is undetermined due to a paucity of relevant information.

Rationale: The few opportunistic observations of whale sharks and manta rays at some banks, as well as limited surveys to quantify fish and crinoids, were insufficient to determine a status or trends for these species in the expansion banks of the sanctuary.

What is the status of non-indigenous species and how is it changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status Description: Non-indigenous species are present and may preclude full community development and function, but have not yet caused measurable degradation.

Rationale: Although non-indigenous species were present at East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank, there was no evidence of associated impacts to ecological integrity. Available data on prey fishes do not suggest there have been declines following lionfish colonization. However, the arrival of new non-indigenous species since the last condition report was concerning.

Expansion Banks

Status Description: Resource status is undetermined due to a paucity of relevant information.

Rationale: Lionfish and orange cup coral have been found in the mesophotic habitats of the 14 banks of the expansion area. Lionfish abundances are increasing, but their impacts on native populations in the expansion banks remain unknown due to a lack of long-term observation data. While orange cup coral was present in isolated areas of the expansion banks, its impact also could not be assessed  due to a lack of time-series data.⁵

What is the status of biodiversity and how is it changing?

East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank

Status: Good (high confidence)

Trend: Not changing (high confidence)

Status Description: Biodiversity appears to reflect near-pristine conditions and promotes ecological integrity (full community development and function).

Rationale: Data on richness, abundance, and cover of fish, coral, and sponge communities indicate thriving and stable assemblages at East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank throughout the reporting period, as well as high genetic connectivity throughout the region.

Expansion Banks

Status Description: Biodiversity appears to reflect near-pristine conditions and promotes ecological integrity (full community development and function).

Rationale: Baseline studies in the expanded portion of the sanctuary indicate high biodiversity among fish, coral, and sponge communities, but limited data prevents assessment of trends. Available data suggest there is high connectivity among sanctuary reefs and banks.

Footnotes

1. A trend rating was not determined by experts during the workshop. On April 24, 2023, FGBNMS and ONMS staff revisited the indicators and datasets and selected an improving trend based on medium evidence and medium agreement, resulting in a medium confidence score.
2. A confidence score was not determined by experts for either the status or trend rating during the workshop. On June 1, 2023, FGBNMS and ONMS staff revisited the workshop notes and determined that there was a robust amount of evidence and a high level of agreement for both ratings, resulting in very high confidence scores.
3. During the expert workshop, a status rating of good/fair was selected; however, a level of agreement among experts was not determined, and therefore a confidence score was not assigned. On June 1, 2023, FGBNMS and ONMS staff revisited the indicators and datasets and determined that a status rating of good was more appropriate. Staff determined a low confidence score for this status rating based on limited evidence and medium agreement. A level of agreement among experts was also not determined for the trend rating during the expert workshop. FGBNMS and ONMS staff revisited the workshop notes and determined high agreement was applicable; when coupled with limited evidence, this resulted in a medium confidence score for the trend rating.
4. A level of agreement and confidence score were not determined by experts during the workshop. On April 24, 2023, FGBNMS and ONMS staff revisited the workshop notes and determined a medium level of agreement, resulting in a medium confidence score.
5. A status rating was not determined by experts during the workshop. On April 24, 2023, FGBNMS and ONMS staff revisited the indicators and datasets and selected an undetermined status based on limited evidence and medium agreement, resulting in a low confidence score. During the expert workshop, a trend rating of worsening was selected; however, staff reevaluated the available information and changed the trend to undetermined, also based on limited evidence and medium agreement, resulting in a low confidence score.