RAPID VULNERABILITY ASSESSMENT FOR 

GRAY’S REEF NATIONAL MARINE 

SANCTUARY

February 2019 | sanctuaries.noaa.gov

NATIONAL MARINE SANCTUARIES CONSERVATION SERIES ONMS-19-01
U.S. Department of Commerce

Wilbur Ross, Secretary

National Oceanic andAtmospheric Administration

RDML Tim Gallaudet, Ph.D., Acting Administrator

National Ocean Service

Nicole LeBoeuf, Assistant Administrator (Acting)

Office of National Marine Sanctuaries

Rebecca Holyoke, Director (Acting)

Report Authors:

Karsten A. Shein1

, Joseph Cavanaugh2, Hélène Scalliet3, 

Sara V. Hutto4, Kimberly Roberson5, B, Shortland5, and 

Lauren Wenzel6

1 National Centers for Environmental Information, Center 

for Coasts, Oceans, and Geophysics

2 National Marine Fisheries Service, Southeast Regional 

Office Protected Resources Division

3 Office of National Marine Sanctuaries

4 Greater Farallones National Marine Sanctuary

5 Gray’s Reef National Marine Sanctuary

6 National Marine Protected Areas Center

Suggested Citation:

Shein, K., J. Cavanaugh, H. Scalliet, S. Hutto, K. Roberson, 

B, Shortland, and L. Wenzel. 2019. Rapid vulnerability 

assessment for Gray’s Reef National Marine Sanctuary.

National Marine Sanctuaries Conservation Series ONMS-19-

01. U.S. Department of Commerce, National Oceanic and 

Atmospheric Administration, Office of National Marine 

Sanctuaries, Silver Spring, MD. 84 pp. 

Cover Photos:

Gray’s Reef National Marine Sanctuary. Credit: Greg 

McFall/NOAA
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About the National Marine Sanctuaries

Conservation Series

The Office of National Marine Sanctuaries, part of the National Oceanic and Atmospheric 

Administration, serves as the trustee for a system of underwater parks encompassing more 

than 620,000 square miles of ocean and Great Lakes waters. The 13 national marine 

sanctuaries and two marine national monuments within the National Marine Sanctuary 

System represent areas of America’s ocean and Great Lakes environment that are of special 

national significance. Within their waters, giant humpback whales breed and calve their 

young, coral colonies flourish, and shipwrecks tell stories of our maritime history. Habitats 

include beautiful coral reefs, lush kelp forests, whale migration corridors, spectacular deepsea canyons, and underwater archaeological sites. These special places also provide homes 

to thousands of unique or endangered species and are important to America’s cultural 

heritage. Sites range in size from less than one square mile to more than 582,000 square 

miles, serve as natural classrooms and cherished recreational spots, and are home to 

valuable commercial industries.

Because of considerable differences in settings, resources, and threats, each marine 

sanctuary has a tailored management plan. Conservation, education, research, monitoring,

and enforcement programs vary accordingly. The integration of these programs is 

fundamental to marine protected area management. The National Marine Sanctuaries 

Conservation Series reflects and supports this integration by providing a forum for 

publication and discussion of the complex issues currently facing the sanctuary system. 

Topics of published reports vary substantially and may include descriptions of educational 

programs, discussions on resource management issues, and results of scientific research 

and monitoring projects. The series facilitates integration of natural sciences, 

socioeconomic and cultural sciences, education, and policy development to accomplish the 

diverse needs of NOAA’s resource protection mandate. All publications are available on 

the Office of National Marine Sanctuaries website (http://www.sanctuaries.noaa.gov).
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Disclaimer

Report content does not necessarily reflect the views and policies of the Office of National 

Marine Sanctuaries or the National Oceanic and Atmospheric Administration, nor does the 

mention of trade names or commercial products constitute endorsement or recommendation 

for use.

Report Availability

Electronic copies of this report may be downloaded from the Office of National Marine 

Sanctuaries website at http://sanctuaries.noaa.gov. 

Contact

Hélène Scalliet

NOAA's Office of National Marine Sanctuaries

Policy and Planning Division

1305 East West Highway

SSMC4 - Room 11351 - n/ORM6

Silver Spring MD 20910

240-533-0648

Helene.Scalliet@noaa.gov
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Table of Contents

Table of Contents...............................................................................................................iii

Abstract.............................................................................................................................. iv

Key Words......................................................................................................................... iv

1. Habitat, Climate, and Climate Change of Gray’s Reef National Marine Sanctuary ...... 1

1.1 Overview of Gray’s Reef National Marine Sanctuary.............................................. 1

1.2 Habitat Characteristics.............................................................................................. 2

1.3 Climate of Gray’s Reef............................................................................................. 2

1.3.1 Environmental Observations.............................................................................. 3

1.3.2 Past and Present Climate.................................................................................... 5

1.3.3 Future Climate Projections .............................................................................. 15

1.4 Potential Climate Impacts....................................................................................... 19

2. Vulnerability Assessment: Methods and Workshop Activities.................................... 21

2.1 Workshop Preparation ............................................................................................ 22

2.2 Overview of the RVA Tool..................................................................................... 24

2.3 GRNMS RVA Workshop ....................................................................................... 26

3. Vulnerability Assessment and Adaptation Planning Results........................................ 28

3.1 Invertebrates/Sessile Macrofauna ........................................................................... 28

3.1.1 Stinking Vase Sponge (Ircinia campana)................................................... 28

3.1.2 Ivory Bush Coral (Oculina arbuscula) ....................................................... 31

3.1.3 Purple-Spined Sea Urchin (Arbacia punctulata)........................................ 35

3.2 Reef Species....................................................................................................... 38

3.2.1 Black Sea Bass (Centropristis striata)........................................................ 38

3.2.2 Tomtate (Haemulon aurolineatum) ............................................................ 42

3.2.3 Northern Red Snapper (Lutjanus campechanus)........................................ 44

3.3 Pelagic Species................................................................................................... 48

3.3.1 King Mackerel (Scomberomorus cavalla).................................................. 48

3.3.2 Round Scad (Decapterus punctatus) .......................................................... 51

................................................................................................................................... 51

3.3.3 Southern Stingray (Dasyatis americana).................................................... 53

3.3.4 Loggerhead Sea Turtle (Caretta caretta) [Northwest Atlantic (NWA) 

Distinct Population Segment (DPS)] ........................................................................ 56

3.3.5 Atlantic Sturgeon (Acipenser oxyrhynchus oxyrhynchus).......................... 60

4. Conclusions and Next Steps.......................................................................................... 66

Literature Cited ................................................................................................................. 72

Acknowledgements........................................................................................................... 78

Glossary of Acronyms ...................................................................................................... 79

Appendix A. Workshop Agenda....................................................................................... 80

Appendix B. Participant List............................................................................................. 83

Appendix C. CEC North American Marine Protected Area Rapid Vulnerability 

Assessment Tool: Worksheets and Instructions ............................................................... 84
iv

Abstract

Gray’s Reef National Marine Sanctuary (GRNMS) is a 22 sq. mile (5700 ha) marine 

protected area approximately 17 nautical miles (31 km) east of the Georgia coast, and is 

part of the National Marine Sanctuary System. It is home to one of the largest “live 

bottom” reef systems in the southeast United States. Gray’s Reef is currently 

experiencing changing environmental conditions, and climate projections to 2100 suggest 

that these changes will continue and likely accelerate. The sensitivity of marine species at

Gray’s Reef to these changes (i.e., vulnerability) and their ability to acclimate to these 

changes (i.e., resilience) will define the sustainability of the sanctuary as a viable marine 

habitat in coming decades.

In November 2017, GRNMS convened an expert workshop to assess the climate 

vulnerability of nine key species that occur within the sanctuary, with participants

identifying two additional species for post-workshop assessments. Participants were 

provided information about the current and projected climate conditions of the sanctuary 

and applied this to their knowledge of each species and its capacity to adapt to changing 

conditions. They used a modified version of the Commission for Environmental 

Cooperation’s North American Marine Protected Area Rapid Vulnerability Assessment 

tool to transform this knowledge into a vulnerability score for each species. Once climate 

vulnerabilities were established, participants discussed possible adaptation strategies 

which, if implemented, might reduce vulnerability.

This report summarizes the outcomes of the Gray’s Reef Rapid Vulnerability Assessment 

workshop. Key findings were that top climate concerns included changes such as storm 

frequency and intensity, increasing water temperature, and ocean acidification. Top nonclimate stressors were identified as well, such as invasive lionfish, sedimentation, coastal 

development, and marine debris/anchor damage. Initial adaptation strategies that 

participants felt could be widely applicable, low cost, and efficacious included lionfish 

reduction efforts (e.g., traps, derbies), and establishing a rapid, post-storm damage 

assessment protocol.

Key Words

Gray’s Reef, climate change, vulnerability, adaptation strategies
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1. Habitat, Climate, and Climate Change of Gray’s Reef 

National Marine Sanctuary

1.1 Overview of Gray’s Reef National Marine Sanctuary

Gray's Reef National Marine Sanctuary (GRNMS) off the coast of Georgia is one of the 

largest near-shore "live-bottom" reefs of the southeastern United States. It is just one of 

14 (with two more in designation at present time) marine protected areas that make up the 

National Marine Sanctuary System and is governed by the National Marine Sanctuaries 

Act.

The approximately 22 square mile (about 14,000 acres or 5700 ha) marine protected area 

is situated roughly 17 nautical miles (31.5 km) east-southeast of Sapelo Island, Georgia

(Fig. 1.1). GRNMS is currently the only protected natural reef area on the continental 

shelf off the Georgia coast and one of only a few natural marine protected areas in the 

ocean between Cape Hatteras, North Carolina and Cape Canaveral, Florida. Gray's Reef 

is just a small part of the U.S. territorial Atlantic Ocean, yet its value as a natural marine 

habitat is recognized nationally and internationally.

"Live bottom" is a term used to refer to hard or rocky seafloor that typically supports high 

numbers of large invertebrates such as sponges, corals, and sea squirts. These spineless 

creatures thrive in rocky areas, as many are able to attach themselves more firmly to the 

hard substrate, as compared to sandy or muddy "soft" bottom habitats. Within GRNMS 

Figure 1.1 Location and spatial extent of GRNMS off the Georgia coast. (Image: NOAA)
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there are rocky ledges with sponge and coral live bottom communities, as well as sandy 

bottom areas that are more typical of the seafloor off the southeastern U.S. coast.

1.2 Habitat Characteristics

Gray's Reef is a submerged hard bottom (carbonate-cemented sandstone) area that, as 

compared to surrounding areas, contains extensive but scattered rock outcroppings. The 

rocky ledges can be as tall as six feet and lie under 60 to 70 feet of ocean water. The 

rocky ledges are complex: they have nooks, crannies and bumps, and plenty of places for 

invertebrates to latch on to and for fish to hide in. Some of the rocky ledges are large 

enough to accommodate resting sea turtles. The rocky places provide a firm base for a 

variety of invertebrates that live their lives permanently attached to the rock. These 

animals include bryozoans (moss fauna), ascidians or tunicates (sea squirts), sponges, 

barnacles, and hard-tubed worms. The complex structure provides shelter for mobile 

invertebrates such as worms, shrimps, and crabs. Many fish shelter in the reef or hover in 

the water column above.

Algae (marine plants) and invertebrates grow on the exposed rock surfaces. Dominant 

invertebrates include sponges, barnacles, fan corals and other soft corals, hard corals, sea 

stars, crabs, lobsters, snails, and shrimps. The reef attracts numerous species of fish that 

live on or near the substrate (benthic) or that swim in the water above (pelagic). These 

include black sea bass, snappers, groupers, and mackerels. Since Gray's Reef lies in a 

transition area between temperate and tropical waters, fish population composition 

changes seasonally. Loggerhead sea turtles, a threatened species, use Gray's Reef yearround for foraging and resting and the reef is near the only known winter calving ground 

for the highly endangered North Atlantic right whale.

Gray's Reef is a consolidation of marine and terrestrial sediments (sand, shell, and mud) 

which was laid down as loose aggregate between six and two million years ago. Some of 

these sediments were deposited by coastal rivers draining into the Atlantic and others 

were brought in by currents from other areas (Harding and Henry 1990). These sediments 

accumulated until a dramatic change began to take place on Earth during the Pleistocene 

Epoch, between 1.8 million and 10,000 years ago. It was during this time that the area 

which is now Gray's Reef was, at times, exposed land and the shoreline was as much as 

80 miles east of its present location. As a result of this exposure, the sediments solidified 

into porous carbonate-cemented sandstone rock. As the glacial ice melted, the water 

returned to the sea, filling the ocean basins back to their earlier levels.

1.3 Climate of Gray’s Reef

The climate of GRNMS is characterized by both atmospheric and oceanographic 

components. Chief among them are air and water temperature, precipitation, currents, 

salinity, pH (acidity), winds, waves, and storms. The region sees a warm summer and 

cool winter, with a summertime precipitation maximum and late fall minimum. Although 
3

climate classifications are not generally assigned to offshore geographies, based on the 

criteria defined by the Köppen-Geiger climate classification system (Köppen 1918; 

Geiger 1961), the region in which Gray’s Reef resides is considered humid subtropical 

(Cfa). This means that the coldest month averages 0°C (32°F), at least one month’s 

average temperature exceeds 22°C (71.6°F), and no fewer than four months average 

above 10°C (50°F). In Cfa climates there is no significant precipitation difference 

between seasons.

Like the atmosphere, the water temperature also experiences significant seasonality. The 

sanctuary sits on the continental shelf at a depth of between 18 and 21 meters (60 to 70 

feet). As such, the sanctuary is entirely within the mixed surface layer of the ocean and is 

influenced by diurnal and seasonal heating cycles, tidal currents, and both tropical and 

extratropical storm systems. Gray’s Reef sits inshore of the major ocean current in the 

region, the Florida Current/Gulf Stream, but is occasionally affected by eddies that shear 

from the main current channel. The Labrador Current also extends into the region 

periodically (inshore of the Florida Current), transporting colder, denser water. While 

longshore currents tend to be less prevalent than tidal processes in the coastal zone (Dean 

and Walton 1973; Watson 1980), there is a weak and ephemeral longshore component 

that produces a net southward sediment transport, but with frequent reversals (Wang et al. 

1998). In one or two locations along the coast, the transport is predominantly northerly 

(e.g., Cumberland Island, Georgia, Griffin and Henry 1984; Tybee Island, Oertel et al. 

1985).

1.3.1 Environmental Observations

Given the importance of weather to seafaring, atmospheric and oceanographic data 

collection has taken place in the region since the 1700s, when passing vessels (primarily 

those of the British Navy) would record environmental observations (e.g., air 

temperature, sea surface temperature, winds, sky condition, general character of the 

weather). In many cases, these data have been transcribed from historical ships’ logs and 

included in the International Comprehensive Ocean-Atmosphere Data Set (ICOADS; 

Freeman 2017). These historical data, averaged over 2°x2° grid boxes (1°x1° since 1960) 

provide for monthly average water temperature (among other parameters) in the region 

dating back to 1824.

NOAA’s National Data Buoy Center (NDBC) operates a moored buoy (41008) within the 

GRNMS boundary. It is a 3-meter discus buoy with the Advanced Modular Payload 

System (AMPS), which is the latest NDBC payload and incorporates sensors that satisfy 

the growing need for climatological information (NDBC 2009). Buoy 41008 observes the 

variables listed in Table 1.1 on an hourly basis, and has done so since 1988, with a gap in 

observations from 1992 to 1997.
4

The NDBC buoy also serves as the framework for a series of additional instruments 

installed by academic researchers as part of the Ocean Acidification Data Stewardship 

(OADS) project (Jiang et al. 2016). These instruments, installed by researchers from the 

University of Georgia, monitor elements such as pH, partial pressure of CO2, dissolved 

oxygen, and seabed temperature (Sabine et al. 2011). Observations from this suite of 

instruments extend from 2006 to the present.

Sea level is monitored by tide gauges located along the Atlantic coast, including the 

nearest at Ft. Pulaski, and another at Fernandina Beach, Florida

(tidesandcurrents.noaa.gov). The gauge at Ft. Pulaski has a record of water level 

extending back to 1935, and the one at Fernandina Beach extends to 1897. Both are part 

of the National Water Level Observing Network (NWLON) and are instrumental in 

evaluating the change in water level along the Georgia coast over that time period.

Satellite observations of sea surface temperature (SST), altimetry, cloud cover, outgoing 

longwave radiation, and ocean color (e.g., chlorophyll concentration), and other 

parameters are incorporated into several datasets available to the public. In many cases 

these satellite datasets extend back in time at least 30 years and are available at 

resolutions finer than five kilometers. A number of these satellite observation datasets 

relevant to Gray’s Reef are available as Climate Data Records (e.g., Banzon et al 2016) 

from the National Centers for Environmental Information (NCEI; www.ncei.noaa.gov). 

Two U.S. National Weather Service Doppler radars (WSR-88D) positioned at 

Jacksonville, Florida and Charleston, South Carolina provide continuous monitoring of 

hydrometeorological (e.g., rain, snow) and to some extent winds over Gray’s Reef, and 

have been doing so since their installation in the 1990s (though non-Doppler [WSR-57 

and WSR-74] radars have existed at these locations since the 1950s). Observations from 

these radars are archived by and accessible from NCEI (Ansari et al. 2017).

Lastly, a number of research activities within and around the GRNMS have produced a 

suite of ad hoc data sets of a variety of environmental variables (e.g., Watson 1980; 

Hyland et al. 2001; Hare et al. 2003; Balthis et al. 2007). However, in general such data 

sets are of insufficient length to reconcile changes in climate over time.

Table 1.1. NDBC buoy 41008 measured variables.

Wind direction Dominant Wave Period Atmospheric Pressure Water Temperature

Wind speed Average Period Pressure Tendency Dew Point

Wind Gust Mean Wave Direction Air Temperature Heat Index

Wave height Source: National Data Buoy Center (NDBC 2009)
5

1.3.2 Past and Present Climate

Geologic evidence suggests that the substrate of Gray’s Reef formed during the 

Pleistocene Epoch (Harding and Henry 1990; Garrison et al. 2016). During the 

Pleistocene Epoch (~2.59 million to 11,700 years ago) the climate was characterized by 

several major ice ages, which oscillated between glacial and interglacial periods. As a 

result, sea level fluctuated dramatically, falling as glacial ice expanded and rising as the 

glaciers melted (Hansen et al. 2013). At times, Gray's Reef was dry land, with the 

shoreline as much as 80 miles east of where it is today. 

Analyses by Hansen et al. (2013) suggest that the prehistoric period since the formation 

of Gray’s Reef has been one of substantial variability in both temperature and sea level. 

Average sea level between 2 million and 10,000 years ago was generally below that of 

today, falling to between 50-120 meters below present sea level during glacial periods 

(Fig. 1.2). Globally averaged surface temperature during the Pleistocene was 

approximately 2-3°C cooler than at present, with annual fluctuations ranging from 0°C to 

approximately 6°C cooler than the 2016 global average temperature (Fig. 1.3).

Figure 1.2. Global mean sea level reconstructions based on paleoclimate proxy 

data. Figure from Hansen et al. (2013).
6

Since the mid-1800s, globally averaged surface air temperature has been on an upward 

trajectory (Fig. 1.4), rising at a rate of 0.07°C per decade, resulting in an overall increase 

of 0.94°C between 1880 and 2016 (Blunden and Arndt 2017). This increase in surface 

temperature is joined by a corresponding but delayed increase in sea surface temperature 

(SST; Fig. 1.5). Monthly averaged data from NOAA suggest that, after initially 

continuing to cool, modern-era SST began to increase around 1908 at a rate of 0.08°C per 

decade for a 1909-2016 increase of 0.92°C.

While globally- and annually-averaged data are useful for understanding large-scale 

trends in variables of interest, they mask local and regional scale variability that can be 

critical to addressing issues of species or habitat vulnerability. These local to regional 

scale variables include air and water temperature, water chemistry, storm conditions, and 

currents.

Figure 1.3. Global surface temperature reconstructions (blue) and moving averages 

(red) based on paleoclimate proxy data by Hansen et al (2013).
7

Air and water temperature

Based on monthly averaged air and sea surface temperatures obtained for the ICOADS

grid box enclosing GRNMS, the sanctuary experiences hot summers and mild to cool 

winters (Table 1.2).

Figure 1.4. Globally averaged annual surface air temperature anomaly 1880-2016 

(from Blunden and Arndt 2017). Anomalies are based on the 1901-2000 average.

Figure 1.5. Globally averaged monthly SST 1880-2016 from NOAA. Anomalies are based 

on the 1971-2000 average. (Image: NOAA)
8

Using these data obtained from ICOADS for the region surrounding GRNMS, and 

integrating in situ buoy data from the sanctuary since 1988, annually averaged SST has 

increased since 1824 by 1.15°C (0.006°C/yr), and in 2016 averaged 22.30°C. Annual 

average air temperature has similarly increased by 1.20°C (0.0072°C/yr) since 1849, with 

a 2016 average of 21.16°C.

Large-scale weather patterns

The region is subjected to the occasional intrusion of strong cold fronts that push offshore 

from the continent and may raise significant swells from the west and northwest ahead of 

and during passage. These fronts are most pronounced from late fall through early spring 

and are frequently associated with developing “Nor’easters” (extratropical cyclones) that 

form along the Gulf Coast or in the vicinity of the sanctuary itself. Wintertime cold fronts 

may drop air temperatures to below freezing for several days and allow for substantial but 

temporary chilling of the ocean’s surface layer. The surface low driving these fronts may 

also pass over the region, dropping the central pressure and creating gale conditions. The 

so-called “Storm of the Century” in March 1993 was one example of this (Fig. 1.6).

Table 1.2. Monthly and annual sea surface (1824 -2016) and air temperature (1849 - 2016) observed in 

the vicinity of GRNMS. (Source: ICOADS)

Temp. 

(°C) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann

SST 

Min

8.0 6.9 7.5 15.6 18.3 21.2 24.4 25.6 24.2 20.0 14.7 9.8 11.1

SST 

Mean

14.9 14.5 16.3 19.3 23.0 26.1 27.9 28.3 27.3 24.3 20.4 17.0 21.2

SST

Max

24.2 24.4 26.7 26.7 29.0 29.8 30.8 31.4 30.5 30.6 26.7 24.7 27.9

Air 

Min

1.4 0.0 1.9 12.6 18.2 22.5 21.2 22.2 22.0 14.4 11.2 4.0 6.7

Air 

Mean

12.7 13.2 15.6 19.5 22.9 26.0 27.4 27.3 26.1 22.5 18.0 14.5 20.4

Air 

Max

23.0 22.3 25.6 24.9 29.0 33.3 31.1 30.4 30.0 28.5 25.1 25.0 28.9
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Both the position and strength of the Bermuda High, especially during the summer 

months, will have a significant effect on the day-to-day weather, and thus the seasonal 

climate at GRNMS (Fig. 1.7). The proximity of the high produces an average annual sea 

level pressure at Gray’s Reef of 1018.0 hPa, approximately 5 hPa greater than the global 

mean sea level pressure of 1013.25 hPa. The clockwise rotation of the high, which is, on 

average, centered east of GRNMS, produces a predominant inflow of warm and humid 

air into the region from the east. This high also influences the steering of tropical 

cyclones in the vicinity. A strong, inshore extent of the high will inhibit tropical system 

impacts to the sanctuary, while a weaker or more offshore high may direct storms over 

the region.

Tropical cyclones

Tropical cyclones impact 

Gray’s Reef and 

surrounding waters from 

time to time. The 

International Best Track 

Archive for Climate 

Stewardship (IBTrACS; 

Knapp et al. 2010) 

identifies 47 tropical 

cyclone systems that have 

passed within 25 NM of 

the sanctuary since 1853, 

including three in 2016 

Figure 1.6. Surface weather maps showing (L) the March 1993 “Storm of the Century,” and (R) a typical 

cold front that pushed past GRNMS and out to sea. (Source: NOAA)

Figure 1.7. Idealized representation of the pressure and wind 

patterns associated with the Bermuda High (not to scale). Clockwise 

airflow advects warm air over GNRMS and higher pressure can 

steer hurricanes toward the area. (Image: Karsten Shein/NOAA).
10

(Fig. 1.8). Given the relatively 

shallow depth of the sanctuary, 

conditions associated with strong 

storm systems may damage the 

sanctuary habitat.

Ocean currents

A major factor in the ocean climate 

of Gray’s Reef is its proximity to 

the Florida Current (Fig. 1.9). This 

current moves north-northeast 

along the U.S. coast from southern 

Florida, eventually becoming the 

Gulf Stream. The current has a 

mean transport of around 31 

Sverdrup (Sv)1

, but is far higher 

and more variable at the sanctuary 

latitude (perhaps as much as 50 Sv; 

e.g., Leaman et al. 1989). There is a 

strong seasonal component to the transport, and its position relative to the sanctuary can 

greatly affect temperature, current, and nutrient loading. The current also often sheds 

eddies anywhere from tens to hundreds of kilometers in diameter, and can affect the 

sanctuary even though the main current channel may be some distance away.

In addition to the Florida Current and Gulf Stream transporting warmer water northward, 

the Labrador Current transports cooler water equatorward along the coast, inshore of the 

Gulf Stream. The Labrador Current generally crosses southeasterly beneath the Gulf 

Stream at around Cape Hatteras, North Carolina (Richardson 1977), but may on occasion 

influence inshore waters south of the cape (Talley and McCartney 1982).

Ocean Chemistry

Ocean chemistry can play an important role in the health of the GRNMS ecosystem. The 

ocean is a major sink for atmospheric carbon dioxide (CO2), and changes in the quantity 

of dissolved CO2 in ocean water alter the pH of the water and affect the availability of 

carbonates upon which many marine organisms rely for shell and skeletal growth. Global, 

annually averaged partial pressure of CO2 in the atmosphere in 2016 was 404.21 μAtm 

(404.21 parts per million [ppm]) and, measured since 1959, has been increasing at an 

average rate of +1.55 ppm/yr, increasing to a rate of +2.43 ppm since 2010 (Fig. 1.10).

 1 http://oceancurrents.rsmas.miami.edu/atlantic/florida.html

Figure 1.8. Tracks of known tropical storm and hurricanes 

that have passed within 25 nautical miles of Gray’s Reef, 

1853-2016. (source: https://coast.noaa.gov/hurricanes/).
11

Figure 1.10. Annual mean growth rate of CO2 at Mauna Loa Observatory. Black lines are decadal 

averages. (Image: NOAA)

Figure 1.9. MODIS SST from NOAA-18 satellite on March 21, 2017, showing the position of the Florida

Current/Gulf Stream just east of Gray’s Reef (yellow square, not to scale). Heat transport of the current 

is substantial, as is the rate of flow. Cooler conditions prevail inshore, partly due to transport of Labrador 

sea water around Cape Hatteras. (Image: Rutgers University Department of Marine and Coastal 

Sciences)
12

Measurements of atmospheric pCO2 levels at the GRNMS data buoy closely mirror the 

global average, with a 2006 level around 380 ppm, rising to a 2016 level of around 400 

ppm (Fig. 1.11). More critical to the underwater habitat of GRNMS is the dissolution of 

CO2 into the water column.

As a sink for CO2, the ocean accounts for the uptake and storage of roughly 26 percent of 

the CO2 that has been released by anthropogenic activities (Le Quéré et al. 2012). 

However, the continued absorption of CO2 by the ocean also reduces the available 

capacity to continue absorbing CO2 at those rates (the Revelle factor), while increases in 

water temperature have the opposite effect (Sabine et al. 2004). Globally, average 

seawater pH has seen a decrease of around 0.11 to 8.08 since preindustrial times (PMEL 

2017). Observations at GRNMS between 2006 and 2014 reveal that ocean pCO2 levels 

have a pronounced seasonal signal (Fig. 1.11), ranging between around 250 ppm in 

summer and over 600 ppm in winter. The trend between 2006 (~370 ppm) and 2013 

(~450 ppm) was around +10 ppm/yr.

Precipitation and river discharge

Lastly, an important climatological consideration for Gray’s Reef is precipitation, 

especially terrestrial precipitation between the Georgia coast and inland to the 

Appalachian foothills. The amount and timing of precipitation falling here affects the 

discharge of the Altamaha and other rivers. High discharge/flow will reduce surface 

salinity levels in the region, may temporarily reduce water temperature at GRNMS, and 

Figure 1.11. Partial pressure of CO2 (ppm) for air and seawater, measured at GRNMS between 2006 

and 2014. (Image: Scott Noakes/University of Georgia)
13

can inhibit upwelling from the 

shelf edge to the east. The 

timing of droughts and rainfall 

may also affect sediment and 

nutrient discharge onto the reef 

from land-based sources.

Precipitation is measured at 

several coastal locations, 

including the nearest observing 

station at Sapelo Island, GA. 

Daily precipitation totals, 

available from Sapelo Island 

since 1957, suggest that there is a summer (Aug-Sep) peak, with a September average 

total of 6.88 in (175 mm), and a minimum of 2.27 in (58 mm) in November (Fig 1.12). 

Annual total precipitation has been declining at a rate of -0.0892 inches/year, or -5.26 in 

over the 1957-2017 period of record (Fig 1.13).

Global climate projections suggest that precipitation in many locations will become more 

variable and experience more frequent extreme events. Data from Sapelo Island 

demonstrate that the number of days per year in which 1.0 inch (25 mm) of precipitation 

was observed has increased at a rate of 0.0619 days/yr (3.65 days over the period of 

record; Fig. 1.14). Simultaneously, the number of multi-day periods (or runs) of days 

where no precipitation fell showed only a slight decline of -0.0065 runs/yr (Fig 1.14).

One potential driver of precipitation over Gray’s Reef is the North Atlantic Oscillation 

(NAO). This teleconnection is defined by the pressure difference between the Icelandic 

Low and the Azores High (Fig. 1.15). Not only does the NAO control the strength and 

pattern of westerly atmospheric flow across the North Atlantic, but associated storm 

events as well, 

especially in winter

(Fig. 1.16). The 

positive phase of the 

NAO that has been 

in place for much of 

the past 40 years is 

partly associated 

with warming water 

temperatures and 

increased rainfall 

along the U.S. East 

Coast (Hurrell and 

Deser 2010).

Figure 1.12. Monthly average total precipitation observed at 

Sapelo Island, GA between 1957 and 2017. (Image: xmacis).

Figure 1.13. Annual total precipitation observed at Sapelo Island, GA, 1958-

2017. Blue dotted line is a linear trend applied to the data. (Source: xmacis)
14

Figure 1.15. NAO Index since 1864. (Source: National Center for Atmospheric Research)

Figure 1.14. Number of days of heavy (≥1.0 in.) precipitation (solid purple line), number of multi-day 

periods of zero precipitation (dashed green line), and associated linear trend lines (dotted similar color) 

observed at Sapelo Island, Georgia. (Source: xmacis)
15

1.3.3 Future Climate Projections

Data in this section are derived from several sources as indicated but come primarily 

from the Coupled Model Intercomparison Project Phase 5 (CMIP5), a suite of 

approximately 62 coupled ocean-atmosphere climate models (Taylor et al. 2012). CMIP5 

is an ensemble of climate models that together produce a suite of possible future climates 

when run under several different assumptions about greenhouse gas concentrations in the 

atmosphere and their resulting radiative influence. CMIP5 data are used by the 

Intergovernmental Panel for Climate Change (IPCC) in their 5th Assessment Report on 

Climate Change (IPCC 2013), from which this section draws heavily. Though these 

assessments have focused almost entirely on terrestrial climate change (with the 

exception of sea level rise), the climate models on which these reports are based have in 

most cases included coverage of the ocean. Additional sources of relevant climate change 

information are the Fourth U.S. National Climate Assessment (USGCRP 2017) and, for 

the Southeast U.S., the NOAA NESDIS Tech Report 142-2 “Climate of the Southeast 

U.S.” (Kunkel et al. 2013).

Figure 1.16. Northern Hemisphere weather patterns consistent with the positive and negative phases of 

the North Atlantic Oscillation teleconnection. (Image: NOAA) 
16

Sea surface temperature

Of importance to Gray’s Reef is sea surface temperature (SST). The CMIP5 models use 

several Relative Concentration Pathways (RCPs): RCP 2.6 (low emissions scenario), 

RCP4.5, RCP6, and RCP8.5 (high emissions scenario). The numbers represent the 

change in radiative forcing (Wm-2) of the atmosphere by 2100 AD, relative to 

preindustrial conditions.

For Gray’s Reef, the RCP2.6 (low emissions) outlook is for an increase in SST of 0.8°C 

(relative to the 1981-2010 average) by 2050, with a leveling off thereafter, through 2100. 

Alternatively, RCP8.5 suggests a steady increase in SST through 2100, reaching 1.4°C 

above the 1981-2010 average by 2050 and over 3°C by 2100 (Fig. 1.17).

Sea level change

Sea Level along the coast of Georgia is expected to rise between 152 mm (6 in) and 330 

mm (13 in) within the next 50 years, and between 0.5 to 1.2 m (20 to 39 in) by 2100 (e.g., 

IPCC 2013; Keating and Habeeb 2012; Climate Central 2012; cf. 

http://gacoast.uga.edu/research/major-projects/sea-level-rise/). Significance for the 

Figure 1.17. Annual average SST anomalies (1981-2010 mean) for GRNMS through 2100 derived from 

the four relative concentration pathways (RCPs) of the CMIP5 ensemble. (Source: KNMI; 

http://climexp.knmi.nl/)
17

Gray’s Reef ecosystem is that rising sea levels support more frequent and extensive 

coastal inundation, especially when tides and periodic storm surges are factored in. The 

result of inundation events is the potential to mobilize significant quantities of terrestrial 

sediments and pollutants that were deposited on the land prior to inundation. Drainage 

from such events has the potential to transport these pollutants to Gray’s Reef. This 

situation may be exacerbated as well should rising sea levels and other factors, both 

climatic and non-climatic, reduce the extent and effectiveness of living shorelines (i.e., 

salt marshes and wetlands).

Pressure patterns and tropical cyclones

In addition, research is suggesting that the position of the center of the Bermuda High is 

gradually expanding westward and intensifying under warmer climates (Li et al. 2012). A 

summary of this research can be found at http://www.climatecentral.org/news/globalwarming-may-shift-summer-weather-patterns-study-finds-15100. Additionally, the 

poleward expansion of the Hadley Cell, the planetary circulation pattern governing 

atmospheric flow in the tropics, as well as the increasing size of the cold pool of water in 

the North Atlantic due to glacial melt from the arctic and Greenland, may result in a net 

north to northeast shift of the high’s center. As it migrates, the high will no longer 

regulate conditions at Gray’s Reef as significantly as it has in the past.

The shift in the Bermuda High also affects the steering of North Atlantic tropical 

cyclones. Though they do not indicate an increase in the frequency of tropical cyclones, 

IPCC future climate scenarios suggest those storms are likely to increase in intensity by 

between 2 and 11 percent by 2100, and in that same time period the number of “very 

intense” storms (Category 4 or 5) is expected to increase by an even larger percentage (90

percent). A summary of these findings (with references) are at 

https://www.gfdl.noaa.gov/global-warming-and-hurricanes/.

Ocean acidification

All future climate scenarios are run under an assumption of a continued increase, to some 

degree, in atmospheric CO2 and other greenhouse gases. Such an increase will likely 

continue to produce a corresponding increase in the quantity of dissolved CO2 taken up 

by the ocean, and therefore a corresponding decrease in pH. Atmospheric CO2 is 

expected to reach levels near 800 ppm by 2100 (IPCC 2013), and seawater pH is 

expected to decrease an additional 0.1 during that period, to around 7.8 (Fig. 1.18; Feely 

et al 2009). 

This decrease is expected to result in aragonite undersaturation throughout the global 

ocean, beginning in the Arctic by 2020 and gradually extending to the area of GRNMS. 

Aragonite is an important form of calcium carbonate (CaCO3) and occurs naturally in 
18

many marine animal shells and coral skeletons. A saturated state for aragonite supports 

shell and skeletal growth among these animals. Undersaturation can promote difficulty in 

uptake and even dissolution of those calcareous frameworks. Feely et al. (2009) estimate 

a 21 to 40 percent decrease in aragonite saturation for GRNMS by 2100. The Labrador 

Current may also accelerate this process by directly transporting undersaturated water to 

the region from the Arctic.

Other changes

Numerical models of the ocean suggest that between now and 2050, GRNMS should 

expect a decrease in transport rates of the Florida current as well as a shift in the median 

track of the Gulf Stream. Additionally, atmospheric warming has been connected to the

intensity and extent of the Bermuda High (Li et al. 2010; Li et al. 2012). Future climate 

scenarios suggest that between now and 2050, the Bermuda High will continue to 

strengthen and expand. This is likely to increase the frequency and severity of droughts 

over the Southeast. Coupled with the expected increase in the occurrence of extreme 

rainfall events, this change increases the likelihood of increased sediment/nutrient 

discharge and mobilization events for GRNMS. 

Changes in the Bermuda High are also likely to influence the strength and extent of the 

subtropical oceanic gyre that rests beneath it and may also play a role in the expected 

decrease in transport rates of the Florida Current. Similarly, an increase in the extent of 

the gyre is likely to push both the Gulf Stream and southern extent of the Labrador 

Current northward, reducing the likelihood of cool water intrusions into the GRNMS.

Dissolved oxygen has been steadily declining in the global ocean, and is expected to 

continue that decline, by between 1 and 7 percent by 2100 (Schmidtko et al. 2017). At 

Figure 1.18. Historical and projected seawater pH for the world ocean. (Image: Feely et al. 2009)
19

GRNMS, dissolved oxygen may decline by around 0.004 mol m-3 (1%) by 2050. 

However, this decline may be enhanced by a combination of increased water temperature 

and a greater concentration of nutrient/sediment levels resulting from more erratic and 

intense river discharge along the Georgia coast.

Other long-term changes in the characteristics of the Atlantic Ocean, such as the Atlantic 

Thermohaline Circulation and the Atlantic Multidecadal Oscillation (AMO) are receiving 

attention but remain poorly understood.

1.4 Potential Climate Impacts

All ecological systems are to some degree or another adapted to and influenced by the 

environmental conditions to which they are exposed. A variable and changing climate has 

the potential to expose species and habitats to conditions outside their evolutionary 

tolerance, resulting in adverse responses, such as increased stress and morbidity, forced 

migration, lowered fecundity, competition from invasive species, susceptibility to 

pathogens, and even behavioral stress and physical injury. Mobile species may or may 

not alter their range to take advantage of changing conditions, as has been seen in the 

general poleward migration of a variety of fish populations (e.g., Nye et al. 2009; Mills et 

al. 2013), but often they either do not find support from a suitable habitat during forced 

migrations or are out-competed by native species. Even when mobile species are able to 

migrate quickly in response to climate stressors, their migration may not synchronize 

with prey species that also may be migrating in response to the same climate-induced 

pressures. Sessile species, on the other hand, are more limited in their ability to mobilize 

in response to threats because their life histories are dependent on larval stages (both 

motile and sessile) to shift their distribution. Therefore, sessile species often must quickly 

adapt to changing environmental conditions or suffer widespread mortality (e.g., HoeghGuldberg et al. 2007; Sorte et al. 2011). The accelerated time frame of climate stressors 

may exceed the resiliency of many mobile and sessile species to adapt quickly enough to 

successfully relocate (mobile species) or survive where they currently exist (sessile 

species). Migratory/range shifts for species in response to climate-induced stressors can 

also cause complex non-linear changes in biotic interactions between species leading to 

trophic cascades.

Presented with a summary of potential changes in climate (atmospheric and 

oceanographic) conditions that may affect GRNMS, and the list of species for which this 

rapid vulnerability assessment was to be conducted (RVA species), workshop 

participants identified a few primary changes that likely pose the greatest challenges to 

those species’ health and vitality over the next 50-year time frame. The climate changes 

of greatest concern were changes in the characteristics (e.g., frequency, intensity, track) 

of severe tropical (and in some cases extratropical) cyclones, increase in water 

temperature, ocean acidification, changes in currents, changes in precipitation patterns 

over sediment/nutrient contributing river basins, turbidity, diminished dissolved oxygen, 

and changes in upwelling/mixing. Nearly all RVA species appear likely to be affected by 
20

changes in storms and increasing water temperature by 2050, although these factors also 

play a role in modifying other climate change stressors, such as increased turbidity and 

decreasing seawater pH.

Some potential effects of warming seawater in GRNMS include the northward shift of 

species range and disruption of reproductive cycles. Impacts from stronger tropical and 

extratropical cyclones are led by potential physical damage to the GRNMS habitat as 

well as scouring/smothering of sessile species and food sources. Additionally, warming 

water and increased nutrients may produce more frequent and long-lasting hypoxic 

events and harmful algae blooms in the region. It is uncertain to what extent such events 

would affect GRNMS directly.
21

2. Vulnerability Assessment: Methods and 

Workshop Activities

In November 2017, GRNMS and the National Marine Protected Areas Center convened a 

rapid vulnerability workshop at the GRNMS offices adjacent to the University of Georgia 

Skidaway Institute for Oceanography (SkIO) on Skidaway Island, Georgia. The 

workshop tasked an invited group of topical experts (see Appendix B) with the objective

of summarizing exposure and response of nine keystone marine species to projected 

changes in environmental conditions at GRNMS and standardize those summaries using 

the North American Marine Protected Area Rapid Vulnerability Assessment Tool2 (Fig. 

2.1), developed by the Commission for Environmental Cooperation (CEC 2017; see 

Appendix C). The nine species assessed were initially identified by GRNMS staff. 

Workshop participants subsequently modified that list (as described further on) and

suggested adding two species via post-workshop assessments (following the same 

protocols). 

 2

www3.cec.org/islandora/en/item/11739-north-american-marine-protected-area-rapid-vulnerabilityassessment-tool

Figure 2.1. North American Marine Protected Area Rapid Vulnerability Assessment Tool from the 

Commission for Environmental Cooperation (CEC). Image: Commission for Environmental Cooperation
22

2.1 Workshop Preparation

The most critical component of a vulnerability assessment is ensuring that the needed 

expertise and partnerships will be represented by the right combination of participants. 

Months in advance of the workshop, sanctuary staff and organizers identified individuals 

with expertise regarding (1) biological and ecological information specific to the species 

of interest, (2) regional climate science, and/or (3) management, partnerships, and 

implementation. It was important to include representation from all levels of government 

(federal, state, local), academic institutions, and non-governmental organizations to 

ensure a well-balanced perspective throughout the assessment.

Given that this effort is considered a “rapid” vulnerability assessment, the workshop was 

time limited (1.5 days) and much of the participant orientation took place in advance of 

the workshop opening. The project team compiled and distributed the following materials 

to participants to ensure they would be well-informed with consistent data and trends, 

methodology, and expectations for the workshop:

● Instructions for use of the RVA tool.

● Read-ahead document that presented climate trends and data, species data, and 

geographical overview.

● Collection of literature to support the assessment.

Confirmed participants (Appendix B) were asked to join in a pre-workshop webinar in 

which organizers briefed them on workshop logistics (see Appendix A) and how to apply 

the RVA Tool (Appendix C), and provided a chance for the participants to have their 

questions regarding the workshop or read ahead materials addressed. This webinar 

proved valuable both to organizers and participants, and helped the workshop to run more 

quickly and smoothly.

The RVA tool used in the GRNMS workshop produces a metric for habitat vulnerability 

to climate change. However, given the small size and complex nature of the GRNMS 

habitat, sanctuary staff concluded it would be more effective to focus the assessment on 

individual species occupying the habitat. Originally, twelve species were selected by 

GRNMS staff, but workshop time limitations and a discussion among participants during 

preliminary phases of the workshop regarding availability of information for certain 

species (e.g., Caribbean lancelet, fan coral) modified the list of species to nine in four

niche groups, with two additional species selected for post-workshop assessment (Table 

2.1).
23

Fortunately, although the RVA tool was developed for habitat assessment, with a few 

critical modifications to the worksheets, the tool can be adapted to other resources of 

interest, including species. One of the authors of this report was also a developer of the 

CEC RVA tool that was adapted for use by GRNMS, and facilitated the use of the tool in 

the workshop. She also consulted with the other tool developer (EcoAdapt) to ensure the 

protocol was appropriately adapted for assessing species vulnerability rather than habitat.

Following consultation with the tool developers, the worksheets were modified as 

follows:

Step 1

● Box 1: Habitat list replaced with list of species (identified in Table 2.1 above)

Steps 2 & 3

Table 2.1 List of species selected for rapid vulnerability assessment.

Species Common Name Niche Group

Ircinia campana

(Lamarck 1816) Stinking vase sponge Sessile Macrofauna

Oculina arbuscula

(Agassiz, 1864) Ivory bush coral Sessile Macrofauna

Arbacia punctulata

(Lamarck 1816) Atlantic purple sea urchin Sessile Macrofauna

Centropristis striata

(Linnaeus 1758) Black sea bass Reef-Associated Predator

Haemulon aurolineatum

(Cuvier 1830) Tomtate Reef-Associated Predator

Lutjanus campechanus 

(Poey 1860) Red snapper Reef-Associated Predator

Scomberomorus cavalla

(Cuvier 1829) King mackerel Migratory Pelagic Predator

Decapterus punctatus

(Cuvier 1829) Round scad Forage Fish

Hypanus americana

(Hildebrand & Schroeder 1928) Southern stingray Reef-Associated Predator

Caretta caretta*

(Linnaeus 1758) Loggerhead sea turtle* Migratory Pelagic Predator

Acipenser oxyrhynchus*

(Mitchill 1815) Atlantic sturgeon* Anadromous Forage Fish

* Included via post-workshop assessments
24

● “Habitat” changed to “Species” throughout all worksheets

● Table 3 (Ecological Potential):

○ “Past evidence of recovery” changed to “dispersal”

○ “Physical diversity” changed to “phenotypic and behavioral plasticity”

○ “Biodiversity” changed to “genetic diversity”

○ “Keystone/indicator species” changed to “generalist/specialist ranking”

2.2 Overview of the RVA Tool

This section provides a brief summary of the RVA tool. Internet links to the full tool and 

instruction on its use are provided in Appendix C of this document, or can be found at the 

web address www3.cec.org/islandora/en/item/11739-north-american-marine-protectedarea-rapid-vulnerability-assessment-tool.

Steps 1 and 2

The RVA Tool determines the climate change vulnerability of a particular resource by 

guiding the participant through a series of thought steps. The first step guides the 

participant to define the scope and initial parameters of the assessment. This includes 

identifying the resource(s) to be assessed (e.g., habitats, species), the timescale over 

which climate impacts are being considered (e.g., next 50 years), and which climate 

change variables are likely to most greatly affect the resource(s). Because this is a rapid, 

rather than comprehensive assessment, not all resources or variables could be assessed. 

Using an initial list provided by GRNMS staff, workshop participants identified 11 

species for assessment. This list was based on existing knowledge of how the species 

responds to changes in its environment. The assessment focused on likely changes over 

the next 50 years, and participants identified three climate variables that would likely

have a consequential effect on a particular species. In general, the climate variables that 

were considered were supported by ample data and research. Some potential variables 

include sea level rise, turbidity, or increasing water temperature. Lastly in Step 1, 

participants are asked to consider what non-climate stressors currently affect the 

resource(s), such as harvesting, pollution, or dredging. The second step instructs the 

participant to transfer their input from the Step 1 boxes into the Step 3 (Assessment) 

tables. 

Step 3

Step 3 of the RVA is to construct a series of assessment matrices that establish three 

parameters: consequence, adaptive capacity, and vulnerability. Vulnerability is defined 

by the RVA tool as a combination of risk (likelihood and consequence of climate change 

impact) and adaptive capacity. Likelihood is the degree of certainty that an identified 

climate impact will occur. Consequence is found by examining the non-climate stressors 

affecting the resource and determining whether or not climate change will 
25

mitigate/exacerbate that stress. Adaptive capacity is a 1-5 (5 is superior) index of the 

resource’s ability to adapt or cope with stress inputs, both climatic and non-climatic. It is 

comprised of ecological potential (e.g., factors intrinsic to the resource, such as plasticity 

or genetic diversity) and social potential (extrinsic factors). Social potential includes 

considerations such as the capacity of a conservation organization to manage the resource 

(e.g., stakeholder relationships, stability, policy and science support). When risk and 

adaptive capacity tables have been completed, their results are added to the vulnerability 

table to derive a vulnerability score (Table 2.2).

Step 4

Step 4 in the RVA tool process is to generate and evaluate adaptation strategies and 

management responses that could potentially reduce the vulnerability of species with 

moderate or high vulnerability scores. In this part of the exercise, existing or achievable 

strategies that may lower risk or increase adaptive capacity, or both, are considered in the 

context of both cost and efficacy. Often, such measures are based upon a “3R” approach.

● Resistance – bolstering a resource’s ability to withstand a stress event 

● Resilience – improving a resource’s ability to recover from a stress event

● Response – aiding a resource in adapting to changed conditions

Once adaptation strategies and management actions have been identified, Step 4 prompts 

the participant to identify considerations for implementation, such as determining leaders 

and partners, monitoring needs, timeline, and funding mechanisms.

It should be noted that due to the rapid nature of this assessment and the fact that the 

majority of the participants were experts in the natural sciences, the adaptation strategies 

are not meant to be detailed enough to be ready for implementation. Instead, they are 

intended to be further explored by GRNMS staff as a follow-on to the RVA, in some 

cases with partners and stakeholders.

Table 2.2 Vulnerability (Risk x Adaptive Capacity) matrix (from Figure 3, RVA worksheets)

Risk

Adaptive Capacity

Low Moderate High

Low Low Low Low

Moderate Moderate Moderate Low

High High Moderate Moderate

Extreme High High Moderate
26

Step 5

Finally, Step 5 is to translate the RVA outcomes into a narrative vulnerability assessment 

report. This is a means to provide a summary of results, identified strategies, and key 

messages in a format that is easily shared and understood by potential stakeholders, 

partners, and the public. The results of the RVA for each species are presented in the 

following chapter (Ch. 3), both as tabular summaries (e.g., Table 3.1) and a narrative. 

Color coded rankings in the summary tables follow Table 2.3.

2.3 GRNMS RVA Workshop

The RVA workshop began with introductory presentations, including an overview of the 

goals/objectives of the meeting and the methods (detailed methods were provided in the 

pre-workshop webinar), as well as a basic summary of climate trends for the region (see 

Appendix A for workshop agenda). Because sanctuary staff identified species of interest 

for the assessment in advance of the workshop, time on the agenda was allowed for 

discussion and modification of this list by all participants. The final list of species 

assessed appears in Table 2.1. Based on these species identified for assessment, 

participants were allocated to one of three assessment break-out groups based on 

expertise and interest: invertebrates, reef fish, and pelagic fish.

Similarly, workshop participants were provided with a GRNMS climate summary and 

briefing from a NOAA climatologist (similar to Chapter 1 of this report) that helped 

inform their selection of climate factors of importance to the target species. Though there 

may be many climate stressors that affect a particular species, the rapid nature of the 

RVA tool promotes limiting the number of climate stressors to no more than three. 

Therefore, for each target species, workshop participants identified the three climate 

stressors they deemed most impactful to the species.

Table 2.3. Summary rankings and their color coding for the rapid vulnerability assessment exercise 

conducted for each species (from the CEC RVA tool, see also Appendix C).

Likelihood Almost 

Certain Likely Possible Unlikely Rare

Consequence Catastrophic Major Moderate Minor Negligible

Risk Extreme High Moderate Low

Adaptive 

Capacity Low Moderate High

Vulnerability High Moderate Low
27

The bulk of the workshop was spent in these smaller assessment groups, and each group 

completed three species assessment during this time. Species were assessed in these 

groups in order of information availability and interest from the participants, so the 

species assessed in this report do not necessarily reflect sanctuary species-related 

management or conservation priorities. Participants identified needed expertise in order 

to complete assessments for additional species of interest. The final hour of the workshop 

was spent summarizing the assessment results and discussing opportunities for 

collaboration regarding adaptation responses by management and scientific entities.

Given the limited time and targeted scope of the workshop, participants were instructed 

to focus solely on the selected species and provide assessment based on the information 

at hand and their expert knowledge. As such, this document, which is a workshop report, 

does not expand beyond the findings and outcomes of the workshop. While these findings

may also apply to other species, habitats, or geographies, doing so would require further 

assessment activity beyond the scope of the workshop or this report. 

Additionally, the adaptive strategies identified in this report are those that the workshop 

participants, in the limited time available to them, determined may reduce the 

vulnerability of the target species to climate change. These strategies are not 

recommendations for action to GRNMS, but rather identify some possible approaches, 

among others, that GRNMS staff may select for further consideration. 
28

3. Vulnerability Assessment and Adaptation 

Planning Results

This chapter presents the summary of vulnerability assessments of the 11 species 

examined by RVA workshop participants. It is divided into three sections: 

Invertebrates/Sessile Macrofauna, Reef Species, and Pelagic Species. The distinction 

between reef and pelagic species in the context of this report is that reef species are 

restricted to those that spend their full life cycle on or near the reef, while species 

considered pelagic are either migratory or are otherwise not fully dependent on the reef 

habitat.

Each section leads with a table that identifies the top three climate stressors identified for 

the species by workshop participants. For each stressor, the index/level of each step in the 

RVA is provided using the RVA worksheet terminology (e.g., high, medium, low) and 

color coded for reference to its likelihood or contributory impact, with green being most 

positive or least concerning, yellow as possible or moderate, red for likely or major 

concern, and purple for most likely, extreme or negative (see Table 2.3).

3.1 Invertebrates/Sessile Macrofauna

3.1.1 Stinking Vase Sponge (Ircinia campana)

Species overview

Benthic coverage of live-bottom ledge areas in Gray’s Reef is dominated by various 

species of sponges in the genera Ircinia and Chondrilla. The stinking vase sponge

(Ircinia campana) is a vase-shaped sponge, typically reddish-brown on the outside and 

tan inside (Fig. 3.1). The species ranges from the United States mid-Atlantic coast as far 

Table 3.1. Influence of climate change on stinking vase sponge from rapid vulnerability assessment 

scores.

Stinking Vase 

Sponge

Increased Water 

Temperature Turbidity Storm Severity/Frequency

Likelihood Almost Certain Almost Certain Almost Certain

Consequence Major Major Major

Risk Extreme Extreme Extreme

Adaptive Capacity High High High

Vulnerability Moderate Moderate Moderate
29

south as Brazil, and is also found 

throughout the Caribbean and 

Gulf of Mexico. This species 

also occurs in the Mediterranean 

Sea. They occur at depths 

ranging from 3 to 30 meters deep 

and are found on shallow hardbottom areas, seagrass beds, and 

inshore reefs. Within GRNMS, 

they are almost exclusively 

associated with the rocky ledges. 

The species is hermaphroditic 

and zygotes develop into freeswimming larvae before settling 

down onto a substrate to grow 

into sponges. 

The stinking vase sponge is the dominant sponge species within Gray’s Reef and plays an 

important ecological function in the benthic community. They are filter feeders, 

collecting food (phytoplankton, zooplankton, bacteria, etc.) while whipping seawater in 

through pores in their central body cavities. Sponges such as this species provide a 

variety of microhabitats for many invertebrate species (e.g., polychaetes are a dominant 

associated species off Georgia coast) by serving as refuge from predation, a food source, 

and an attachment site – all of which contribute to the stinking vase sponge providing an 

important ecological function on Gray’s Reef. The stinking vase sponge also provides an 

important maintenance (structural) function on the ledges within Gray’s Reef. As filter 

feeders, these sponges also provide a critical benthic-pelagic trophic coupling.

Vulnerability assessment results 

Workshop participants determined the climate change factors most likely to adversely 

affect the stinking vase sponge at GRNMS to be increased water temperature, turbidity, 

and changes in storm severity/frequency. The workshop participants decided these 

climate change stressors were all almost certain to occur in GRNMS. Additionally, 

tourism, disease (e.g., wasting disease), and altered sediment transport were identified as 

the most likely and important non-climate stressors that could adversely affect stinking 

vase sponges on Gray’s Reef. 

Seawater temperatures are anticipated to rise by 0.8 to 1.4°C by 2050. Thermal stress 

associated with ocean warming can greatly impact sponge assemblages through the 

induction of diseases and mortality by decreasing the efficacy of sponge defense 

mechanisms allowing for the development of pathogens. The threat from wasting disease 

to the stinking vase sponge may be exacerbated by climate change factors such as 

increased seawater temperatures, ocean acidification, and altered sediment transport 

Figure 3.1. Stinking vase sponge (Ircinia campana). (Image: 

Greg McFall, NOAA)
30

(urban/agricultural runoff). Thermal stress can limit reproductive capacity, limiting 

dispersal by causing reabsorption of spermatic cysts and oocytes and can even prevent 

the release altogether of asexual propagules. Thermal stress may impact sponge feeding 

by increasing filtration rates (warming temperatures) and decreasing choanocyte chamber 

density and size, causing shifts in microbial communities of the host sponge. Seawater 

temperature increases could lower the availability/concentrations of planktonic food 

washing through Gray’s Reef. This could lower sponge growth rates and reproductive 

capacity. Increased water temperatures, seasonally and/or year-round may impact 

plankton species composition as well that could also reduce sponge growth rates. The 

workshop group discussed that stinking vase sponge has a high adaptive capacity that 

drives down their vulnerability somewhat. The species has a wide dispersal distance but 

their habitat within Gray’s Reef is also patchy and largely limited to the rocky-ledge 

habitat within the sanctuary. As sessile invertebrates, changes in their prey species 

composition and distribution that result from seawater temperature increases, for 

instance, make the stinking vase sponge moderately vulnerable to climate change. 

Turbidity can cause a huge impact to sponges on Gray’s Reef by clogging sponge pores 

and reducing pumping/filtration capacity. Increased turbidity is anticipated as a result of 

increased storm severity in the area and from large-scale dredging projects (e.g., 

Savannah River). More intense storms may change wave height over Gray’s Reef in 

addition to changing wave period. These changes will increase turbidity during acute 

events and extend the time period before suspended materials settle after storms, 

especially if storm frequency increases as well. More extreme turbidity from storms may 

resettle benthic materials onto sponges, inundating them and inhibiting filtration feeding. 

Little change has occurred in the overall number of large storm events annually in recent 

years, hovering at about ten events per year. However, there has been a decrease in the 

number of weak storms with a greater percentage of annual storms being large storm 

events. Post-storm survey events have documented substantial scouring from recent 

Category 1 and 2 hurricanes. Projecting ahead, larger storms will likely increase sponge 

mortality in GRNMS and impede recovery of damaged sponges, especially if there is less 

of an interval between storm events. More intense storms may increase scouring of 

sponge habitat, increase sedimentation, either covering and/or clogging sponges, or 

displacing/upending sponges from their substrate. 

Potential adaptation strategies

The breakout group discussed one potential management response for the stinking vase 

sponge.

Develop a rapid response monitoring and assessment team

The most achievable option was to develop a rapid response monitoring and assessment 

team to assess damages from severe storm events (e.g., document damages from 

Hurricane Irma). The group suggested that such an assessment team approach be coupled 
31

to overlapping long-term monitoring and assessment sites within GRNMS. The success 

of such an approach is also dependent on the availability or establishment of species 

baseline data against which changes could be detected and assessed.

Cost: Low

Efficacy: High

3.1.2 Ivory Bush Coral (Oculina arbuscula)

Species overview

Compact ivory bush coral (Oculina arbuscula), also known as ivory tree coral, is a 

shallow water (< 100m) ahermatypic (non-reef building) scleractinia, or stony/hard coral 

(Fig. 3.2). With its tangled, branching skeleton, ivory bush coral crudely resembles a 

small bush or tree (hence its common name). Unlike their larger, deep water variant (O. 

varicosa), these colonizing corals 

appear brownish to yellowish as a 

result of the presence of 

zooxanthellae in the tissue. Ivory 

bush coral colonies reach 

approximately 60 cm (24 in) in 

diameter/height, with individual 

skeletal branches having a diameter 

of about 1.5 to 2.5 cm (0.5 to 1.0 

in) and closely spaced corallites 

(Reed 1980). The polyps are

facultatively symbiotic, fed both by 

their symbiotic zooxanthellae as 

well as suspension-feeding on 

planktonic microorganisms in the 

water column.

Table 3.2. Influence of climate change on compact ivory bush coral based on rapid vulnerability 

assessment scores.

Compact Ivory 

Bush Coral

Increased water 

temperature

Ocean 

Acidification

Storm 

severity/frequency

Likelihood Almost certain Likely Almost certain

Consequence Moderate Moderate Major

Risk High High Extreme

Adaptive Capacity High High High

Vulnerability Moderate Moderate Moderate

Figure 3.2. Compact ivory bush coral (O. arbuscula) on a 

ledge top in GRNMS (Photo: Greg McFall/NOAA).
32

Ivory bush coral is primarily found on the west coast of Florida, and on the Atlantic coast 

from Florida to South Carolina at depths between 3 and 30 m (10-33 ft). In GRNMS, it is 

relatively abundant, growing primarily on the tops of the rocky ledges at depths of around 

15 to 20 m (50 to 66 ft). This coral reproduces via annual broadcast spawning, usually in 

July or August. Miller (1995) demonstrated that ivory bush coral has a relatively broad 

temperature tolerance and that growth is significantly greater in warm water than cold 

water, though other studies (e.g., Shenkar et al. 2005) suggest that sustained temperature 

above 31°C produces bleaching in ivory bush coral colonies.

Owing to the limited light at depth (only around 6 percent of surface irradiance is 

available at 65 feet), many of the colonies found on vertical surfaces and beneath 

overhangs in Georgia waters exhibit permanent bleaching, but are nonetheless healthy 

(D. Gleason, 2018 pers. comm.).

Due partly to the protection its tangled structure provides as well as forming thickets on 

the substrate, ivory bush coral offers shelter to a wide variety of reef fish and 

invertebrates, and thus is an important keystone species and habitat. Like most 

zooxanthellae corals, ivory bush coral is susceptible to bleaching when stressed. 

Bleaching is the process by which zooxanthellae are expelled from the stressed coral’s 

tissue. Such stress has been associated with elevated (and suppressed) water 

temperatures.

The deep-water species of ivory bush coral (O. varicosa) is listed as threatened on the 

IUCN Red List as a result of substantial decline in abundance in a primary part of its 

range (Oculina Banks off Florida), where extensive removal has been attributed to 

bottom trawling (Reed et al 2007). There is insufficient information on shallow water 

ivory bush coral (O. arbuscula) to support an IUCN listing for the species. It is however 

included with O. varicosa by NOAA as a “Species of Concern” (see 

http://www.nmfs.noaa.gov/pr/pdfs/species/ivorybushcoral_detailed.pdf), primarily 

because its morphology makes it equally susceptible to damage from fishing activities 

(i.e., line entanglement, bottom trawling). Bottom trawling on hard bottom is now 

prohibited throughout the region, and part of GRNMS is closed to all fishing. Dredging, 

anchoring, and other bottom disturbance (including invertebrate collecting) is prohibited 

at GRNMS. However, other factors, such as scour or from passing storms may detach 

ivory bush coral from the substrate and sedimentation (burial) from storms also may 

adversely affect the species.

Vulnerability assessment results

The most likely climate change factors workshop participants concluded would affect

ivory bush coral at GRNMS were increased water temperature (e.g., SST), ocean 

acidification, and changes in storm behavior. The occurrence of these climate changes 

was deemed to be almost certain (increased temperature and storm behavior) and likely 
33

(ocean acidification) within GRNMS. Non-climatic stressors that may compound impacts 

were development/population growth, tourism/recreation (e.g., fishing, anchoring, marine 

debris), and altered sediment transport.

Thermally-induced bleaching of ivory bush coral has been observed within GRNMS, and 

the expected increase in water temperature of between 0.8°C and 1.4°C by 2050 may 

result in bleaching episodes of shallower colonies that have not experienced light-induced 

bleaching. Because ivory bush coral can sustain itself on plankton, thermal bleaching 

alone may not increase its mortality. It may however reduce photosynthesis and lower 

available planktonic food, thus reducing growth and fecundity of ivory bush coral. 

Water pH at GRNMS is expected to decrease by another 0.1 by 2050 to a seasonal range 

of 7.7 to 8.1, with the seasonal low pH decreasing at a higher rate than the seasonal high 

pH. This change is likely to reduce availability of carbonate that coral species can use to 

build their skeletons. Lower pH will also effectively reduce the availability of planktonic 

food sources. A laboratory experiment on Georgian ivory bush coral under elevated 

temperature and decreased pH is currently underway at Georgia Southern University (D. 

Gleason, 2018 pers. comm.). 

The number of storms (both tropical and extratropical) is not expected to change greatly, 

but a larger number of those storms are expected to produce extreme conditions. This 

shift toward stronger storms has potential to increase scouring and physical 

dislodgement/breakage of the corals. Remaining corals could be smothered with 

mobilized sediment. An expected decrease in the interval between major storms would 

exacerbate the problem and is likely to impede coral recovery.

Development and population growth in the coastal Georgia region through 2050 are

expected to alter freshwater runoff and produce an increase in nutrient and pollutant loads 

for GRNMS. Similarly, increased human population pressures are coupled to increased 

tourism/recreational use of GRNMS, which include increases in fishing and diving – both 

of which have demonstrated potential to damage corals. While these factors will likely 

moderately reinforce the negative impacts of increasing water temperature and ocean 

acidification, they are expected to provide a major exacerbation of negative effects of 

storm impacts (e.g., increased mobilization of marine debris, interference with post-storm 

recovery). Altered sediment transport is expected also to provide a negative 

accompaniment to the three climate stressors by increasing smothering of sessile species 

in some areas while scouring the benthic habitat in other areas. The combined impacts of 

sediment transport and increased water temperature along with ocean acidification are 

expected to result in an overall major negative impact to ivory bush coral, while the 

combined effect of altered sediment transport and changes in storm behavior is 

anticipated to be catastrophic.

As with the other sessile invertebrate species assessed by workshop participants, compact 

ivory bush coral at GRNMS were identified as having a high adaptive capacity to offset 
34

the potential impacts from climate change. The species is considered relatively abundant 

and fast-growing within GRNMS, and at least within the closed research area, any fishing 

or diving is prohibited. The species also is an ecologically-important species, but of little 

social/commercial value, limiting the likelihood of overharvesting (harvest is prohibited 

at GRNMS). Studies that have been done on ivory bush coral suggest limited larval 

dispersal (larvae tend to settle between one and three days). GRNMS may receive larval 

recruits from other habitats, and there has been demonstrated high recruitment on study 

tiles laid out on the ledges.

This high ecological potential for adaptation is somewhat offset by a lower social 

potential. While certain factors such as staff capability, monitoring ability, existing 

protections (e.g., CITES), scientific support, and stakeholder/partner relationships 

showed high adaptive capacity, other factors such as the capacity of existing staff 

(training/time) to engage in adaptation activities, responsiveness as a federal agency, and 

the overall societal value of ivory bush coral showed limited adaptation potential. The 

combination of ecological and social components set potential adaptive capacity for the 

species just above the moderate/high threshold.

Potential adaptation strategies

The high to extreme risk to ivory bush coral posed by climate change, coupled with a 

moderate (verging on high) vulnerability to that change, suggests the importance of 

planning and implementing adaptation strategies for this species. A number of potential 

strategies were discussed by workshop participants, and two were further explored.

Among the strategies identified as having high efficacy (but often at high cost) were 

establishing a lab-based Oculina nursery with water temperature controls to aid species 

adaptation to higher temperatures; installing artificial substrate (e.g., reef balls, artificial 

wrecks) to increase recruitment; outplanting to increase population densities; better 

education and enforcement for compliance in GRNMS public use to reduce marine debris 

and anchor damage; rapid restoration of damaged corals; removal of marine debris;

installation of permanent boat moorings; and transitioning monitoring instruments and 

activities from soft to hard funding to ensure longevity and consistency.

Three strategies that exhibited low cost and high efficacy were discussed: installing 

artificial substrate to promote recruitment and recovery; repairing anchor 

damage/removing marine debris; and increasing enforcement for compliance to reduce 

marine debris and anchor damage. 

Installing artificial substrate

GRNMS has permitting mechanisms already in place but funding is needed (perhaps 

from partner sportfishing clubs, diving groups, etc.). The anticipated 50-year time frame 

of this strategy includes a five-year installation plan, five-year evaluation period, and 

long-term monitoring. Complex substrate would increase Oculina recruitment and 
35

population density. However, while this strategy may be considered for the region outside 

of sanctuary boundaries, GRNMS has communicated to stakeholders that placing 

artificial substrate within sanctuary boundaries is unlikely.

Cost: Low

Efficacy: High

Reattaching dislodged ivory bush coral and removal of marine debris

While anchorage within GRNMS has been prohibited since 2007, dislodging of coral by 

illegal anchoring and other causes does occur occasionally. Adding this restoration 

component to existing in-water missions would be feasible without great additional costs 

to GRNMS or its partners. In most cases, individual corals can be reattached and smaller 

marine debris (e.g., cans, bags) can be removed by mission divers.

Cost: Low

Efficacy: High

Increasing compliance and enforcement

The latter strategy has immediate need with an indefinite time horizon. Awareness of and 

compliance with regulations at GRNMS can be enhanced through targeted education and 

outreach efforts by GRNMS staff and partners. NOAA or GRNMS partners would need 

to identify funds to support enforcement efforts. Lack of staff capacity to provide 

enforcement necessitates reliance on other agencies (e.g., Georgia DNR, U.S. Coast 

Guard, local law enforcement), and even private citizens (e.g., self-enforcement) to 

achieve results.

Cost: Low (if costs borne by other agencies)

Efficacy: High

An adaptation strategy that has already been adopted and is applied to GRNMS is the 

prohibition on bottom trawling, which Reed et al (2007) identified as a primary cause of 

damage to these corals. In addition, the research area of GRNMS is closed to all 

recreational and commercial water activities and vessel anchoring. With no plans to alter 

these restrictions, this strategy can continue at little to no cost but high efficacy.

3.1.3 Purple-Spined Sea Urchin (Arbacia punctulata)

Species overview

Arbacia punctulata (Fig. 3.3) is a shallow-water urchin (echinoid) found along the 

western Atlantic coast from Massachusetts south to Cuba, in the Gulf of Mexico along 

the Yucatan peninsula from Texas to Florida, throughout many locations in the Caribbean 

Sea, and along the coast of Panama to French Guiana. This species is usually found along 

shallow, sandy, rocky, shell-detritus bottom habitat, often found in association with turtle 

grass (Thalassia testudinum). Their depth range is from 0 to 225 meters (0 to 738 feet). 

The purple-spined sea urchin is a benthic forager on sessile invertebrates and algae and 

shifts its diets over different substrates (e.g., rubble, sand). They are generalist feeders 
36

with food availability being the primary factor controlling their diets. This species is 

ubiquitous within Gray’s Reef, in particular on or near the ledge habitat. Three years of 

urchin species/habitat data have been collected to date within and outside of the researchonly area on Gray’s Reef.

Vulnerability assessment results 

The most likely climate change factors by which workshop participants felt sea urchins at 

GRNMS might be affected were increased water temperature, ocean acidification, and 

changes in storm severity/frequency (Table 3.3). The workshop participants decided these 

climate change stressors ranged from possible to likely to occur in GRNMS. 

Additionally, development and 

population growth (e.g., runoff), 

tourism/recreation (increased use of 

GRNMS from fishing, diving, etc.), 

and altered sediment transport were 

identified as the most likely nonclimate stressors to occur and 

important stressors that could 

adversely affect purple-spined sea 

urchins. 

Seawater temperatures are anticipated 

to rise by 0.8 to 1.4°C by 2050. This 

temperature increase may affect the 

distribution and abundance of sea 

urchins throughout Gray’s Reef by 

altering their prey distribution in 

addition to altering their 

developmental and reproductive 

capacity. Over the next 50 years, 

Figure 3.3. Purple-spined sea urchin (Arbacia punctulata). 

(Photo: NOAA)

Table 3.3. Influence of climate change on purple-spined sea urchin from rapid vulnerability assessment 

scores.

Purple-Spined Sea 

Urchin

Increased Water 

Temperature Ocean Acidification Storm Severity/Frequency

Likelihood Almost Certain Almost Certain Likely 

Consequence Moderate Major Moderate 

Risk High Extreme High

Adaptive Capacity High High High

Vulnerability Moderate Low Moderate
37

seawater temperature increases could exceed thermal preference or tolerance for urchins 

on Gray’s Reef. The rates of such changes within GRNMS may exceed the species’ (or 

its prey’s) ability to adapt. Elevated seawater temperatures in the range of 28°C to 32°C 

have been demonstrated to impact important neuromuscular-mediated behaviors in 

urchins that could negatively impact population and community dynamics. Important 

behaviors such as covering (camouflage) used during the day, Aristotle’s lantern reflex 

(feed intake), and righting behavior may all be negatively affected by elevated seawater 

temperatures. This may cause urchins to migrate northward (outside of Gray’s Reef) 

seasonally or altogether if temperature tolerances are exceeded. This migratory shift 

would affect trophic dynamics within GRNMS. Increases in seawater temperature may 

also cause a shift from a diet currently dominated by invertebrate prey to a more algaldominated diet for resident urchins. Elevated seawater temperatures will likely reduce 

efficient use of resources in urchins, reducing their feeding efficiency and reproductive 

capacity.

Ocean acidification is increasing both globally and locally (Gray’s Reef) with a seasonal 

pH fluctuation from 8.2 to 7.8. Projections are that pH will shift downward (greater 

acidity) another 0.1 by 2050 (seasonal variation from 7.7 to 8.1). The seasonal low pH is 

decreasing at a faster rate than the seasonal high. Greater variability between seasonal 

lows and highs in pH are anticipated. Increasingly acidified seawater with decreased 

available carbonate material would negatively affect both urchin prey and urchins 

themselves. Urchin larvae exposed to acidified seawater have reduced growth rates, 

delayed development, and overall stunted growth. Urchins exposed to increased ocean 

acidification reduce their mean body size and experience reduction in arm growth and 

supporting skeletal rods. Decreases in aragonite saturation levels also will lower 

availability of planktonic food, further impacting urchin foraging.

Recent changes in the severity of storms could impact urchins on Gray’s Reef. The 

annual number of storms has changed little in recent years, hovering at about 10 storms 

per year. However, there has been an increase in the number of major (category 4/5) 

storms annually. More intense hurricanes will increase mortality (e.g., cracked open 

when slammed into rocks) and increase scouring of available habitat and prey species as 

evidenced by recent storms in 2017 (e.g., Hurricane Irma). 

Potential adaptation strategies

Develop a rapid response monitoring and assessment team

As with ivory bush coral, develop a rapid response monitoring and assessment team to 

assess damages from severe storm events (e.g., document damages from Hurricane Irma). 

Probably pair this with overlapping long-term monitoring and assessment sites within 

GRNMS.

Cost: Low

Efficacy: High
38

Continue ongoing urchin research

Continue ongoing urchin research inside/outside the research-only area. Some of this 

research should continue to focus on correlations between climate change stressors and 

urchin population size, habitat use, dietary shifts, and short- and long-term recovery after 

storm events. 

Cost: Low

Efficacy: High

3.2 Reef Species

3.2.1 Black Sea Bass (Centropristis striata)

Species overview

The black sea bass (Centropristis striata) is a temperate marine species that inhabits 

irregular hard-bottom areas, such as wrecks or reefs. Its range extends along the U.S. 

Atlantic coast from Cape Cod to the Florida Keys and in the Gulf of Mexico. Those 

found in the South Atlantic Bight usually occur inshore with tropical reef fish such as 

snappers, groupers, porgies, and grunts. They are often found in bays and sounds, and 

offshore to a depth of around 130 m (430 ft). They tend to avoid the open water column, 

instead spending a large proportion of time near the sea bed, often gathering around 

protruding formations such as rocks, artificial reefs, wrecks, pilings, and piers.

These fish are grey to black in color (juveniles may be a dusky brown), with a long dorsal 

fin transitioning from spiny to soft ray appearance (Fig. 3.4). They can attain a maximum 

size of 50 cm (20 in) and weight of 4.6 kg (10 lb.). Black sea bass are protogynous 

hermaphrodites; that is, they change sex with size, all starting out as females. Large 

individuals are males, and smaller individuals are female, with the transition occurring at 

a length between 24 and 33 cm (Provost et al. 2017). They spawn once mature, which 

occurs roughly at a size of around 19 cm (7.5 in.). The spawning season is February 

Table 3.4. Influence of climate change on black sea bass from rapid vulnerability assessment scores.

Black Sea Bass Increased water 

temperature Altered Currents Storm Severity/Frequency

Likelihood Almost certain Possible Likely

Consequence Major Moderate Moderate

Risk Extreme Moderate High

Adaptive Capacity High High High

Vulnerability Moderate Low Moderate
39

through May in the South 

Atlantic Bight. Their eggs are 

buoyant and develop in one to 

two days. Black sea bass may 

live up to 20 years, although 

fish older than nine years are 

rare. Black sea bass are 

opportunistic feeders that will 

generally eat any available 

food, preferring crabs, shrimp, 

worms, small fish, and clams. 

Black sea bass are a 

commercially- and 

recreationally-valued species 

for fishers, and as such have 

the potential to be overfished. 

Quotas, seasons, and 

management actions are in place for the species in the South Atlantic Bight. According to 

the South Atlantic Fisheries Management Council3

, for commercial operations there is 

minimum size limit of 279 mm (11 in.) and a pot fishing prohibition in the vicinity of 

GRNMS that extends from November 1 to April 30. Recreational fishers may take up to 

seven fish per person per day, with no closed season and minimum fish length of 330 mm 

(13 in.). Total annual catch limit is 822,817 kg (1,814,000 lbs.), with a commercial limit 

of 353,811 kg (780,020 lbs.), and a recreational limit of 469,005 kg (1,033,980 lbs.) 

across their managed geography.

Vulnerability assessment results

Workshop participants evaluated black sea bass in Gray’s Reef to have a low to moderate 

relative vulnerability to climate change. While the participants estimated major to 

moderate consequences to climate and non-climate stressors and high likelihood of future 

climate changes, the final vulnerability score was lowered due to the black sea bass’ 

expected high adaptive capacity. 

Workshop participants identified the most significant climate stressors and non-climate 

stressors on black sea bass population in Gray’s Reef. The three most significant climate 

stressors were increased water temperature, altered currents, and increased storm severity 

and frequency. 

Sea surface temperatures are expected to increase by 0.8 to 1.4°C by 2050. This 

temperature change may result in a northward distribution shift for black sea bass, and 

 3 Information from: http://safmc.net/regulations/regulations-by-species/black-sea-bass/

Figure 3.4. Black sea bass (Centropristis striata). (Photo: 

Karsten Shein/NOAA)
40

thus a corresponding decrease in population at Gray’s Reef as water temperature there 

warms. It may also result in changes in their reproductive season and operational sex 

ratio (ratio of fertilizable females to sexually mature males) as well as shorten their larval 

stage, which could create mismatches with available food sources (trophic-level 

disruptions). 

Shifts in direction and intensity of currents are expected, partly as a result of the 

increased sea surface temperature. This would include the Florida Current/Gulf Stream, 

which could potentially shift eastward. Changes in current could affect larval recruitment 

and, again, create mismatches with available food sources. 

Storm severity and frequency is expected to change with fewer but more intense storms; 

however, it is difficult to estimate what impacts that may have on such a small area as 

Gray’s Reef. Storms can have direct effects on the species’ preferred habitat such as 

physical destruction or smothering of the reefs as well as changes in salinity near the 

coast where larval transport occurs. Increasing frequency of storms may coincidentally 

reduce the recovery period for black sea bass between major storm events. 

The three most significant non-climate stressors were identified as land source pollution, 

harvest, and altered sediment transport (which could smother preferred habitats). Land 

source pollution, both nutrient and non-nutrient, is likely to result in lower salinity and 

impact water quality in other ways (e.g., nitrogen and phosphorous flux increases, 

decreasing dissolved oxygen, etc.), which could increase mortality of larval and juvenile 

stages in nearshore brackish and estuarine habitat. At the same time, increased nutrient 

loads could benefit plankton productivity, which would be beneficial to both juvenile and 

adult black sea bass depending on the nutrient input and plankton species affected. Land 

source pollution is likely to increase with more intense storm events due to climate 

change. 

Fishing is limited to recreational captures in GRNMS; however, the overall population is 

dependent on commercial and recreational fishery management in the region. Current 

management measures may become less effective with a northward distribution shift 

resulting in a smaller population in the southern portion of their range. The ecological 

potential of black sea bass is high, due to its wide distribution, large population, high 

dispersal potential, early maturation, and generalist feeding nature. The social potential is 

also high, because it is a valuable fishery with high investment in monitoring and 

management.

Potential adaptation strategies

Workshop participants identified a number of strategies which if implemented could 

reduce the vulnerability of black sea bass to climate change. These strategies were as 

follows.
41

Promoting awareness: Black sea bass as climate change ambassador

Because GRNMS is at the southern edge of the black sea bass range, the species may not 

persist in the sanctuary as temperatures warm and the species’ range shifts northward. 

However, this provides an opportunity to use black sea bass as a climate change outreach 

tool, targeting a sector generally disengaged from discussing the impacts of climate 

change. Black sea bass is the most popular recreational fishing target species in GRNMS. 

Successful outreach could alter the public’s perception and behavior with respect to CO2

emissions reduction or other climate stressors, as well as result in higher public 

engagement (e.g., influence elected officials). 

Cost: Low. 

Efficacy: Low (it may not prevent a northward shift of black sea bass, but may have 

long-term beneficial effects by increasing awareness on climate change and mobilizing 

people to take action).

Reducing threat of lionfish invasion: Trapping lionfish

One of the central roles of a marine reserve is to enhance native biotic resistance to 

threats such as the climate and non-climate threats outlined above. Invasive lionfish 

settling within GRNMS is a major potential threat to black sea bass. As the population of 

black sea bass declines due to increasing temperatures, more invasive lionfish might 

move into GRNMS to fill the black sea bass ecological niche. The increased presence of 

lionfish, also opportunistic feeders, could result in black sea bass having increased 

competition for food sources such as tomtate (Ballew et al. 2016), reducing species 

carrying capacity, changing size distributions, and even reducing fecundity. If lionfish

populations increase substantially in GRNMS, it stands to reason that juvenile/smaller 

black sea bass would be preyed upon by adult lionfish, further tipping the population 

numbers in favor of lionfish at the expense of black sea bass. As potential prevention of 

this, GRNMS could deploy lionfish traps, such as those designed by Gittings et al. 

(2017), to mitigate a lionfish invasion. Knowing that lionfish are likely to colonize from 

the deep-water areas offshore from GRNMS, the sanctuary could focus on deploying 

traps between GRNMS and the deep-water aggregation areas in a few source locations 

from where lionfish are likely to migrate into GRNMS. While this would not help the 

decline of black sea bass population due to climate change stressors, it would help 

maintain biodiversity at GRNMS and not add another stressor (lionfish) that might 

accelerate black sea bass decline.

Cost: High. 

Efficacy: Medium (it may be very effective for GRNMS but of a low spatial scale 

overall; hopefully, only a few source locations offshore seed GRNMS with lionfish,

probably related to inshore current flow).

Reducing threat of lionfish invasion: Encouraging lionfish fishery

Similar to what has been done at Flower Garden Banks National Marine Sanctuary,

GRNMS could develop a public outreach to encourage a recreational fishery for lionfish, 

introducing the concept of lionfish as a good food source. Lionfish can be caught by hook 

and line, usually by divers and spearfishers. Currently, the number of lionfish in GRNMS 
42

is low but it is likely to grow over time. Initially, GRNMS could suggest adding a lionfish

catching contest as part of an existing fishing derby (with a special prize for lionfish 

catch in addition to the regular derby prizes). The ongoing lionfish derbies in the Florida 

Keys that were organized initially by the Reef Environmental Education Foundation 

would provide a good template to start at GRNMS. When lionfish becomes more 

abundant on GRNMS, a stand-alone lionfish contest could be created.

Cost: Medium. 

Efficacy: Medium.

Monitoring for climate change: Using GRNMS as ecological reference point

Using GRNMS as an ecological reference point (ERP) for black sea bass (and other 

species) would provide a logical, efficient place to monitor the effects of climate change 

with respect to distributional shift (northward) and arrival of more southern species. By 

using GRNMS as an ERP, NOAA would capitalize on the presence of the research area 

to distinguish between the effect of fishing and climate change. This may require an 

increase in the research area size to more effectively capture influence of fishing vs. 

climate change impact. Ideally, the research area size should be several times the home 

range of targeted species. The information gathered as part of this ERP would benefit 

fisheries management (states, commission, and council) as well.

Cost: High. 

Efficacy: High (it may not prevent northward shift of black sea bass but may provide 

tangible, significant monitoring information about climate change effects on regional 

species composition).

3.2.2 Tomtate (Haemulon aurolineatum)

Species overview

The tomtate (Haemulon aurolineatum) is a relatively small grunt. This schooling fish is 

silver-white with a brownish-yellow stripe that runs the length of its body from the eye to 

a black spot at the base of the caudal fin (Fig. 3.5). The inside of their mouth is bright 

Table 3.5. Influence of climate change on tomtate based on rapid vulnerability assessment scores.

Tomtate Increased Water 

Temperature Turbidity Storm Severity/Frequency

Likelihood Almost certain Likely Likely

Consequence Negligible Negligible Minor

Risk Low Low Moderate

Adaptive Capacity Moderate Moderate Moderate

Vulnerability Low Low Moderate
43

red, giving rise to colloquial 

names of red mouth or 

blood mouth grunt. Tomtate 

range from Cape Hatteras to 

northern Brazil, and are 

prevalent in southeast U.S.

waters. Tomtate spawn in 

spring, and reach sexual 

maturity within five years 

and a mature size between 

14 and 16.5 cm (5.5-6.5 

in.). They may attain a 

maximum size of around 30 

cm (12 in.) and a weight of 0.5 kg (1.1 lbs.). Tomtate preferred habitats are the rough 

bottom areas (e.g., reefs and live-bottom such as GRNMS) found along the continental 

shelf throughout their range. These fish are rarely seen in waters cooler than 12°C (54°F). 

Tomtate generally feed on bottom-dwelling invertebrates and are in turn an important 

prey species for many piscivore reef species such as barracuda and king mackerel. 

Tomtate are not heavily fished and do not regard divers as a threat. Because they are not 

prized by sport or commercial fisheries, tomtate fisheries are not heavily regulated, with 

no size or trip/bag limits, but general grunt landings in the South Atlantic (U.S.) are 

managed under NOAA annual catch limits (ACL).

Vulnerability assessment results

The most likely climate change factors to which workshop participants felt tomtate at 

GRNMS might be affected were increased water temperature (e.g., SST), increased 

turbidity, and changes in storm behavior. The occurrence of these climate changes was 

deemed to be likely to almost certain for GRNMS. Additionally, harvest (i.e., incidental 

bycatch in non-target fisheries), noise, and altered sediment transport were identified as 

the primary non-climatic stressors currently affecting tomtate, but the impact of these on 

tomtate were determined to be ephemeral and largely negligible.

Water temperatures at GRNMS are expected to increase by 0.8 to 1.4°C by 2050. As with 

other species, this will likely facilitate a northward expansion of the tomtate range. 

However, because GRNMS is not at the southerly extent of the range, increased water

temperature and northerly range extension is unlikely to produce a population decline at 

GRNMS. It is possible, however, that an earlier warm up in spring may affect spawning 

times and reduce larval duration. Overall, the effect of warming water on tomtate was 

considered neutral

The increase in water temperature, coupled with more frequent intense rain events and 

more intense storm systems, may result in increased sediment load, algal blooms, and 

turbidity. These changes could potentially reduce visibility, which may benefit a 

Figure 3.5. Tomtate (Haemulon aurolineatum). (Photo: NOAA)
44

schooling species such as tomtate, as schooling fish are normally preyed upon by visual 

predators. The net effect may be a decrease in natural mortality from predation. 

Conversely, tomtate may have more difficulty foraging for prey given reduced visibility 

in their environment. 

A shift to fewer but more intense storms affecting GRNMS is likely to produce habitat 

disturbance via physical damage and sediment smothering. These effects may impact 

tomtate food sources by scouring the sea bed and increasing mortality of their 

invertebrate food sources. 

Tomtate at GRNMS were identified by workshop participants as having moderate 

adaptive capacity to offset the impacts of climate change. The species is widely 

distributed, with GRNMS at the northern edge of its range. High genetic diversity is 

thought likely, given the population size, and tomtate exhibit high phenotypic/behavioral 

plasticity and are of high value to the ecosystem. However, while their ecological 

adaptive capacity is high, their social potential is moderate. There is no accepted stock 

assessment of the species, their socioeconomic value is low, they are not individually 

managed (all grunt species are managed in aggregate), and there is limited scientific 

research on the species. These limitations are offset by relatively good monitoring 

capacity and a proactive conservation management approach by GRNMS staff and 

stakeholders.

Potential adaptation strategies

Given the relatively low vulnerability of tomtate to climate change, potential adaptation 

strategies were not discussed during the workshop. However, as part of this RVA, 

GRNMS has identified tomtate as a species of ecological importance to the habitat. Such 

an identification promotes monitoring for changes in the species that correspond to 

changing environmental conditions. At present, GRNMS in conjunction with partners 

monitors species such as tomtate within its boundaries and has set aside a research area in 

which public access is prohibited. GRNMS also maintains a strong outreach and 

educational focus which has the capacity to inform the public and key stakeholders about 

any observed or forecast changes in tomtate as a result of climate change.

3.2.3 Northern Red Snapper (Lutjanus campechanus)

Species overview

The northern red snapper (Lutjanus campechanus) is a species of snapper native to the 

western Atlantic Ocean including the U.S. Atlantic coastal waters and the Gulf of 

Mexico, where it commonly inhabits reef environments. The northern extent of its range 

in U.S. waters is currently around Cape Cod, Massachusetts. Red snapper occupy water 

between nine and 90 m (30 to 300 ft) and favor reefs, rocky bottom, ledges, ridges, 

wrecks, and other habitats with vertical relief. They often gather in large schools of 
45

relatively uniform-sized individuals. Like black sea bass and other reef-based fish, red 

snapper normally remain close to the sea bottom.

Northern red snapper are pink to red in color and have a typical snapper profile, with a 

sloped head, medium-sized scales, and spiny dorsal fin (Fig. 3.6). Unlike other snapper, 

red snapper have short, needle-like teeth. At maturity, red snapper are around 39 cm (15 

in.) total length, and adults commonly attain a size of around 60 cm (24 in.). The 

maximum recorded size and weight is 1 m (39 in.) and 38 kg (84 lbs.). Red snapper can 

live many decades, with specimens living beyond 100 years. A northern red snapper

attains sexual maturity at two to five years old. However, fecundity is correlated to age 

and size with larger/older females producing greater numbers of better-quality eggs. The 

spawning season is April through August in the South Atlantic Bight.

Northern red snapper move to different types of habitats during their growth and 

development. When they are newly spawned, red snapper settle over large areas of open 

benthic habitat, often congregating around oyster beds. They gradually move to highrelief reefs such as GRNMS at about two years of age. Red snapper tend to have high site 

fidelity, only moving about a mile or so from their adult settling location (Szedlmayer 

and Shipp 1994). 

Northern red snapper are 

a prized food fish 

historically and today, 

caught commercially as 

well as recreationally. 

Red snapper is the most 

commonly caught 

snapper in the continental 

U.S. (almost 50 percent

of the total catch), with 

similar species being 

more common elsewhere. 

Figure 3.6. Northern red snapper in GRNMS. (Photo: Greg 

McFall/NOAA)

Table 3.6. Influence of climate change on red snapper from rapid vulnerability assessment scores.

Red Snapper Increased water 

temperature Altered Currents Storm Severity/Frequency

Likelihood Likely Possible Almost Certain

Consequence Moderate Minor Moderate

Risk High Moderate High

Adaptive Capacity Moderate/High Moderate/High High

Vulnerability Moderate Low Moderate
46

To address population decline, both recreational and commercial bag limits have been 

established since the 1980s, with recent years seeing a closure of both commercial and 

recreational landings for the South Atlantic region. However, short commercial and 

recreational fishing seasons were reinstated in 2018 

(http://safmc.net/regulations/regulations-by-species/red-snapper/). Commercial fishing 

for snapper in federal waters requires a federal permit. Open seasons in 2019 remain 

uncertain.

Vulnerability assessment results

Workshop participants evaluated red snapper in Gray’s Reef to have moderate relative 

vulnerability to climate change. According to estimates from the participants, the 

consequences of climate and non-climate stressors were minor to moderate and the 

likelihood of future climate changes varied from possible to almost certain, with an 

overall risk estimated to be moderate to high. The final vulnerability score was influenced 

by the red snapper moderate to high adaptive capacity.

Workshop participants identified the most significant climate stressors and non-climate 

stressors on red snapper population in Gray’s Reef. The three most significant climate 

stressors were increased water temperature, altered currents, and increased storm severity 

and frequency. Sea surface temperatures are expected to increase by 0.8 to 1.4°C by 

2050. This temperature change may result in a northward distribution shift for red 

snapper, with Gray’s Reef potentially gaining in population size. It may also result in 

changes in their reproductive season as well as shorten their larval stage, which could 

create mismatches with available food sources. Warmer sea surface temperature might 

result in increased growth rate; however, this species already exhibits rapid growth rate 

so this is not expected to result in significant changes.

Shifts in direction and intensity of currents are expected, partly as a result of the 

increased sea surface temperature. This would include the Florida Current/Gulf Stream, 

which could potentially shift eastward. Changes in current could affect larval recruitment 

and, again, create mismatches with available food sources. 

Storm severity and frequency is expected to change with fewer but more intense storms; 

however, it is difficult to estimate what impacts that may have on such a small area as 

Gray’s Reef. Storms can have direct effects on the species’ preferred habitat such as 

physical destruction or smothering of the reefs as well as changes in salinity and coastal 

discharge and nutrient load near the coast where larval transport occurs. We would also 

anticipate impacts to red snapper prey and prey habitat from increasingly intensified 

storms that could indirectly impact red snapper populations within GRNMS.

The three most significant non-climate stressors were identified as harvest, invasive 

species, and altered sediment transport (which could smother preferred habitats). Harvest 

is limited to recreational fishing in GRNMS; however, the overall population is 
47

dependent on commercial and recreational fishery management in the region. Fishing 

pressure may increase with an increasing population size due to warmer waters moving 

north; however, it is unclear whether the fishery management would be precise enough to 

avoid overfishing. Without intervention, the invasive species red lionfish (Pterois 

volitans) is likely to become more established at Gray’s Reef with increasing water 

temperatures, and they are excellent competitors with red snapper, which may have 

negative effects on the red snapper population. Lionfish have high reproductive rates, low 

parasite load, defensive venomous spines, and are habitat generalists and efficient 

predators. These factors all make red lionfish a dangerously well-suited competitor to red 

snapper should they establish themselves on Gray’s Reef.

Although red snapper experienced overfishing in the second half of the 20th century, its 

ecological potential is high due to its wide distribution, large population, high dispersal 

potential, early maturation, and generalist nature. The social potential is moderate. Even 

though red snapper is a highly managed fish species, there is a lack of information on 

climate impacts to red snapper and the current management framework is not yet suited 

to monitor those impacts.

Potential adaptation strategies

Reducing threat of lionfish invasion: Trapping lionfish

As movement of invasive lionfish into GRNMS is likely enhanced due to increasing 

water temperature, lionfish are likely to outcompete red snapper and to fill the ecological 

niche red snapper currently occupy, resulting in a declining population of red snapper. 

GRNMS could deploy lionfish traps (e.g., Gittings et al. 2017) to mitigate lionfish

invasion. Knowing lionfish are likely to colonize from the deep-water areas offshore 

GRNMS, the sanctuary could focus on deploying traps between GRNMS and deeper 

water. This would help prevent the displacement of red snapper population and maintain 

biodiversity at GRNMS.

Cost: High. 

Efficacy: Medium. It may be very effective for GRNMS (local extirpation with sustained 

efforts) but of a low spatial scale overall.

Reducing threat of lionfish invasion: Encouraging lionfish fishery

Similar to what has been done at Flower Garden Banks and Florida Keys national marine 

sanctuaries, GRNMS could develop a public outreach to encourage a recreational fishery 

for lionfish, introducing the concept of lionfish as a good food source. Currently, the 

number of lionfish in GRNMS is low but is expected to grow. Some possibilities to 

involve fishers in lionfish extirpation may include sponsoring lionfish derbies in adjacent 

waters, or holding controlled culls within the sanctuary (excluding the research area). 

Such methods, initiated in tandem with offshore fishing traps, may provide an effective 

one-two punch to hold lionfish in check in GRNMS.

Cost: Medium. 

Efficacy: Medium.
48

Monitoring for climate change: Using GRNMS as an ecological reference point

Using GRNMS as an ecological reference point (ERP) for red snapper (and other species) 

would provide a logical, efficient way to monitor the effect of climate change with 

respect to distributional shift (northward) and arrival of more southern species. By using 

GRNMS as an ERP, NOAA would capitalize on the presence of the research area to 

distinguish between the effect of fishing and climate change. This may require an 

increase in the research area size to more effectively capture the influence of fishing vs. 

climate change impact, especially as red snapper biomass appears higher outside the 

current research area due to the greater abundance of tall ledges outside the research area 

(R. Muñoz, SEFSC, pers. comm.). Ideally, the research area size should be several times 

the home range of targeted species. The information gathered as part of this ERP would 

benefit fisheries management (states, commission, and council) as well.

Cost: High. 

Efficacy: High (it may not prevent effects of a changing climate but may provide 

tangible, significant monitoring information about climate change effects on regional 

species composition).

3.3 Pelagic Species

3.3.1 King Mackerel (Scomberomorus cavalla)

Species overview

The king mackerel (Fig. 3.7) is a fast-swimming piscivore. It is found in both the 

nearshore and offshore waters throughout its range in the Western Atlantic, from Canada 

down through South America, including the Caribbean Sea and Gulf of Mexico. King 

mackerel prefer water temperatures above 20°C (68°F) and migrate to warmer waters in 

the fall of the year. They are oceanadromous, often found on outer reef areas. Their depth 

range is between five to 140 m (~16 to 460 ft) deep but they are most often found 

between five to 15 m (~16 to 50 ft) depth. They primarily feed on schooling bait fish 

Table 3.7. Influence of climate change on king mackerel based on rapid vulnerability assessment 

scores.

King Mackerel Increased Water 

Temperature Altered Currents Altered Upwelling/Mixing

Likelihood Almost Certain Likely Likely

Consequence Major Minimum Minimum

Risk Extreme Moderate Moderate

Adaptive Capacity High High High

Vulnerability Moderate Low Low
49

(e.g., round scad, also found 

on Gray’s Reef, see section 

3.3.2), penaeid shrimp, and 

squid (Saloman and Naughton 

1983). Large schools of king 

mackerel have been 

documented to migrate over 

great distances along the 

Atlantic U.S. coast and they 

are mostly limited by cooler 

water temperatures 

(Sutherland and Fable 1980). 

King mackerel are highly sought after as game fish. There are regulated commercial and 

recreational fisheries for king mackerel in addition to artisanal fisheries throughout their 

range. Common length is about 70 cm (28 in) and their maximum lifespan is reported to 

be approximately 13 years (Beaumariage 1973). In the southeastern U.S., king mackerel

spawn spring through summer. Approximately 50 percent of both males and females

mature at about two years. The species is currently not over-exploited and is managed as 

two separate stocks, the Western Atlantic stock and the Gulf of Mexico stock, which mix 

in winter off south Florida. 

Vulnerability assessment results 

The three most likely climate change factors by which workshop participants felt king 

mackerel at GRNMS might be affected were increased water temperature, altered 

currents, and altered upwelling/mixing. The most impactful non-climate stressors 

identified were harvesting (commercial and recreational), aquaculture, and 

underwater/overwater structures. 

Water temperatures at GRNMS are expected to increase by 0.8 to 1.4°C by 2050. This 

increasing water temperature may coerce king mackerel into a northerly range extension 

but it is questionable whether this shift would mean a commensurate decline within 

GRNMS. It may however, affect the timing of occurrence of king mackerel within and 

near GRNMS, which could have economic repercussions for the region (e.g., fishing 

tournaments). Regional increases in water temperature may also incline congener species 

such as Spanish mackerel (Scomberomorus maculatus) to move into the region with 

unknown ecological and economic ramifications. 

Similarly, altered currents resulting from projected changes in the eddies shed from the 

Gulf Stream could change king mackerel seasonal distribution and stock mixing. These 

shifts in aggregations of king mackerel may also impact spawning and occurrence of 

eggs/larvae and cause trophic level shifts. 

Figure 3.7. King mackerel (Scomberomorus cavalla). (Photo: 

Stephen Ewen)
50

Altered upwelling/mixing may result from prevailing wind changes, changes to the 

Bermuda High, wave period, and changes in eddies/currents. Some changes in 

upwelling/mixing could benefit prey such as round scad, creating more food for them in 

addition to benefiting larval stages of king mackerel. Overall for all climate change 

stressors identified, these are anticipated to possibly change the seasonal distribution and 

abundance of king mackerel within GRNMS but mackerel have a low to moderate 

vulnerability to these stressors and a high adaptive capacity. 

Potential adaptation strategies

The three adaptive management strategies for king mackerel and round scad (see Sec. 

3.3.2) are identical.

Develop a regional response network

Develop a regional response network that will respond to climate stressors impacting 

king mackerel. This strategy carries over for all pelagic species assessed and the idea is to 

work with the South Atlantic Fishery Management Council (SAFMC) to adjust

management strategies for fully protected MPAs that recognize the relationship between 

pelagic and benthic species based on research from GRNMS. This would establish a 

network of MPAs across the southeast U.S. that builds resilience to climate change. 

Cost: Low

Efficacy: Moderate

Develop a rapid response monitoring and assessment team

Develop a rapid response monitoring and assessment team to assess damages from severe 

storm events (e.g., document damages from Hurricane Irma). This should be paired with 

overlapping long-term monitoring sites within GRNMS.

Cost: Low

Efficacy: High

Identify source areas for lionfish

Lionfish recruitment and localized control is an active area of research throughout the 

Southeast U.S. and Caribbean, and GRNMS has habitat topography conducive to 

explosive proliferation of the species if not addressed. This strategy would identify 

source areas for red lionfish recruitment onto Gray’s Reef and develop collaborations to 

extirpate lionfish at these source areas. GRNMS could develop a strategic plan that 

fosters collaboration among diving groups, harvesters, and universities. Tying lionfish

harvesting into active research could enhance results. If lionfish source areas are 

diver/trap accessible (e.g., manageable depths and distance from shore), this strategy

could help in other lionfish hotspot areas (e.g., Florida Keys National Marine Sanctuary). 

Consider pathways for any scientific harvesting to provide harvested lionfish samples to 

NOAA and other agencies/universities conducting studies on this invasive species. 

Cost: Moderate

Efficacy: High
51

3.3.2 Round Scad (Decapterus punctatus)

Species overview

The round scad (Fig. 3.8) 

is a shoaling fish species 

inhabiting neritic waters, 

often near sandy bottom. 

The Western Atlantic 

population ranges from 

Nova Scotia southward 

through the Gulf of 

Mexico and Caribbean to 

Brazil. The maximum 

length for this species is 

about 30 cm (12 in) total 

length but typically adults usually reach about 18 cm (7 in) length. They are a 

macrofauna predator, feeding primarily on planktonic invertebrates, usually copepods, 

but also on gastropod larvae, pteropods, and ostracods. They are resilient with a high 

population doubling time of 15 months. Round scad are generalists, feeding in the water 

column. They are fished heavily in Georgia, mostly as a bait fish, and there is not a 

managed fishery for them. 

Vulnerability assessment results 

The most likely climate change factors to which workshop participants felt round scad at 

GRNMS might be affected were ocean acidification, altered upwelling/mixing, and 

changes in storm severity/frequency. The workshop participants decided these climate 

change stressors were possible to likely to occur within GRNMS. Additionally, invasive 

Figure 3.8. Round scad (Decapterus punctatus). (Photo: NOAA)

Table 3.8. Influence of climate change on round scad based on rapid vulnerability assessment scores.

Round Scad Ocean 

Acidification

Altered 

Upwelling/Mixing

Storm 

Severity/Frequency

Likelihood Likely Possible Possible

Consequence Moderate Negligible Moderate

Risk High Low Moderate

Adaptive Capacity High High High

Vulnerability Moderate Low Low
52

species (e.g., red lionfish), altered sediment transport, and harvesting were identified as 

the most likely and important non-climate stressors to adversely affect round scad.

Ocean acidification has the potential to decrease pH to 7.8 over the timeframe assessed. 

Ocean acidification will impact invertebrate communities on which round scad feed, but 

which invertebrate prey species will be most affected remains unknown. It is anticipated 

that structural invertebrates (benthic ledge invertebrate species in particular) as well as 

copepods will be adversely impacted, disrupting round scad foraging patterns and maybe 

precluding them from feeding inside GRNMS if threshold pH levels are exceeded for key 

prey species. Vulnerability was assessed at moderate for the ocean acidification threat 

because of the impacts to scad invertebrate prey.

Altered upwelling/mixing was identified as an important climate-influenced risk to scad 

although there are not a lot of data to anticipate the magnitude and type of changes in 

store. Wind force, flow, changes in the Bermuda High, and wave period/intensity all will 

influence upwelling/mixing over GRNMS. Changes in upwelling could impact prey 

distribution, reproductive capacity, and temperature thresholds of both scad and its prey 

species. Seawater temperatures above 15°C (59°F) could impact spawning. However, 

round scad are believed to use GRNMS primarily for foraging so impacts to prey 

distribution may be the greatest threat from changes in upwelling/mixing. Overall, the 

pelagic group assessed the vulnerability to scad as low from upwelling/mixing because 

they could forage elsewhere following changes in prey distribution and abundance.

Storm severity/frequency was also assessed as an important climate stressor that could 

impact round scad. There is considerable uncertainty in predictive models for this threat, 

although any changes in storm intensity and frequency are bound to impact prey 

distribution of invertebrate species that inhabit both the benthos and water column. More 

severe storms are already occurring in the region and as they continue these storms may 

impact CO2 concentrations, pulling CO2 from the sediment with lower pH. More intense 

storms may scour the available hardbottom ledge habitat and inundate other areas with 

sediment – both of which would impact scad prey abundance and distribution. The group 

found that scad have a low vulnerability to this threat because their foraging habits are 

flexible and presumably they would move to other areas where prey are abundant during 

recovery periods after storm events. The duration and frequency of storms over time may

lead to long-term impacts on prey availability.

Potential adaptation strategies

Overall, vulnerability of round scad to climate change was deemed low to moderate. 

Three adaptation strategies were discussed, which are identical to those identified for 

king mackerel (see sec. 3.3.1). 
53

Develop a regional response network that will respond to climate stressors 

Develop a regional response network that will respond to climate stressors affecting 

GRNMS. This strategy carries over for all pelagic species assessed. The idea is to 

influence the SAFMC to alter management strategies for fully protected MPAs that 

recognize the relationship between pelagic and benthic species based on research from 

GRNMS. This would establish a network of MPAs across the southeast U.S. that builds 

resilience to climate change. 

Cost: Low

Efficacy: Moderate

Develop a rapid response monitoring and assessment team

Develop a rapid response monitoring and assessment team to assess damages from severe 

storm events (e.g., document damages from Hurricane Irma). Probably pair this with 

overlapping long-term monitoring and assessment sites within GRNMS.

Cost: Low

Efficacy: High

Identify source areas for lionfish

Round scad have been identified as a prey species of red lionfish, P. volitans (Peake et al. 

2018; Dahl and Patterson 2014). Thus, a strategy could be to identify source areas for 

lionfish that are recruiting onto Gray’s Reef and develop collaborations to extirpate 

lionfish at these source areas before they can recruit into GRNMS. Develop a strategic 

plan that fosters collaboration among different diving groups, harvesters, universities. 

Best would be to tie the lionfish harvesting into active research on this invasive species. 

If the lionfish source areas are diver/trap accessible (i.e., suitable depths, distance from 

shore), this extirpation method could help in other lionfish hotspot areas (e.g., Florida 

Keys National Marine Sanctuary). 

Cost: Moderate

Efficacy: High

3.3.3 Southern Stingray (Dasyatis americana)

Table 3.9. Influence of climate change on southern stingray based on rapid vulnerability assessment 

scores.

Southern Stingray Diminished Dissolved 

Oxygen Ocean Acidification

Likelihood Unlikely Possible

Consequence Minimum Moderate

Risk Low Moderate

Adaptive Capacity High High

Vulnerability Low Low
54

Species overview

The southern stingray (Fig. 

3.9) is a coastal marine and 

estuarine species with a wide 

distribution in the Western 

Atlantic from New Jersey 

south through the Gulf of 

Mexico and into the 

Caribbean Sea south to Brazil. 

It is a commonly sighted 

species in GRNMS, although 

the species has declined 

throughout its range mostly 

due to bycatch in various 

commercial fisheries. There 

are targeted fisheries in some 

countries (e.g., Brazil, 

Venezuela) but none in the 

United States. The species is listed as threatened on the IUCN Red List (worldwide 

distribution) and also as a species of concern for NOAA/NMFS; however, populations in 

the U.S. are generally abundant (e.g., west coast of Florida in Gulf of Mexico, coastal 

areas along the southeastern U.S.). Southern stingrays are most often associated with 

sand flats, seagrass beds, and coral reefs, at depths from 0 to 53 m (0 to 174 ft). Their diet 

consists of benthic and infaunal invertebrates and demersal teleosts. Common prey are 

decapod crustaceans such as alphaeid, penaeid and calliansid shrimp and brachyuran 

crabs. Southern stingrays usually bury themselves partially in the sand during the day and 

forage at night. They feed by creating depressions in the sand, exposing invertebrates and 

small fishes. Southern stingrays are ovoviviparous and after a gestation period of four to 

five months, they typically have three to four pups per litter.

Vulnerability assessment results 

The most likely climate change factors to which workshop participants felt southern 

stingray at GRNMS might be affected were diminished dissolved oxygen and ocean 

acidification. We discussed that only these two climate threats warranted consideration 

given the offshore location of GRNMS location and the life history and habitat use of this 

species. The consensus of the group discussion was that rising seawater temperature 

would not be a concern for the southern stingray given the projected increase in 

temperature from 0.8 to 1.4°C by 2050 and the thermal tolerance of this species. 

Similarly, with non-climate stressors, the workgroup identified just 

development/population growth (impacts to estuarine habitat) as a potential non-climate 

stressor for the species. Invasive species (i.e., red lionfish) and electric fields (e.g., 

underwater telecommunications cabling) were discussed but not a significant threat to 

Figure 3.9. Southern stingray (Hypanus americanus). (Photo: 

Karsten Shein/NOAA)
55

consider further. Harvest as indirect bycatch in fisheries may be regionally relevant but 

the group felt this threat was not specific to Gray’s Reef. 

As seawater temperatures rise, dissolved oxygen levels may drop appreciably that in turn 

may change the abundance and distribution of invertebrate prey for the southern stingray. 

Lower available dissolved oxygen at or near to the benthos, while unlikely to reach 

biologically harmful levels as it has elsewhere (e.g., northern Gulf of Mexico), will likely 

reduce the abundance and possibly also the diversity of prey species available to southern 

stingrays inside GRNMS. Depending on levels of dissolved oxygen, rays may not be able 

to tolerate bottom habitat and would move to more amenable areas with higher dissolved 

oxygen levels for foraging/resting/pupping.

Ocean acidification has the potential to decrease pH to 7.8 over the timeframe assessed. 

Ocean acidification will impact the benthic invertebrate community that the southern 

stingray, a benthic forager, feeds upon, in the extreme case causing trophic cascades. It is 

anticipated that structural invertebrates (benthic ledge invertebrates but also borrowing 

and motile invertebrates in sandy areas) will be adversely impacted by ocean 

acidification, disrupting southern stingray foraging patterns and maybe precluding them 

from feeding inside GRNMS if threshold pH levels are exceeded for key prey species. 

Vulnerability was assessed as low for both ocean acidification and diminished dissolved 

oxygen, largely because of the adaptive capacity of southern stingrays to move into areas 

less impacted by climate change stressors.

Potential adaptation strategies

Overall, vulnerability of southern stingrays to climate change was deemed low because 

they are common throughout Gray’s Reef and the region, they have a wide-variety of 

prey selection (opportunistic generalists), and GRNMS provides ample suitable habitat to 

this species. Some adaptation strategies were discussed, but ultimately, only one was 

selected as feasible from a cost/efficacy standpoint. 

Increase monitoring of dissolved oxygen levels within GRNMS

The adaptation strategy advanced by the workshop was to increase monitoring of 

dissolved oxygen levels within GRNMS and assess the effects of diminished dissolved 

oxygen levels on benthic prey species for southern stingrays. The same should be done 

for increased pH levels within GRNMS. Monitor pH levels and look for shifts in benthic 

prey communities in terms of abundance and species richness. Perhaps sediment core 

sampling could be added to existing monitoring/sampling regimes in and out of the 

research-only area.

Cost: Moderate

Efficacy: High
56

3.3.4 Loggerhead Sea Turtle (Caretta caretta) [Northwest Atlantic (NWA) Distinct 

Population Segment (DPS)]

Species overview

The loggerhead sea turtle (Fig. 3.10) is one of seven extant sea turtle species in the world 

and was listed as threatened under the Endangered Species Act (ESA) throughout its 

global range in 1978. NOAA Fisheries and the U.S. Fish and Wildlife Service (USFWS)

published a final rule designating nine DPSs for loggerhead sea turtles on September 22, 

2011. Critical Habitat 

under the ESA was 

established for the NWA 

DPS of loggerheads in 

August 2014 for marine 

areas. Specific areas for 

designation include 38 

occupied marine areas 

within the range of the 

Northwest Atlantic 

Ocean DPS. These areas 

contain one or more of 

the following habitat 

types: nearshore 

reproductive habitat, 

winter area, breeding 

areas, constricted 

migratory corridors, 

Table 3.10. Influence of climate change on NWA DPS loggerhead sea turtles based on rapid 

vulnerability assessment scores (not conducted during workshop).

NWA DPS Loggerhead 

Sea Turtle

Storm 

Severity/Frequency

Ocean 

Acidification

Diminished 

Dissolved Oxygen

Likelihood Likely Almost Certain Likely

Consequence Major Catastrophic Catastrophic

Risk High Extreme Extreme

Adaptive Capacity High High High

Vulnerability Moderate Moderate Moderate

Figure 3.10. Loggerhead sea turtle (Caretta caretta). (Photo: NOAA)
57

and/or Sargassum habitat. USFWS issued a final rule for critical habitat for terrestrial 

areas (nesting beaches) separately from NOAA Fisheries designation.

The NWA DPS of loggerhead sea turtles is the DPS that associates with Gray’s Reef 

National Marine Sanctuary. Loggerheads are large sea turtles with relatively large heads, 

which support powerful jaws that enable them to feed on hard-shelled prey such as 

whelks and conch. Adults in the southeastern United States average about 3 feet (92 cm)

long, measured as a straight carapace length, and weigh approximately 255 pounds (116 

kilograms). Within the NWA DPS, most loggerhead sea turtles nest from North Carolina 

to Florida and along the Gulf Coast of Florida. The majority of loggerhead nesting in the 

southeastern U.S. (~80 percent) occurs in six Florida counties. The Archie Carr National 

Wildlife Refuge in Brevard and Indian River counties accounts for about 25 percent of all 

loggerhead nesting in the United States. Loggerheads are long-lived animals. They reach 

sexual maturity between 20 and 38 years of age, although age at maturity varies widely 

among populations. 

The annual mating season occurs from late March to early June, and female turtles lay 

eggs throughout the summer months. Females deposit an average of 4.1 nests within a 

nesting season, but an individual female only nests every 3.7 years on average. Each nest 

contains an average of 100 to 126 eggs which incubate for 42 to 75 days before hatching. 

Loggerhead hatchlings are 1.5 to 2.0 inches long and weigh about 0.7 ounces (20 grams). 

As post-hatchlings, loggerheads hatched on U.S. beaches enter the “oceanic juvenile” life 

stage, migrating offshore and becoming associated with Sargassum habitats, driftlines, 

and other convergence zones. The Northwest Atlantic Loggerhead Recovery Team 

defined the following eight life stages for the loggerhead life cycle, which include the 

ecosystems those stages generally use: (1) egg (terrestrial zone), (2) hatchling stage 

(terrestrial zone), (3) hatchling swim frenzy and transitional stage (neritic zone4

), (4) 

juvenile stage (oceanic zone), (5) juvenile stage (neritic zone), (6) adult stage (oceanic 

zone), (7) adult stage (neritic zone), and (8) nesting female (terrestrial zone). It is 

primarily in the adult stage (neritic zone) that loggerheads inhabit Gray’s Reef NMS. 

Adult loggerheads forage on a wide variety of invertebrate species including bryozoans, 

crabs, urchins, and other sessile and motile organisms. Within Gray’s Reef, loggerheads 

primarily forage and take refuge on and near the limestone ledges. This preferred habitat 

makes up less than 5 percent of the overall habitat within the sanctuary.

Vulnerability assessment results

The workshop participants did not complete a vulnerability assessment for loggerheads, 

but rather, it was agreed upon by participants that an RVA was needed for this species 

and the RVA was completed directly after the workshop by Joe Cavanaugh. Cavanaugh

 4 Neritic refers to the nearshore marine environment from the surface to the sea floor where water depths 

do not exceed 200 meters.
58

used the information about Gray’s Reef ecology, climatology, staffing capacity, 

partnerships, etc., in consultation with sea turtle experts Mark Dodd (Georgia DNR), 

Dennis Klemm (NOAA Fisheries) and others to assess potential impacts to loggerheads 

at Gray’s Reef from projected climate and non-climate stressors.

Loggerhead sea turtles (NWA DPS) have a moderate relative vulnerability to climate 

change considering their marine life history stages apart from nesting/hatching stages 

(e.g., beach/sand temperature/moisture affecting sex ratio of hatchlings in nests leading to 

bias in females; Sifuentes-Romero et al. 2017). Although generally quite vulnerable to 

climate change impacts, regionally in Gray’s Reef loggerheads are less vulnerable given 

their use of Gray’s Reef as foraging adults. Climate change stressors will likely have a 

greater impact on nesting habitat, for instance, than on the offshore sanctuary. 

Loggerhead vulnerability is still moderate because of projected adverse impacts to 

loggerhead prey within the sanctuary. It is likely that both prey abundance and species 

richness will be adversely impacted by climate change stressors. The most significant 

climate stressors affecting loggerhead sea turtles are: (1) storm severity/frequency; (2) 

ocean acidification; and, (3) diminished dissolved oxygen – all three of which are 

anticipated to adversely impact the invertebrate prey community that attracts loggerheads 

into the sanctuary, especially around the ledge habitat that provides preferable foraging 

and resting habitat for loggerheads. 

Increased storm intensity/frequency may impact loggerhead prey (e.g., urchins, 

bryozoans, crabs, etc.) in both the short-term (acute events) and long-term 

(sedimentation, scouring) of important invertebrate habitat. Shifts in prey distribution and 

abundance may reduce loggerhead use of habitat within Gray’s Reef, making them seek 

alternative, possibly lesser-quality foraging and resting habitat outside of the sanctuary. 

These shifts in foraging patterns may reduce loggerhead fitness, forcing them to expend 

more energy foraging in lesser-quality habitat than exists presently in Gray’s Reef. This 

also may reduce their reproductive fitness. 

Diminished dissolved oxygen levels in GRNMS are anticipated over the next 50-year 

period. As dissolved oxygen levels are reduced seasonally and possibly year-round in

GRNMS, monitoring of the benthic invertebrate community may reveal changes in 

distribution and abundance that would in turn impact loggerhead foraging. The ledge 

habitat within Gray’s Reef currently provides good quality foraging habitat in addition to 

important vertical relief habitat (< 5 percent of Gray’s Reef habitat) where loggerheads 

prefer to rest. 

Increased ocean acidification is also anticipated at Gray’s Reef and would be expected to 

adversely impact the benthic invertebrate community on the ledges on which loggerhead 

sea turtles depend. Increased ocean acidification will impact some species at first more 

than others, but as thresholds for different species are exceeded, there will likely be 

wholesale community shifts in the communities occupying the more vulnerable ledge 
59

habitat possibly leading to trophic cascades and the disappearance of some important 

prey species within Gray’s Reef. 

Potential Adaptation Strategies

Rapid response team to assess storm damage

Develop a rapid response team to assess damage to benthic habitat both in terms of sand 

deposition and damaged benthic community in and around ledges where not just 

loggerheads but most of the important biomass is concentrated. Focus on post-storm 

assessments as soon after the events as possible. Compare results to baseline monitoring 

(transects, roving diver, belt transects – whatever methodologies best suited to those 

ledge habitats), and link to broader loggerhead habitat monitoring and assessment efforts 

where available. Also assess changes in salinity, temperature, and dissolved oxygen after 

storm events to compare with baseline data. Near to real-time damage assessments on 

Gray’s Reef could be correlated to storm intensity, track, seasonality, etc. These data 

would help management prepare long-term strategic planning and aid species/habitat 

vulnerability reassessments. This strategy would help sanctuary managers secure funding 

targeted to protect species most at risk from climate change impacts. And based on 

RVAs, GRNMS could target funding to those most vulnerable species that also have the 

highest adaptive capacities. 

Cost: Moderate to High.

Efficacy: High.

Climate and loggerhead prey monitoring

Establish long-term (e.g., 50 years) monitoring of climate variables (abiotic factors such 

as salinity, temperature, dissolved oxygen, beyond existing NOAA buoy data) and 

loggerhead prey species affected (benthic invertebrates). This strategy would also include 

the addition of a sea turtle expert to the GRNMS Sanctuary Advisory Council. Also, this 

strategy would add sea turtles to any fish assemblage/invertebrate monitoring plans (if 

not already included).

Cost: Moderate.

Efficacy: High.
60

3.3.5 Atlantic Sturgeon (Acipenser oxyrhynchus oxyrhynchus)

The Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is an anadromous species 

(spawns in freshwater in spring/early summer, then migrates into estuarine/marine 

habitats where it spends the majority of its life). Atlantic sturgeon attain lengths up to 14 

feet (425 cm) and weights up to 800 lbs. (363 kg). They are bluish black or olive brown 

dorsally with paler sides and a white ventral surface, and have five major rows of dermal 

scutes (Fig. 3.11). They are long-lived (60 years) and age at maturation shows latitudinal 

variation with faster growth and earlier age at maturation in more southern systems, 

probably around five to 19 years of age in Georgia. Regional upriver spawning begins in

February or March in Georgia. Atlantic sturgeon do not spawn every year. Instead,

spawning intervals range from one to five years for males and two to five years for 

females. Fecundity of Atlantic 

sturgeon is correlated with age and 

body size (ranging from 400,000 to 

8 million eggs). Females typically 

exit rivers within four to six weeks 

after spawning, whereas males may 

remain in rivers/low estuaries until 

the fall. 

The species range is along the 

Atlantic coast of the U.S. from 

Maine to northern Florida (Fig. 

3.12), with the nearest spawning 

site to GRNMS being the Altamaha 

River. Historically, Atlantic 

sturgeon were harvested in the 

Altamaha River in a commercial 

Table 3.11. Influence of climate change on Atlantic sturgeon based on rapid vulnerability assessment 

scores (not conducted during workshop).

Atlantic Sturgeon Diminished 

Dissolved Oxygen

Altered Precipitation 

Patterns

Storm 

Severity/Frequency

Likelihood Almost Certain Almost Certain Likely

Consequence Catastrophic Major Major

Risk Extreme High High

Adaptive Capacity Moderate Moderate Moderate

Vulnerability High Moderate Moderate

Figure 3.11. Atlantic sturgeon (Acipenser oxyrinchus 

oxyrinchus). (Photo: USFWS)
61

fishery until 1997, when it was closed due to severe overfishing. Recent genetic analysis 

showed that the Altamaha River population is distinct from neighboring populations in 

Ogeechee and Savannah rivers. Overall, genetic diversity for species is surprisingly low. 

There are only two rivers with enough Atlantic sturgeon for population size estimates, the 

Altamaha and Hudson Rivers. There are five Distinct Population Segments (DPSs) of 

Atlantic sturgeon, all of which are designated either as threatened or endangered under 

the Endangered Species Act: the Chesapeake Bay, New York Bight, Carolina, South 

Atlantic, and Gulf of Maine populations. All five DPSs are currently utilizing GRNMS. 

Species recovery time is estimated to require the next 40 years at least. Currently the 

species is in the early stages of recovery after 10+ years of federal protection. In 

Georgia, Atlantic sturgeon has a skewed young-age structure (oldest 17 years old from 

recent 2011 study) from previous overharvesting. 

Demographic and genetic diversity concerns led to their listing under the Endangered 

Species Act in 2012 and then designation of critical habitat in 2016. Many of the major 

rivers in Georgia are listed as 

critical habitat for the species that 

include the Savannah, Ogeechee, 

and Altamaha rivers. The 

Altamaha River is nearest to 

Gray’s Reef and is listed as 

critical habitat for the South 

Atlantic DPS of Atlantic sturgeon

(Figs. 3.12 and 3.13).

Atlantic sturgeon utilize GRNMS 

for foraging (adults) and

nearshore estuarine and river 

habitats for migration, spawning,

and juvenile development. The 

Altamaha River is the nearest 

spawning site to GRNMS for this 

species (~ 21 mi from SW corner 

of the sanctuary). Atlantic 

sturgeon foraging on GRNMS 

are primarily consuming benthic 

invertebrates in the sand and mud 

with their protrusible mouths, 

suctioning benthic prey such as 

amphipods, polychaetes, and 

mussels and shrimp off the 

substrate. Figure 3.12. Image showing Atlantic Sturgeon range and 

approximate location of Gray’s Reef (white arrow). (Image: 

Rich and Tursi, 2012)
62

The species faces numerous threats, including habitat destruction/alteration, harvesting 

(direct fisheries until the 1990s), and indirect bycatch in current fisheries targeting other 

species. There is also concern over non-indigenous pathogens being introduced from 

aquaculture. Furthermore, water flow, river/seawater temperature, dissolved oxygen, 

salinity, hard-bottom substrate (necessary for eggs to stick), and pollutant concentrations

are all important factors in successful spawning and larval development. NOAA Fisheries 

estimates that Atlantic sturgeon are present in 35 rivers ranging from St. Croix, Maine, to 

the Saint Johns River, Florida, but are spawning in only about 20 of these rivers. 

For purposes of this RVA, our action area is Gray’s Reef and the nearby rivers such as 

the Altamaha and Savannah rivers. Climate and non-climate stressors that impact the 

nearby rivers and estuaries will also influence sturgeon use of Gray’s Reef. For instance, 

a climate stressor (e.g., altered precipitation patterns) may have more of an adverse 

impact on sturgeon in the nearby Altamaha River where spawning occurs than on Gray’s 

Reef because of elevated risk to successful spawning. A non-climate stressor such as 

land-source nutrient and non-nutrient pollution would also likely impact sturgeon in the 

Altamaha River more heavily than offshore at Gray’s Reef because the pollution would 

Figure 3.13. Gray’s Reef in relation to Atlantic Sturgeon critical habitat (rivers in red). Yellow pin 

identifies the mouth of the Altamaha River. (Source: 2017 Google)
63

impact a more vulnerable life-stage in-river (spawning females and progeny) than 

offshore (foraging adults).

Vulnerability assessment results

The workshop participants did not complete a vulnerability assessment for Atlantic 

sturgeon, but rather, participants agreed that an RVA was needed for this species and the 

RVA was completed directly after the workshop. Workshop participant Joe Cavanaugh 

led this assessment, using information about Gray’s Reef ecology, climatology, staffing 

capacity, and partnerships that were identified during the workshop. Consulting on this 

assessment were Atlantic sturgeon experts such as Andrew Herndon, NOAA Fisheries

Atlantic Sturgeon Coordinator, and others to assess potential impacts to Atlantic sturgeon

on Gray’s Reef and nearshore habitat including spawning rivers from projected climate 

and non-climate stressors.

Atlantic sturgeon has a moderate to high relative vulnerability to climate change. Their 

vulnerability is elevated due to life history stages spent in estuaries and rivers where the 

identified climate and non-climate stressors will be magnified in both relative scale to 

those habitats and because rivers in particular are weighted more heavily in terms of 

habitat usage for sturgeon than Gray’s Reef habitat. In other words, stressors that 

adversely affect rivers will affect vulnerable life history phases of sturgeon that occur 

while they occupy those rivers (e.g. spawning adults, egg, embryo, and young-of-the-year 

survival) more than life stages spent as adults on Gray’s Reef (foraging habitat). 

However, GRNMS staff will presumably also have less direct influence over decision

making for those most vulnerable areas outside of the sanctuary borders. Yet there are 

opportunities for GRNMS staff to become more involved in coastal management decision 

making – especially given the identified interconnectivity for sturgeon between nearby 

river and nearshore coastal habitats and Gray’s Reef. 

The most significant climate stressors and non-climate stressors on Atlantic sturgeon

population in Gray’s Reef were assessed. The three most significant climate stressors 

were diminished dissolved oxygen, altered precipitation patterns, and storm severity and 

frequency. A fourth climate stressor, salinity, was also assessed because salinity is such 

an important factor in the diadromous life cycle of the species, outside of Gray’s Reef in 

the estuaries and rivers where they spawn and early embryonic and juvenile survival 

depends. The non-climate stressors assessed were land-source nutrient and non-nutrient 

pollution, harvesting (bycatch in fisheries), and dredging. 

Although non-climate stressors are not addressed in this summary, dredging bears 

mentioning. The Savannah Harbor Expansion Project began in 2017 and this dredging 

project is impacting Atlantic sturgeon that may visit Gray’s Reef. This project to date 

(NOAA Fisheries Incidental Take Data) has relocated 120 live sturgeon through 

relocation trawls as of January 10, 2018, and killed six to eight sturgeon between the 

project’s four hopper dredges in service. One live sturgeon was also found on a hopper 
64

dredge in December 2017. The captures in this project to date indicate that this estuary is 

being heavily used by Atlantic sturgeon because they are aggregating seasonally possibly 

in higher numbers than previously anticipated. Projects like this may have a more 

immediate impact than climate change stressors on sturgeon use of Gray’s Reef by 

possibly disrupting reproductive behaviors leading to diminished returns of adults 

foraging on Gray’s Reef.

Very low dissolved oxygen levels may impact sturgeon prey abundance on Gray’s Reef 

but more immediately affect Atlantic sturgeon in their coastal estuarine and riverine 

habitats. Even slightly diminished dissolved oxygen levels can have a much greater 

impact at spawning sites within river habitats than would be expected with similar 

diminished dissolved oxygen levels on Gray’s Reef, for instance, where adults forage 

over very large areas.

As with diminished dissolved oxygen, altered precipitation pattern will have less of an 

impact on Gray’s Reef than in nearby estuary and river habitat sturgeon utilize during 

their most vulnerable life stages. Altered precipitation patterns cause increases/decreases 

in rainfall distribution that can dramatically impact river habitat (flow, bottom habitat, 

predator/prey interactions, habitat niche partitioning, nutrient flow, pollutant dispersal, 

and important abiotic factors). The seasonal timing and precipitation pattern changes 

(e.g., summer flooding) for anadromous fish like sturgeon may undermine successful 

spawning or embryo survival for that spawning season. Female Atlantic sturgeon may 

spawn every two to five years, so the potential loss of an entire reproductive effort can 

profoundly impact species recovery. 

Storm severity and frequency changes would likely impact estuary and river habitat more 

immediately and acutely than at Gray’s Reef. Also, within Gray’s Reef, the sand/mud 

bottom would probably not be as adversely impacted as the productive ledges within the 

sanctuary. Sturgeon are primarily feeding in the soft sand sediment that account for over 

95 percent of the Gray’s Reef habitat. Sturgeon benthic prey also have relatively fast 

recovery rates, such as four to six weeks for amphipods and polychaetes, that would 

allow a quicker recovery time for sturgeon foraging than if they were foraging the ledges 

themselves. Outside of very large storms/hurricanes, we expect less disruption to Atlantic 

sturgeon on Gray’s Reef than to nearshore and upriver where these habitats may suffer 

greater impacts from storm events coincident with the most vulnerable life-stages for 

sturgeon. 

Sturgeon life history as an anadromous species reveals that its vulnerability and adaptive 

capacity is inextricably tied to the species use of both marine and freshwater habitats. In 

this case, sturgeon are more vulnerable to climate change stressors when they occupy the 

rivers and nearshore estuarine habitats. However, it is unknown what threshold levels 

exist whereby climate change stressors would make Atlantic sturgeon not use habitat 

within Gray’s Reef.
65

Potential adaptation strategies

Developing rapid post-storm response team

Develop a rapid response assessment SCUBA diving team that could visit storm 

impacted areas of Gray’s Reef as soon as possible after large storm events (e.g., 

Hurricane Irma, 2017). Team would complete standardized assessments to storm-affected 

areas but likely have longer-term control sites for monitoring as well. Metrics to monitor 

would include species composition, sand deposition, and damage to ledge habitat. If 

acoustic arrays are set up eventually, they could determine how quickly sturgeon come 

back into affected area post-storm events. Acoustic arrays would also give data on 

temporal/spatial usage patterns of Gray’s Reef and these data could be interrelated to 

other nearshore sturgeon datasets. Sturgeon habitat use/movement data would help 

management prepare long-term strategic planning and assist in re-assessing 

species/habitat vulnerability for the sanctuary. 

Cost: Moderate to high.

Efficacy: High.

Add acoustic tagging array to Gray’s Reef for Atlantic sturgeon

Possibly piggyback on existing acoustical arrays that are set up inshore for sturgeon by 

university and Georgia state researchers. This would establish sturgeon usage patterns for 

Gray’s Reef, seasonality, size-class of individuals, and connectivity between GRNMS 

and estuary and river use (nearshore acoustical arrays already in place) would provide 

important data largely absent for determining extent that Atlantic sturgeon uses GRNMS. 

It is possible that GRNMS could leverage Federal Section 10 funds to purchase arrays at 

a cost of around $2,000 apiece. Areal coverage of GRNMS would need to be established 

to determine the number of arrays needed.

Cost: Moderate.

Efficacy: High.
66

4. Conclusions and Next Steps

Gray’s Reef is one of the largest near-shore “live-bottom” reefs of the southeastern 

United States. Its ledges and outcroppings provide habitat to many marine species and 

attract pelagic predators. Gray’s Reef is protected and managed by Gray’s Reef National 

Marine Sanctuary, which undertook a rapid vulnerability assessment in order to better 

understand and manage for climate change and the effects it may have on the reef and its 

denizens. 

Environmental conditions at GRNMS are expected to continue to change between now 

and 2050. The temperature of the water is expected to increase, on average, between 0.8 

and 1.4°C, relative to the 1999 annual average. The pH of the water is anticipated to 

decrease by an additional 0.1 to around 7.8 over that same period. Climate models also 

suggest shifts in atmospheric pressure and precipitation. Pressure shifts are expected to 

alter the position of the Bermuda High, which influences both the atmospheric circulation 

over GRNMS as well as the behavior and positioning of the subtropical gyre, Florida

Current, and Gulf Stream. These changes are connected to anomalous warm and cool 

water incursions to GRNMS, though there is insufficient information to determine trends 

in such events. Precipitation totals are unlikely to change greatly in the Southeast, but the 

frequency, duration, and geographic pattern of regional precipitation favor a trend toward 

higher variability, producing more extremes. Droughts are likely to become longer lasting 

and more widespread, while precipitation events are likely to be more intense. This has 

the potential to concentrate river discharge and sediment/nutrient flows into GRNMS at 

greater concentrations than at present. Similarly, although little change is predicted in the 

number of cyclonic storm systems (both tropical and extratropical) affecting the area, 

atmospheric changes are anticipated to produce an increase in the number of those storms 

that reach major categorization. Thus, there is an increased likelihood of storm-related 

damage to GRNMS over the next 30 years or so.

Of the several aforementioned climate change factors, storm severity/frequency, 

increased water temperature, ocean acidification, altered currents, and diminished 

dissolved oxygen were identified as influencing the climate vulnerability of the most 

species assessed (Table 4.1).

A trend toward more major tropical and extratropical storms impacting GRNMS was 

identified as a major impact to many species, particularly sessile invertebrates that would 

suffer from physical damage/detachment and possible sediment smothering as a result of 

passage of a major storm system. Participants deemed this impact as likely, which when 

coupled by non-climate stressors (RVA Consequences) produced a high risk of impact.
67

The second most identified climate stressor was increased water temperature. This factor 

was likely to shift mobile populations northward, possibly away from GRNMS; reduce 

fecundity; and facilitate competition by invasive species (e.g., red lionfish). Occurrence 

Table 4.1. Median rankings for the five most identified climate impacts on the 11 species assessed in 

the GRNMS RVA. Note that workshop participants only identified the top three climate stressors, thus, 

other lesser climate stressors may affect a given species but were not considered.

GRNMS 

Workshop 

Results

Storm 

Severity/

Frequency

Increased 

Water 

Temperature

Ocean 

Acidification

Altered 

Currents

Diminished 

Dissolved 

Oxygen

Trend to 2050

Little change in 

total number of 

tropical 

cyclones. 

Increase in 

percentage of 

major cyclones. 

Increase in 

strength of 

extratropical 

cyclones.

Increase of 

between 0.8 

and 1.4 ̊C 

(annual avg.). 

Greater 

seasonal 

variability.

Decrease in 

pH by an 

additional 

0.1. 

Aragonite 

undersaturation 

expected in 

temperate 

water by 

2050.

Decreased 

transport 

rates in 

Florida 

Current. 

Shift in 

median track 

of Gulf 

Stream. 

Southerly 

limit of 

Labrador 

Current 

shifts 

northward. 

Shift in gyre 

positions.

Decreased 

dissolved 

oxygen. 

-0.004 mol 

m-3 by 2050 

(~1.0%). 

Greater 

likelihood of 

hypoxia.

RVA Species 

Affected (top 3 

climate 

impact)

8 of 11 7 of 11 5 of 11 3 of 11 3 of 11

Median 

Likelihood Likely Almost 

Certain Likely Possible Likely

Median 

Consequence Moderate Moderate Moderate Low Catastrophic

Median Risk High High High Moderate Extreme

Median 

Adaptive 

Capacity

High High High High High

Median 

Vulnerability Moderate Moderate Moderate Low Moderate
68

of this stressor was deemed “Almost Certain,” and when coupled with a moderate nonclimate consequence produced a high risk of impact.

Ocean acidification was identified as a major climate stressor for about half of the 

assessed species, with a likely chance of occurrence. As with storms and temperature, a 

moderate level of consequence yielded an overall high risk of impact.

Altered currents and associated declining dissolved oxygen were identified as primary 

climate stressors for three of the species assessed. Effects included diminished and 

shifted larval recruitment, reduced fecundity, and food source mismatches. Dissolved 

oxygen reduction was deemed likely, while altered currents were possible. Altered 

currents had a moderate risk due to low non-climate consequences, but declining 

dissolved oxygen would be greatly exacerbated by catastrophic level non-climate 

stressors on the affected species, resulting in extreme risk.

Throughout the assessments, the adaptive capacity, or the ability of the species to 

mitigate or adapt to the climate stress combined with the stewardship capacity of 

GRNMS and its partners that can be applied to manage species impacts, was identified as 

high. As a result, otherwise high vulnerability scores were lowered to moderate.

However, it should be noted that in nearly all instances, the final vulnerability scores 

were on the upper limit of the moderate range, and workshop participants felt that the 

three-tier ranking (low, moderate, high) somewhat underrepresented the true vulnerability 

of the species to the identified climate stressors. Participants suggested that future 

applications of this particular RVA tool would benefit from expanding the vulnerability 

index to five tiers (e.g., negligible, low, moderate, high, extreme) to more accurately 

convey assessment results.

One species that received attention in the workshop but was not individually assessed 

was the red lionfish (Pterois volitans). This species, invasive to Atlantic coastal waters 

since the 1990s, has been documented at GRNMS since at least 2003. Workshop 

participants identified lionfish as a non-climate stressor for many of the assessed species, 

as it is an opportunistic feeder that competes with many of the native foragers and 

predators for food, and reduces survivorship of native juveniles.

As a result, lionfish reduction efforts (e.g., traps, derbies) were frequently listed as 

potential adaptation strategies to lower species risk and vulnerability to climate change. 

While costs would likely be low, efficacy is uncertain as lionfish are prolific reproducers, 

have no well-established predators in the Atlantic, and are extremely adaptable to 

different habitats. Also, little is known about lionfish spawning locations/behaviors in the 

region. Additionally, although some success has been gained in local population 

reduction (e.g., culling, trapping, and removal from source locations outside MPA 

boundaries), evidence from removal efforts elsewhere (e.g., Florida, Cayman Islands) 

suggests that complete eradication may be impossible, advancing the questions of 
69

whether lionfish are likely to become a permanent fixture in the GRNMS habitat, and 

when (if ever) they should no longer be considered “invasive.”

Other frequently identified adaptation strategies to reduce species risk and vulnerability 

to climate changes were primarily centered about monitoring efforts. With the high 

number of species likely impacted by major storms, participants noted the lack of a poststorm assessment process for GRNMS. They suggested GRNMS could establish a 

protocol for visiting the sanctuary and surveying storm damage soon after the storm 

passed. This would be a low cost, high efficacy way to create a recovery baseline, 

monitor recovery progress, and target management efforts to those species that exhibited 

difficulty in rebounding. Additionally, a number of species adaptation strategies 

suggested improving long-term ecological and climate monitoring, either by increasing 

surveys or by establishing additional monitoring instrumentation. Increasing and pairing 

long-term monitoring and assessment surveys currently underway in GRNMS with poststorm event monitoring may help tease out species and habitat vulnerabilities from storm 

events.

Next steps

This report should not be considered as a “roadmap” to action. Rather it summarizes the 

workshop outcomes and provides a variety of possible adaptation strategies that GRNMS 

may consider in future management planning. The report is not intended to be a 

comprehensive source of information or a recommendation for advancing a particular 

course of action over others. The nature of the workshop encouraged participants to reach 

determinations in a limited amount of time and often with incomplete information, with 

an intent that the outcomes would reveal what is known, where information gaps exist, 

and what may require a more comprehensive examination.

The Rapid Vulnerability Assessment workshop at Gray’s Reef National Marine 

Sanctuary was the first full implementation of the CEC Rapid Vulnerability Assessment 

tool, and a pilot application for the Office of National Marine Sanctuaries to test the 

efficacy of the method. Workshop participants provided feedback to sanctuary staff 

following the workshop that will be incorporated for future application at additional 

national marine sanctuaries, but the overall response from participants was that the 

workshop was a good use of time and an effective way to approach climate-informed 

planning at the sanctuary. It is the hope of this assessment report that the conversation 

regarding climate vulnerability at Gray’s Reef will continue, and as resources, expertise, 

and information become available, additional species should be assessed and included in 

future editions of this report. To that end, participants identified the following species for 

future assessments:

1. Algal species (e.g., Sargassum) 

2. Invasive lionfish

3. Polychaetes (soft-bottom infaunal) 
70

a. Nereid worm

b. Glycerid worm

4. Belted sandfish (prey species that is tied to the reefs)

5. Tunicate (information lacking)

6. Lancelet (information lacking)

Immediate next steps identified for the sanctuary include engaging with the Sanctuary 

Advisory Council, including the Connectivity Working Group, around the results of this 

workshop and next steps for climate adaptation at the sanctuary; investing time and 

resources in completing a storm response plan for GRNMS resources to document 

damage following large, destructive storms; and prioritizing the gathering and analysis of 

visitation and use of the sanctuary to inform enforcement and education actions.

Additional discussion regarding collaborative adaptation actions occurred as the last item 

on the workshop agenda, and discussion centered on the following themes:

Education/outreach

Due to its importance to the recreational fishing community, there may be an opportunity 

to use the declining black sea bass population as a bellwether for climate change. These 

efforts could reach a constituency that has not traditionally been receptive to the concept 

of climate change. From an ecological standpoint, there are potential replacements, but 

many people, particularly recreational fishers, care about sea bass in particular. Climate 

impacts to sea bass distribution could provide a tangible, real-time example of climate 

change.

Lionfish

Pursue proactive management of lionfish. There are not many out there right now, but 

workshop participants agreed that it is a good idea to get ahead of the problem by 

introducing lionfish fishing (derbies) and trapping while local extirpation from with 

GRNMS may still be tenable. 

MPA connectivity 

Consider increasing the size of Gray’s Reef research area and of the sanctuary itself, with 

connected units within the region. For pelagic species, GRNMS may be too small to 

effect change. A network of connected MPAs is needed to effectively manage these 

species for climate change. The following ideas were presented to that effect: 

● Connect first with the South Atlantic Fishery Management Council (SAFMC) to 

discuss the expansion of the system of MPAs in the South Atlantic region.

● Identify deeper environments that serve as refuges to species for temperature and 

consider adding them to GRNMS.

● SAFMC MPAs and GRNMS are not showing much impact to building the 

fisheries, so it may be time to talk about what is needed in the region (may be due 

to remote location and less fishing effort than other MPAs). Seasonal changes 

make it more complicated as well.
71

● Currently SAFMC does not protect pelagic predators (only bottom species, by 

restricting bottom trawling). FMC MPAs should be based on the relationship 

between pelagic and benthic species based on research.

Post-storm analysis

GRNMS has a hurricane plan for the office, but not for the sanctuary to evaluate damage 

on sanctuary resources.

Enhanced collaboration

With king mackerel moving into other areas, enhancing collaboration with Stellwagen 

Bank National Marine Sanctuary and the Mid-Atlantic/New England FMCs on 

management of the species may be judicious.

Sanctuary visitation/use

Data have shown no difference between the research area (where no fishing is allowed) 

and the public-use area of the sanctuary; this could be due to regulations not being 

followed (in which case, increased enforcement of existing regulations is critical to 

mitigate local, non-climate effects such as anchor damage), or that the sanctuary is not 

being fished enough to detect a difference. Fishing activity within the research area has 

been documented (i.e., marine debris and boats with gear in the water). Data on visitation 

and use of the sanctuary are critical to understand if enforcement is needed. The 

remoteness of the site has to date precluded systematic monitoring of usage. Workshop 

participants had suggested possible technological solutions to capture sanctuary 

visitations. Some ideas include:

● Partnership with university to analyze satellite imagery data to do boat counts –

images still need to be processed.

● Citizen science project.

● Tech program to analyze images for boats automatically.

● Buoy hotspot that can be used to track boats.

The GRNMS Rapid Vulnerability Assessment workshop and report provided preliminary 

insight into the potential impact of select climate-driven and non-climate stressors on 

several key species present in the sanctuary. Inherent to a more “rapid” assessment 

approach, many factors and variables were not considered, but as the original RVA 

methodology states, the longer-term goal of applying this approach is to empower 

managers to “regularly consider the implications of climate change in their work, either 

by revisiting and reapplying the tool, or by applying the thought process it provides.”

This has been a positive first step toward identifying dominant climate and non-climate 

stressors affecting the sustainability of the sanctuary, and has promoted discussion about 

existing and potential measures to reduce exposure or enhance adaptation and resilience. 

In nearly all adaptation strategies, a regional approach in which the GRNMS is used as a 

sentinel site or in an evaluation role may provide more effectual solutions to addressing 

species and habitat vulnerability and adaptation. However, much more work is required 

to determine whether such measures are feasible or can be effective strategies for the 

sanctuary.
72

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78

Acknowledgements

The authors and editors of this report gratefully acknowledge the workshop participants 

without whose expertise this work would not have been possible. Also, we thank the staff 

of Gray’s Reef National Marine Sanctuary and the Skidaway Institute of Oceanography 

for accommodating the workshop, providing overnight accommodations, and making all 

the participants feel welcome. Furthermore, we are grateful to the National Marine 

Sanctuaries Foundation which bore a portion of the financial costs of hosting this 

workshop. Finally, we wish to acknowledge the time and effort of the Office of National 

Marine Sanctuaries and the three anonymous reviewers who have ensured that this report 

is of the highest quality.
79

Glossary of Acronyms

ACL Annual Catch Limit

AMO Atlantic Multidecadal Oscillation

AMPS Advanced Modular Payload System

AR5 Fifth IPCC Assessment Report

CaCO3 Calcium Carbonate

CEC Commission for Environmental Cooperation

CITES Convention on International Trade in Endangered Species of Wild Fauna 

and Flora

CMIP5 Fifth Coupled Model Intercomparison Project

CO2 Carbon Dioxide

DNR Department of Natural Resources

DO Dissolved Oxygen

DPS Distinct Population Segment

ERP Ecological Reference Point

FKNMS Florida Keys National Marine Sanctuary

FL Florida

GA Georgia

GRNMS Gray’s Reef National Marine Sanctuary

IBTrACS International Best Track Archive for Climate Stewardship

ICOADS International Comprehensive Ocean Atmosphere Data Set

IPCC Intergovernmental Panel on Climate Change

KNMI Koninklijk Nederlands Meteorologisch Instituut 

(Royal Netherlands Meteorological Institute)

MPA Marine Protected Area

NC North Carolina

NCEI National Centers for Environmental Information (NOAA)

NMFS National Marine Fisheries Service (NOAA)

NOAA National Oceanic and Atmospheric Administration

NWA Northwest Atlantic

NWLON National Water level Observing Network

OADS Ocean Acidification Data Stewardship

RCP Relative Concentration Pathway

RVA Rapid Vulnerability Assessment

SAFMC South Atlantic Fishery Management Council

SEFSC Southeast Fisheries Science Center

SkIO Skidaway Institute of Oceanography

USFWS United States Fish and Wildlife Service
80

Appendix A. Workshop Agenda

Gray’s Reef National Marine Sanctuary

Vulnerability Assessment Workshop

November 7-8, 2017

10 Ocean Science Circle

Savannah GA 31411

Thank you for participating in this 2-day workshop to assess the vulnerability of select 

Sanctuary resources to the impacts of climate change.

The objectives of this workshop are to:

1. Apply a rapid vulnerability assessment tool to selected species of GRNMS;

2. Allow managers and partners to engage with the science of climate change as it 

pertains to their climate concerns;

3. Encourage the creation of adaptation strategies to reduce the vulnerabilities that are 

identified through the assessment process; and

4. Provide education and networking opportunities to partners and stakeholders to 

increase knowledge and awareness of climate science and to enhance outreach related to 

climate change and its impacts in GRNMS.

Tuesday November 7

9:00 – 9:30 Sign-in and breakfast (provided by the National Marine Sanctuaries 

Foundation)

9:30 – 9:35 Welcome

George Sedberry, GRNMS

9:35 – 9:45 Participant Introductions

9:45 – 10:15 Introduction to Agenda and Workshop Objectives

Sara Hutto, GFNMS and Helene Scalliet, ONMS

10:15–10:30 Presentation: Climate Trends in the Region

Karsten Shein, NOAA
81

Tuesday November 7 (continued)

10:30–11:00 Presentation and Discussion: Tool Overview and Defining the Scope of the 

Assessments

Sara Hutto, GFNMS and George Sedberry, GRNMS

11:00 – 11:15 Break and re-assemble into break-out groups

11:15–12:30 Activity: Construct matrices and begin assessments for selected species

12:30–1:30 Lunch (provided by the National Marine Sanctuaries Foundation)

1:30–4:00 Activity: Complete assessments for selected species

4:00–5:00 Wrap-up Discussion:

What did we learn?

What issues did we encounter?

Planning Day Two

No-host group dinner – gather and depart at 6:00 for Savannah

Wednesday November 8

8:00-8:30 Breakfast (provided by the National Marine Sanctuaries Foundation)

8:30–8:45 Introduction to Day Two - goals and agenda

Sara Hutto, GFNMS

8:45–10:15 Activity: Complete assessments

10:15 – 10:30 Break

10:30 – 10:45 Presentation: Introduction to Adaptation Planning

Sara Hutto, GFNMS

10:45 – 12:15 Activity: Adaptation Strategy Development
82

Wednesday November 8 (continued)

12:15 – 1:00 Lunch (provided by the National Marine Sanctuaries Foundation)

1:00 – 2:00 Large group discussion: adaptation strategies

2:00 – 2:30 Wrap-up, Next Steps, Feedback

2:30 Workshop Adjournment
83

Appendix B. Participant List

Joseph Cavanaugh

Fisheries Ecology

NOAA National Marine Fisheries Service

Scott Noakes

Ocean Chemistry

University of Georgia

Mary Conley

Marine Conservation

The Nature Conservancy

Marcel Reichert

Fisheries

South Carolina Dept. of Natural Resources

Pat Geer

Marine Fisheries

Georgia Dept. of Natural Resources

Kim Roberson

Research Coordinator

Gray’s Reef National Marine Sanctuary

Danny Gleason

Invertebrate taxonomy/ecology

Georgia Southern University

Hélène Scalliet 

Program Specialist

NOAA Office of National Marine Sanctuaries

Justin Grubich

Marine Ecology

Pew Charitable Trusts

George Sedberry

Superintendent

Gray’s Reef National Marine Sanctuary

Chris Hines

Deputy Superintendent

Gray’s Reef National Marine Sanctuary

Karsten Shein

Climatologist

National Centers for Environmental Information

Sara Hutto

Climate Program Coordinator

Greater Farallones National Marine Sanctuary

Becky Shortland

Resource Protection / Facilitator

Gray’s Reef National Marine Sanctuary

David Lawrence

Ecologist

U.S. National Parks Service

Tracy Ziegler

Marine Ecology

U.S. National Parks Service

Roldan Muñoz

Fisheries Ecology

NOAA National Marine Fisheries Service
84

Appendix C. CEC North American Marine 

Protected Area Rapid Vulnerability Assessment 

Tool: Worksheets and Instructions

INSTRUCTIONS AND WORKSHEET PDFs can be viewed at: 

USER GUIDE: http://www3.cec.org/islandora/en/item/11733-north-american-marineprotected-area-rapid-vulnerability-assessment-tool-en.pdf

WORKSHEETS:

http://www3.cec.org/islandora/en/item/11739-north-american-marine-protected-arearapid-vulnerability-assessment-tool-en.pdf
1