Gray's Reef National Marine Sanctuary
2008 Condition Report

#	Status	Rating	Basis For Judgement	Description of Findings
5.	Abundance/ Distribution	?	Baseline data recently completed; assessment of trends will depend on future observations	Selected habitat loss or alteration has taken place, precluding full development of living resource assemblages, but it is unlikely to cause substantial or persistent degradation in living resources or water quality.
6.	Structure	?	Insufficient information on the complex biological structure of habitats to rate condition, though there is evidence of anchor, fishing, and storm damage	N/A
7.	Contaminants		Low levels in 2000 and 2005	Contaminants do not appear to have the potential to negatively affect living resources or water quality.
8.	Human Activities	?	Localized within areas of heavy use	Selected activities have resulted in meaurable habitat impacts, but evidence suggests effects are localized, not widespread.

Living Resources

Fishes

The highest fish species richness, diversity, abundance and biomass at Gray’s Reef National Marine Sanctuary is found on and near reef structure (‘live bottom’). Resident and non resident reef fishes normally associate with hard structure, and even coastal migratory pelagic species such as mackerels are attracted to and orient themselves near structures. Flat and rippled sand sites have the lowest value in fish species richness, diversity, abundance and biomass. Analysis of fish assemblages at ledges (high-relief hard structure areas) indicates that species richness and total abundance of fish are positively related to total percent cover of sessile invertebrates and ledge height (Kendall et al. 2007). As a result, ledges within the sanctuary are often targeted by fishermen due to the association of recreationally important fish species with this bottom type and because ledges are structurally complex and are often densely colonized by biota. In addition, pelagic predators like king mackerel feed on schools of pelagic baitfish that concentrate down current from bottom structure.

Currently, recreational fishing pressure on reef-associated fishes is thought to be less intense than it is for pelagic species, although studies conducted at the Gray’s Reef sanctuary indicate that fishing mortality for black sea bass is the same or higher within the sanctuary than it is regionally or at inner-shelf reefs off South Carolina (Harris et al. 2005). The most intensive fishing pressure occurs in conjunction with offshore fishing tournaments, which target king mackerel. Weekends experience more fishing activity than weekdays. On an annual basis, fishing pressure is patterned around meteorological events and migratory patterns of the targeted species. Fishing pressure is probably lowest in mid-winter with low temperatures and winter storms. By late winter or early spring, recreational fishing pressure increases as the anglers target black sea bass. In late spring to early summer, fishing pressure peaks as anglers target the pelagic cobia, bluefish, Spanish mackerel and king mackerel. Late summer experiences a slump in fishing pressure as target species are widely scattered and difficult to catch. By fall, fishing pressure increases again as the pelagic species return. This is sustained until the water temperature drops low enough to cause the target species to migrate out of the area.

In 1993, NOAA’s National Marine Fisheries Service’s Marine Resources Monitoring Assessment and Prediction Program established sampling stations at Gray’s Reef sanctuary to monitor reef fish populations. During the trapping periods (July 1993-1995 and July 1998-2001), catches were dominated by black sea bass (50 percent), followed by scup (34 percent) and tomtate (12 percent). Other species caught included pinfish, blue runner, gray triggerfish, northern puffer and leopard toadfish.

In the Gray’s Reef sanctuary, the number of black sea bass caught per trap has increased since 1993, with a significant increase occurring in 2000 (Figure 24). Estimated abundance of black sea bass at the sanctuary showed a large increase from 1993 to 2001, followed by a decrease through 2004. Due in part to a high year of larval recruitment, the population size estimate increased in 2005, and is the second highest estimate since 1993. This species, like many in the snapper-grouper complex, resides on reefs and other structures as adults. Black sea bass are estuarine-dependent as juveniles, and relatively little is known about their spawning behaviors in or near the sanctuary. Tagging data indicated that after three months, 93 percent of the fish were recaptured at Gray’s Reef, suggesting that these fishes show relatively low rates of movement. Tags returns from recreational fishermen outside the boundaries indicate that many of the larger fish move out of the sanctuary (Harris et al. 2004, McGovern et al. 2002).

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

Diversity at Gray’s Reef National Marine Sanctuary is very high compared to shelf sites at similar depths north of Cape Hatteras, but there are no baseline data to determine if diversity has changed in response to fishing pressure exerted since the 1970s.

There is considerable benthic, epifauna and fish biodiversity monitoring and data, but data is insufficient at this time to rate the status of the resources and impacts on full community development and function. Benthic infaunal invertebrate diversity in the Gray’s Reef sanctuary is very high, and is higher than comparable depths off mid-Atlantic and northeastern states. The complexity of these structures, however, is not completely understood, and there are no baseline data (i.e., pre-fishing years) to compare with present diversity measures. Diversity of benthic infauna did not change from one study in 2000 (after at least 30 years of commercial and recreational fishing) to a follow-up in 2005 (Cooksey et al. 2004, Hyland et al. 2006). Samples collected had a mean diversity of 45 (+ 11) species per grab (0.04 m2) in 2000 and 47 (+ 12) in 2005. The total number of infauna collected was about 350 taxa. Benthic infauna are an important food source for forage fishes and some fishery species and are an important link in the food chain.

Fish diversity is also quite high in the sanctuary, with 181 species recorded, including 46 managed species (Hare et al. in press). Annual monitoring by visual census has indicated no change in fish diversity (REEF, unpublished). The Gray’s Reef sanctuary is in a transitional zone between cold temperate and warm temperate waters. Because of this, the fish community likely changes considerably in response to episodic hydrographic events like cold water intrusions and Gulf Stream eddies, and may be in a constant state of succession toward full community development.

10. What is the status of environmentally sustainable fishing and how is it changing?

Regional fishing has caused or is likely to cause severe declines in some but not all ecosystem components at Gray’s Reef and reduce ecosystem integrity. Furthermore, this condition appears to be getting worse. According to NOAA’s National Marine Fisheries Service (2006), red snapper, gag, red grouper and black sea bass are overfished. Gray triggerfish, sheepshead and greater amberjack are not currently overfished in the region.

Monitoring of the abundance and size of black sea bass (the dominant reef-associated fishery species at the sanctuary) in trap surveys indicates trends in abundance and size that are similar to trends found throughout the region, where this species is classified as overfished and is undergoing overfishing. This may indicate that federal region-wide fishery management measures have a greater influence on status of stock than do sanctuary regulations. Tagging studies of black sea bass indicate high rates of tag returns from recreational fishermen, resulting from high fishing effort within the sanctuary. Tagging and catch curve analysis from trap survey catches indicate that fishing mortality of black sea bass at the Gray’s Reef sanctuary is as high as or higher than that on other reefs throughout the region. Mean length of black sea bass in trap surveys at the sanctuary has increased since 1993, following similar trends throughout the region, and is likely influenced by increases in minimum size imposed by the South Atlantic Fishery Management Council (Harris et al. 2005). There is good and consistent annual recruitment of small black sea bass in trap catches.

Gag and scamp have decreased in abundance in visual census transects, and length-frequency measurements of black sea bass, gag and scamp (from trap and visual census data) indicate that a large portion of the population is removed upon reaching minimum size, either by fishing or by migration out of the sanctuary.

There is considerable but unmeasured fishing effort on coastal pelagic species (king and Spanish mackerel) during mackerel tournaments and at other times. Federal management of coastal pelagic species has resulted in sustainable fisheries for king mackerel and the stock is not currently overfished.

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

The status of non-indigenous species in the sanctuary is considered to be “good/fair” — non-indigenous species exist, precluding full community development and function, but are unlikely to cause substantial or persistent degradation of ecosystem integrity. This trend is declining. Two species of red lionfish (Pterois volitans and P. miles), formerly residents of the western Pacific and eastern Indian oceans only, have become well established in the western Atlantic along the eastern coast of the U.S. (Whitfield et al. 2002) and have been documented at sites in close proximity to the Gray’s Reef sanctuary boundaries. In fall 2007, NOAA’s National Centers for Coastal Ocean Science reported the first sighting of two red lionfish in the sanctuary (Figure 25). Because very few physical characteristics distinguish the two species of red lionfish it is unknown which species was actually sighted. The range and abundance of this species is continuing to increase (Ruiz-Carus 2006). In January 2008, three barnacles of the invasive species Megabalanus coccopoma (titan acorn barnacle) were found in Gray’s Reef attached to the data buoy. These barnacles, native to the western Pacific, have been found throughout the southeast Atlantic. Potential impacts of these and other organisms include competition with native species for food and space, predation on native species, and diseases to which native species have no resistance (Ruiz-Carus 2006). Impacts from red lionfish could include direct competition with large groupers (Mycteroperca spp.) for food and predation on smaller sea basses (Serranidae spp.) and other benthic fish and crustaceans (Ruiz-Carus 2006). Potential human impacts could result from fishers or divers coming in contact with venomous spines. Impacts from titan barnacles could include spatial dominance of available habitat. Titan acorn barnacles could exclude other epifaunal species, including local barnacles, mussels, oysters, corals and sponges. Cold seasonal water temperatures could hinder year-round establishment of red lionfish (Kimball et al. 2004) and titan acorn barnacles.

12. What is the status of key species and how is it changing?

The status of key species in the sanctuary is considered to be fair, as selected key species are at reduced levels, but recovery is possible. The condition, however, may be getting worse. Key species of fishes in the sanctuary include gag and scamp, king mackerel, black sea bass and red snapper, all of which are targeted by fishers and are dominant predators in the ecosystem. While gag and scamp can be found at the sanctuary, they are not found in the numbers that might be anticipated based on the abundance of suitable habitat and available resources. Of the 92 ledges surveyed by Kendall et al. (2007), only 20 had occurrences of these species, with the majority of the species occurring on just 10 ledges. The spatial distribution of bothspecies was quite clumped on ledges in the north central and south central regions of the sanctuary. In addition, both species were often observed together at the same ledge and were rarely observed as lone individuals. In contrast, black sea bassoccurred at 98 percent of the ledges surveyed and appeared evenly distributed through-out the sanctuary. Pressure on king mackerel has been steadily increasing at Gray’s Reef in the recent past, with the majority of effort coming from fishing tournaments.

Benthic cover of invertebrates on live-bottom areas in the sanctuary is dominated by various species of sponges (primarily in the genera Ircinia and Chondrilla), corals (predominately Oculina arbuscula), tunicates (including Styela, Aplidium andSymplegma), arborescent bryozoans (primarily Schizoporella) and gorgonians (dominated by Telesto and Leptogorgia) (Ruzicka 2005, Gleason et al. 2007). No evidence of disease has been observed on these key benthic species, although recent mortalities in Ircinia seem to correlate with warmer water temperatures. Recently established long-term monitoring of the benthos has noted some decline in percent cover and species diversity, but these changes appear to be due to storm impacts (i.e., movement of sediment) or represent seasonal cycles (Freeman et al. 2007).

According to NMFS (2008) and SEDAR (2008) , red snapper, gag, red grouper and black sea bass are overfished and/or undergoing overfishing throughout the region. Tagging studies of black sea bass indicate high rates of tag returns from recreational fishermen, resulting from high fishing effort within the sanctuary. Tagging and catch curve analysis from trap survey catches indicate that fishing mortality for black sea bass at the Gray’s Reef sanctuary is as high as or higher than that on other reefs throughout the region. Mean length of black sea bass in trap surveys at the sanctuary has increased since 1993, following similar trends throughout the region, and is likely influenced by increases in minimum size imposed by the South Atlantic Fishery Management Council (Harris et al. 2005). There is good and consistent annual recruitment of small black sea bass in trap catches.

Based on the above information, the status of key species is determined to be fair and the trend appears to be decreasing.

13. What is the condition or health of key species and how is it changing?

The condition of key species at the Gray’s Reef sanctuary has not been systematically assessed, nor have trends been identified. Sponges, recognized as key species at Gray’s Reef due to their importance in structuring habitat, however, have been found to contain organic contaminants (PCBs, PAHs etc.) in their tissues. These filtering organisms appear to be accumulating contaminants from the water column (McFall pers. comm.). Tissues from mussels and fish and sediments have been used recently to determine the level of contaminants in the sanctuary (Cooksey et al. 2004, Hyland at al. 2006), but the amounts present in the sponge tissues appear to be higher than levels reported from these other sources. Coral has also been identified as a key species at Gray’s Reef, with the most prominent species being Oculina arbuscula. This species shows high recruitment rates (Gleason in prep.) and genetic studies indicate that new individuals result from “local” recruitment (Wagner 2006),reflecting a reproductively healthy O. arbusculapopulation in the sanctuary. Insufficient data exist to determine a trend.

14. What are the levels of human activities that may influence living resource quality and how are they changing?

Certain human activities have resulted in measurable living resource impacts, but evidence suggests effects are localized and not widespread. The trend, however, is undetermined. Activities that are most likely to affect living resources at Gray’s Reef are recreational bottom fishing (from boats and perhaps spearfishing), diving (recreational and research), certain research activities (e.g., collecting, coring, data collection), anchoring, disposal of marine debris, and coastal development. Observational data suggest that the activity having the most measurable effect on living resources is recreational bottom fishing. Aside from creating some of the marine debris at Gray’s Reef, fishing appears to depress the size-frequency distribution for black sea bass, potentially affecting their abundance, fecundity and availability as food for other species. Additional information exists to show a regional trend for other species, such as gag and scamp, as well. Existing data suggest that approximately 20 percent of fishers at Gray’s Reef participate in bottom fishing, but time-series data that might be used for assessing trends are not currently available.

Diver impacts, whether they result from research, recreation or spearfishing, are intermittent and generally limited to specific study locations. Similarly, anchoring and marine debris are concentrated in locations with high visitation, and most impacts have been observed in areas with the highest relief and cover. Of the marine debris surveyed at Gray’s Reef, two-thirds is composed of fishing line (usually entangled), which, like other visitation-related activities, is most heavily concentrated in areas of high relief. Data on levels for most of these activities, and for any impacts they might be causing, are generally lacking, as are data on trends.

Preliminary data from one on-going study suggest that evidence of accumulation of certain organic contaminants in sponges likely results from coastal development, but it is not known whether these are at high enough levels to be of concern. Coastal development is certain to continue to increase, making this an activity that should be monitored closely.

The following information provides an assessment by sanctuary staff and the Gray’s Reef Research Advisory Panel of the status and trends pertaining to the current state of the sanctuary’s living resources:

Living Resources and Trends

Status:   Good     Good/Fair      Fair      Fair/Poor      Poor       Undet.  

Trends:

▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.

#	Status	Rating	Basis For Judgement	Description of Findings
9.	Biodiversity	?	Considerable benthic, epifauna and fish biodiversity monitoring and data, but insufficient at this time to rate status, trends and impacts as they relate to community development and function	N/A
10.	Extracted Species		Black sea bass, gag, red grouper, and red snapper regionally overfished and/or undergoing overfishing	Extraction has caused or is likely to cause severe declines in some but not all ecosystem components and reduce ecosystem integrity.
11.	Non-indigenous Species		Two lionfish identified in sanctuary in fall 2007	Non-indigenous species exist, precluding full community development and function, but are unlikely to cause substantial or persistent degradation of ecosystem integrity.
12.	Key Species Status		Removal of key fish species and recent sponge mortality	The reduced abundance of selected key species may inhibit full community development and function, and may cause measurable but not severe degradation of ecosystem integrity; or selected key species are at reduced levels, but recovery is possible.
13.	Key Species Condition	?	Key species tentatively identified but unable to determine condition and health; some contaminants detected in sponges, but cause of mortality undetermined	N/A
14.	Human Activities	?	Localized within areas of heavy use	Selected activities have resulted in measurable living resource impacts, but evidence suggests effects are localized, not widespread.

Maritime Archaeological Resources

There are currently no known shipwrecks in the sanctuary, but Gray’s Reef National Marine Sanctuary does contain considerable paleontological resources of both marine and terrestrial origin. This may have important implications with regard to former human occupation of the area, and the potential for future archaeological finds.

Within the sanctuary boundaries, two research stations have been well documented to contain large areas of ancient scallop (Placopecten magellanicus) beds. These scallops have been dated to approximately 42,000 to 44,000 years before present and range in size up to 20 centimeters in diameter. In addition to the two research stations, the scallops have also been documented at several other sites throughout the sanctuary.

The primary importance of the ancient scallop beds is that they shed some light on past climate change at Gray’s Reef. The presence of these scallops dictates a much colder environment than what is currently found at Gray’s Reef today. The death assemblage also indicates a potentially rapid rise in the ocean temperature at Gray’s Reef that makes the shells proxies for the timing and rate of climate shifts. In the scientific community today, there is great interest in accurate hindcasts for Earth’s climate that provide real context by which to measure and assess modern climate change. These resources may provide a significant role in understanding future climate change, which makes it a vital task to preserve and monitor these “maritime archaeological, paleontological and prehistoric resources” in the sanctuary, as set forth in the enabling legislation of the National Marine Sanctuary System.

Also frequently discovered at the sanctuary are fossilized terrestrial and marine mammal bone fragments. These bone fragments help to piece together the changes at Gray’s Reef as Georgia’s shoreline advanced and retreated over geologic time. It has been well documented that Gray’s Reef was last exposed approximately 7,000 years ago and prior to that had been submerged and exposed many times, allowing both marine and terrestrial animals to live there.

A recent discovery near Gray’s Reef, dated by radiocarbon methods to 38,000 years ago, is that of a northern right whale (Eubalaena glacialis) cranial bone. This discovery alone suggests that the Georgia Bight was a favored ground for this endangered species long before the modern era.

To date, only a few manmade prehistoric artifacts have been recovered at Gray’s Reef. These artifacts have been points of interest and discussion over the years, but no archaeological sites have been discovered in association with these finds. However, since Gray’s Reef was last exposed approximately 7,000 years ago, it is possible that humans once lived and hunted in the area before submergence in post-glacial time (Holocene). It thus remains a possibility that important undiscovered archaeological evidence exists at Gray’s Reef.

Natural oceanographic forces pose the main danger to the Gray’s Reef sanctuary’s prehistoric, archaeological and paleontological resources. Erosion due to storms and natural currents continuously occurs at the bottom, as moving sand exposes and buries the scallop beds and bone fragments. Little can be done to prevent damage to sanctuary resources from these forces except monitor the sites and recover and document any finds as they become exposed. Recreational diving and anchoring at the sanctuary could potentially impact the resources, but since anchoring has been banned within the sanctuary, it is not expected that this will be a major problem.

The following information provides an assessment by sanctuary staff and the Gray’s Reef Research Advisory Panel of the status and trends pertaining to the current state of the sanctuary’s maritime archaeological resources:

Maritime Archaeological Resources and Trends

Status:   Good     Good/Fair      Fair      Fair/Poor      Poor       Undet.  

Trends:

▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.

#	Status	Rating	Basis For Judgement	Description of Findings
15.	Integrity	N/A	No archaeological evidence, though former human occupation remains a possibility based on paleontological data	N/A
16.	Threat to Environment	N/A	No archaeological evidence, though former human occupation remains a possibility based on paleontological data	N/A
17.	Human Activities		Potential for diving, fishing and anchoring to damage sites	Some potentially relevant activites exist, but they do not appear to have had a negative effect on maritime archaeological resource integrity.