Marine Sanctuaries Conservation Series ONMS-11-03

U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Ocean Service

Office of Ocean and Coastal Resource Management

Office of National Marine Sanctuaries July 2011

Fish and Habitat Community Assessments 

on North Carolina Shipwrecks:

Potential sites for detecting climate change

in the Graveyard of the Atlantic
About the Marine Sanctuaries Conservation Series

The National Oceanic and Atmospheric Administration’s National Ocean Service (NOS) 

administers the Office of National Marine Sanctuaries (ONMS). Its mission is to identify, 

designate, protect and manage the ecological, recreational, research, educational, 

historical, and aesthetic resources and qualities of nationally significant coastal and 

marine areas. The existing marine sanctuaries differ widely in their natural and 

historical resources and include nearshore and open ocean areas ranging in size from 

less than one to over 5,000 square miles. Protected habitats include rocky coasts, kelp 

forests, coral reefs, sea grass beds, estuarine habitats, hard and soft bottom habitats, 

segments of whale migration routes, and shipwrecks.

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 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 Web site 

(http://www.sanctuaries.noaa.gov).
Fish and Habitat Community Assessments 

on North Carolina Shipwrecks: 

Potential sites for detecting climate change in the 

Graveyard of the Atlantic

Paula E. Whitfield1

Roldan C. Muñoz2

Christine A. Buckel1

Lauren M. Heesemann3

1

NOAA, NOS, NCCOS, Center for Coastal Fisheries and Habitat Research

2

NOAA, NMFS, SEFSC, Beaufort Laboratory

3

NOAA, NOS, ONMS, Monitor National Marine Sanctuary

U.S. Department of Commerce

John Bryson, Secretary

National Ocean and Atmospheric Administration

Jane Lubchenco, Ph.D.

Under Secretary of Commerce for Oceans and Atmosphere

National Ocean Service

David M. Kennedy, Assistant Administrator

Office of National Marine Sanctuaries

Daniel J. Basta
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 web site at http://sanctuaries.noaa.gov. Hard copies may be available from 

the following address:

National Oceanic and Atmospheric Administration

Office of National Marine Sanctuaries

SSMC4, N/ORM62

1305 East-West Highway

Silver Spring, MD 20910

Cover

Cover photo by Doug Kesling Cooperative Institute for Ocean Exploration and 

Technology (CIOERT) shows the diverse benthic invertebrate community on the 

shipwreck, City of Atlanta, located north of Cape Hatteras, NC in the Graveyard of the 

Atlantic. 

Suggested Citation

Whitfield, P.E. Muñoz, R.C. Buckel, C.A., Heesemann, L.M. 2011. Fish Community and 

Habitat Assessments on North Carolina Shipwrecks: Monitor National Marine Sanctuary, 

Battle of the Atlantic, June 2010 Marine Sanctuaries Conservation Series ONMS-11-03. 

U.S. Department of Commerce, National Oceanic and Atmospheric Administration, 

Office of National Marine Sanctuaries, Silver Spring, MD. 39pp. 

Contact

Paula Whitfield

Research Ecologist

NOAA NOS Center for Coastal Fisheries and Habitat Research

101 Pivers Island Rd

Beaufort NC 28516

252 728-8714

paula.whitfield@noaa.gov
i

Abstract

The Monitor National Marine Sanctuary (MNMS) was the nation’s first sanctuary, 

originally established in 1975 to protect the famous civil war ironclad shipwreck, the 

USS Monitor. Since 2008, sanctuary sponsored archeological research has branched out 

to include historically significant U-boats and World War II shipwrecks within the larger 

Graveyard of the Atlantic off the coast of North Carolina. These shipwrecks are not only 

important for their cultural value, but also as habitat for a wide diversity of fishes, 

invertebrates and algal species. Additionally, due to their unique location within an 

important area for biological productivity, the sanctuary and other culturally valuable 

shipwrecks within the Graveyard of the Atlantic are potential sites for examining 

community change. For this reason, from June 8-30, 2010, biological and ecological 

investigations were conducted at four World War II shipwrecks (Keshena, City of 

Atlanta, Dixie Arrow, EM Clark), as part of the MNMS 2010 Battle of the Atlantic 

(BOTA) research project. At each shipwreck site, fish community surveys were 

conducted and benthic photo-quadrats were collected to characterize the mobile 

conspicuous fish, smaller prey fish, and sessile invertebrate and algal communities. In 

addition, temperature sensors were placed at all four shipwrecks previously mentioned, as 

well as an additional shipwreck, the Manuela. The data, which establishes a baseline 

condition to use in future assessments, suggest strong differences in both the fish and 

benthic communities among the surveyed shipwrecks based on the oceanographic zone 

(depth). In order to establish these shipwrecks as sites for detecting community change it 

is suggested that a subset of locations across the shelf be selected and repeatedly sampled 

over time. In order to reduce variability within sites for both the benthic and fish 

communities, a significant number of surveys should be conducted at each location. This 

sampling strategy will account for the natural differences in community structure that 

exist across the shelf due to the oceanographic regime, and allow robust statistical 

analyses of community differences over time. 

Key Words

Shipwrecks, Fish Community, Habitat, North Carolina, Climate, Baseline Data, 

Graveyard of the Atlantic, Benthic
ii

Table of Contents

Topic Page

Abstract................................................................................................................................ i

Key Words........................................................................................................................... i

Table of Contents................................................................................................................ ii

List of Figures and Tables..................................................................................................iii

Statement of Need............................................................................................................... 1

Methods............................................................................................................................... 4

Fish Community Assessments........................................................................................ 6

Benthic Habitat Assessments.......................................................................................... 7

Results................................................................................................................................. 9

Fish Community Assessments........................................................................................ 9

Benthic Habitat Assessments........................................................................................ 23

Discussion/Future Recommendations............................................................................... 29

Appendix........................................................................................................................... 32

Acknowledgments............................................................................................................. 35

Literature Cited ................................................................................................................. 36
iii

List of Figures and Tables

Figure/Table Number and Title Page

Figure 1. Map of shipwreck locations visited during BOTA 2010 expedition. (Map 

created by Paula Whitfield) ................................................................................................ 5

Figure 2. Examples of analyzed benthic habitat quadrats from each of the sites surveyed. 

Yellow box (25 x 25cm) delineates the analysis area of each image where 50 points are 

overlaid and classified to the finest taxonomic level possible............................................ 8

Figure 3. Total number of A) conspicuous fishes and B) prey fishes for all sites............ 10

Figure 4. Biomass for A) conspicuous fishes for all sites and B) prey fishes for all sites.11

Figure 5. Densities of conspicuous fishes for the A) Keshena and B) the City of Atlanta.

........................................................................................................................................... 12

Figure 6. Densities of conspicuous and prey fishes for the A) B) EM Clark and the C) D) 

Dixie Arrow....................................................................................................................... 13

Figure 7. Multi-dimensional plot of the conspicuous fish community at all sites with 10% 

similarity contour overlaid................................................................................................ 14

Figure 8. Size class graphs of conspicuous fishes representing the top six species in 

biomass. ............................................................................................................................ 16

Figure 9. Size class graphs of conspicuous fishes representing the top seven to 12 species 

in biomass. ........................................................................................................................ 17

Figure 10. Size class graphs of conspicuous fishes representing the top 13 to 18 species in 

biomass. ............................................................................................................................ 18

Figure 11. Size class graphs of conspicuous fish species representing the top 19 to 24 

species in biomass............................................................................................................. 19

Figure 12. Size class graphs of conspicuous fishes representing the last 25 to 32 species 

in biomass. ........................................................................................................................ 20

Figure 13. Size classes for prey fishes representing the top six species in prey fish 

biomass. ............................................................................................................................ 21
iv

Figure 14. Size classes for prey fishes representing the last seven to nine species in prey 

fish biomass. ..................................................................................................................... 22

Figure 15. Photo of the diverse invertebrate community on the EM Clark (72m) with 

schooling red barbier (Hemanthias vivanus). Photo credit: Doug Kesling (CIOERT) .... 23

Figure 16. Multi-dimensional plot of benthic habitat percent cover data for each site with 

the 40% similarity contour overlaid to illustrate site differences. .................................... 24

Figure 17. Percent cover by major benthic habitat category at all sites. .......................... 28

Table 1. Shipwrecks where biological surveys were conducted and/or where temperature 

sensors were placed during the 2010 Battle of the Atlantic expedition. This table does not 

include the Empire Gem or Monitor where only archaeological surveys were conducted. 

Vis. is abbreviated for visibility n* = number of transect conducted at a site.................... 5

Table 2. Diversity indices for conspicuous species by site............................................... 15

Table 3. Average dissimilarities between sites and percent contributions to the average 

dissimilarities of individual benthic habitat components are reported. Results of 

SIMPER, listed are species composing top 70% dissimilarity. ........................................ 25

Table 4. Mean percent cover of major benthic habitat groupings from all sites surveyed.

........................................................................................................................................... 27

Appendix A. Comprehensive fish species list. ................................................................. 32

Appendix B. Comprehensive benthic habitat group and species list................................ 34
1

Statement of Need

Background

The Monitor National Marine Sanctuary (MNMS) was the nation’s first sanctuary, 

originally established in 1975 to protect and preserve the remains of the famed Civil War 

ironclad shipwreck, USS Monitor. Since 1977, research at the Monitor site has been 

directed toward documenting this important maritime heritage resource in detail and 

understanding how it has been affected by natural deterioration and human activities.

More recently, the MNMS has conducted projects in and adjacent to the sanctuary in 

order to better understand and monitor the larger area’s living and non-living resources, 

and to increase knowledge of the sanctuary’s biological and cultural resources through 

research. The Monitor is located in an area known as the Graveyard of the Atlantic which 

also contains the final resting place of thousands of vessels lost to war, weather, or to the 

shallow sand shoals that extend off the North Carolina coast (Figure 1).

In 2008, the Monitor National Marine Sanctuary, in conjunction with the Office of 

National Marine Sanctuaries Maritime Heritage Program, initiated a multi-year study to 

examine the Battle of the Atlantic (BOTA) that took place during World War II. The fact 

that German U-boats and thus World War II came so close to the Eastern Seaboard is not 

commonly known by the general public. To better elucidate these historic events, 

determine the current state of these vessels, and monitor changes over time, 

archaeological surveys and documentation of shipwrecks lost during this event were 

initiated. To begin the project, the remains of three German U-boats (U-85, U-701, and 

U-352) were archaeologically surveyed in 2008. In 2009 and 2010 allied military and 

merchant vessel casualties were examined (see Hoyt 2010). It was during the 2010 

mission that ecological and biological surveys were conducted in conjunction and 

secondary to these archeological investigations. The shipwrecks surveyed during the 

project were chosen based on their historical significance during the Battle of the Atlantic 

in World War II. The Monitor was not specifically surveyed during this mission. 

Site Description

The shipwrecks surveyed during the 2011 BOTA mission (Keshena, Dixie Arrow, EM 

Clark, City of Atlanta) are positioned near Cape Hatteras, North Carolina, a natural 

zoogeographic break formed by the presence of the tropical Gulf Stream current flowing 

northward and the temperate Virginia and Labrador currents flowing southward (Briggs 

1974). The area between Cape Hatteras, North Carolina and Cape Canaveral, Florida is 

commonly called the South Atlantic Bight (SAB) and contains three recognized 

oceanographic zones across the continental shelf. These zones are identified as the inner 

shelf (0-20m water depth), middle shelf (20-40m), and outer shelf (40-60m) (Atkinson et 

al. 1983, Yoder 1991). The inner shelf water temperatures are controlled by and similar 

to the ambient air temperature, and therefore, the biological community is influenced by 

bottom water temperatures that can be less than 10° C in the winter. While the middle 
2

shelf and outer shelf waters are often moderated by the Gulf Stream, bottom water 

temperatures, especially in water depths greater than 60m, can often be difficult to predict 

because of deep water upwelling that draws cooler, deeper waters onto the shelf.

The shipwrecks surveyed were all sunk in 1942, within six months of each other. At the 

time of the biological surveys, each vessel had been underwater for approximately 68 

years (Figure 1):

City of Atlanta: 378 ft. in length, steam merchant vessel, sunk January 19, 1942 north of 

Diamond Shoals in 28 meters of water. Due to her location approximately 18 miles north 

of Diamond Shoals (middle shelf), the prevailing currents and bottom water temperatures 

are generally much more temperate and less tropical than locations south of the shoals. 

This is the northern most shipwreck surveyed during this study (Figure 1) (Gentile 1993).

Dixie Arrow: 485 ft. in length, tanker, sunk March 26, 1942 (Gentile 1992). Located 

approximately 23 miles southwest of Diamond Shoals in 28 meters of water (middle 

shelf). Dixie Arrow and the Keshena are within 5 miles of each other on the middle shelf 

in Raleigh Bay (Figure 1). The Dixie Arrow and the Keshena are likely to have warm 

conditions in the summer due to minimal upwelling effect that is present in deeper waters 

and to have cold conditions during the winter as there is less thermal influence of the 

Gulf Stream at both these sites (Yoder 1991, Atkinson et al. 1983). 

EM Clark: 499 ft. in length, tanker, sunk March 18, 1942 (Gentile 1992). Located 

approximately 20 miles south of Diamond Shoals in 72 feet of water (deeper than outer 

shelf). Due to the depth, this site generally experiences variably colder water 

temperatures in the summer during cold water upwelling events (Yoder 1991, Atkinson et 

al. 1983) but remains thermally moderated due to Gulf Stream proximity during the 

winter. 

Keshena: 142 ft. in length, tugboat, sunk July 19, 1942 (Gentile 1992). Located 

approximately 20 miles southwest of Diamond Shoals in 28 meters of water (middle 

shelf). Dixie Arrow and the Keshena are within 5 miles of each other on the middle shelf 

in Raleigh Bay (Figure 1).

Natural temperature fluctuations that occur across the shelf can strongly influence the 

types of marine communities (invertebrates, fishes, algae) that are found across the shelf 

(Wenner et al. 1983, Peckol and Searles 1984, Sedberry and Van Dolah 1984, Schobernd 

and Sedberry 2009). The vertical relief of the seafloor habitats has also been shown to 

influence fish community structure. Fish, sessile invertebrate, and algal abundance and 

diversity are found to be higher on elevated relief and structurally complex habitats 

(Hixon and Beets 1989, Lindquist et al. 1989, Kendall et al. 2007, Kendall et al. 2009, 

Schobernd and Sedberry 2009). It is thought that higher relief natural hardbottom habitat 

provides a more stable environment that is less susceptible to disturbance events such as 

sand abrasion, which can occur during large storms (Renaud et al. 1997). 
3

Due to their high relief and structural complexity, shipwrecks, also called artificial reefs, 

provide habitat, for many species of mobile fish and invertebrates as well as hard 

substrate for a variety of attached benthic invertebrates and algal species. (Hixon and 

Beets 1989, Lindquist et al. 1989, Carr and Hixon 1997, Moura et al. 2007). For decades, 

artificial reefs have been used as a management tool to increase fisheries yield, restore 

degraded habitats, and meet conservation objectives (Christian et al. 1998, Seaman 

2007). In coastal North Carolina, local economies have come to depend on the tourism 

income from divers and anglers who are attracted to the local shipwrecks as sources of 

recreation. Because shipwrecks function as important habitat, they can be studied along 

with natural reefs to better understand how climate change and other stressors (e.g.,

overfishing, invasive species) may impact marine communities. More importantly, the 

shipwrecks off North Carolina may be uniquely suited to this type of study due to their 

location within a natural zoogeographic transition zone. (Briggs 1974). Due to this 

transition zone, North Carolina waters are host to both temperate and tropical species of 

fishes and invertebrates (Whitfield et al. unpubl. data). However, in recent years, at a 

hardbottom site off North Carolina, Parker and Dixon (1998) found a community shift to 

a more tropical fauna. This study suggested that a 1° C increase in minimum winter 

bottom water temperatures may have caused the shift. In addition, during a five year 

study of the algal communities within natural temperate reefs off North Carolina, 

researchers found up to four tropical algae species never before documented in this area 

(Freshwater et al. unpubl. data). Combined, these data suggest that a transition to a more 

tropical community is already underway off North Carolina. While the shipwrecks within 

this study were chosen for their archaeological importance, they could also be used as 

sites for detecting community changes and could support existing data from natural 

hardbottom sites that have been collected for the past 5 years. Thus, the primary impetus 

for this work is to elucidate the ecological importance of these shipwrecks by collecting 

baseline community data and to use the initial data to improve future sampling designs 

that will increase the ability to detect future community shifts.

Goals and Objectives

Baseline biological and ecological assessments were conducted as part of the 2010

Monitor National Marine Sanctuary Battle of the Atlantic (BOTA) Research Project from

June 8-30, 2010. Off the coast of Cape Hatteras, in 23 - 72 meters of water, researchers 

conducted the first biological surveys of several historic shipwrecks. The data collected 

included fish, invertebrate and algal surveys, and the deployment of temperature sensors.

Researchers from the National Centers for Coastal Ocean Science (NCCOS) and National 

Marine Fisheries Service (NMFS) partnered with the MNMS to design sampling 

protocols for this mission. The information collected will not only establish a baseline, 

but will be used to support management documents such as future MNMS Condition 

Reports. Without this baseline data, determining changes and trends necessary for the 

Condition Report is impossible. In order to gain a better understanding of the biological 

community in and adjacent to the sanctuary and to begin to resolve unanswered questions 

from the 2008 MNMS Condition Report, the following goals were addressed:
4

• Establish and maintain a monitoring and research program of the MNMS’s living 

resources and their habitats. 

• Establish and promote specific sites within and adjacent to the sanctuary as

locations for long-term monitoring.

The main objectives of this report are 1) to summarize the activities conducted and the 

biological communities present on the shipwrecks surveyed during the 2010 BOTA 

cruise, 2) present results of the surveys within the context of the oceanographic and 

climatic regime that prevailed during the mission, and 3) provide recommendations on 

the use of shipwrecks as potential sites for detecting community change.

Methods 

Baseline community surveys were conducted at three historic shipwreck sites within two 

of the oceanographic zones south of Cape Hatteras: the middle shelf (20-40m (Keshena

and Dixie Arrow) and outer shelf greater than 60m (EM Clark). North of Cape Hatteras, 

one site was surveyed on the middle shelf (City of Atlanta) (Figure 1, Table 1). At each 

site HOBO Pro v2® water temperature data loggers were deployed that were 

programmed to collect water temperature data once every 30 minutes. These temperature 

sensors will continue to log continuous measurements for up to 2 years. A temperature 

sensor was deployed at one additional site on the middle shelf south of Cape Hatteras 

(Manuela); however, no biological assessments were completed at this site due to 

inclement water conditions and time constraints. 
5

Figure 1. Map of shipwreck locations visited during BOTA 2010 expedition. (Map created by Paula 

Whitfield)

Table 1. Shipwrecks where biological surveys were conducted and/or where temperature sensors 

were placed during the 2010 Battle of the Atlantic expedition. This table does not include the Empire 

Gem or Monitor where only archaeological surveys were conducted. Vis. is abbreviated for visibility.

n* = number of transect conducted at a site. 

Sites

Dates 

surveyed 

(2010)

Depth 

(m)

Temp.

Sensor 

(y/n)

Biological 

surveys 

(n*)

Bottom 

Water 

Temp. (F)

Year

Sunk

Vis. 

(m)

City of 

Atlanta June 11 23 y Fish (1), 

Habitat (1) 53° 1942 10

Dixie 

Arrow

June 12, 

June 25 25 y

Fish (2), 

Habitat (1)

70° 

75° 1942 10

EM 

Clark June 15 72 y Fish (1), 

Habitat (1) 70° 1942 8

Manuela June 16 44 y n/a unk 1942 12

Keshena June 22 25 y Fish (2), 

Habitat (1) 72° 1942 8
6

Fish Community Assessments

All sampling protocols have inherent biases that can favor or exclude species based on 

factors such as behavior, habitat preference, or size (Allen et al. 1992, MacNeil et al. 2008). 

For example, traditional underwater visual census (UVC) transects geared towards 

conspicuous and highly mobile species may miss or underestimate smaller, benthic dwelling 

fishes. These smaller species are often cryptically colored and can either be the juvenile stage 

of conspicuous species or may remain cryptic and small throughout their life cycles, where

they may function as important prey species within the fish community. For this reason, three 

different sampling approaches were combined in order to better capture the entire fish 

community within a given area. The first, a traditional UVC band transect method was used 

to enumerate all conspicuous fish species within 5m on either side of the transect 

(Sanderson and Solonsky 1986, Samoilys and Carlos 2000, Schmitt et al. 2002). The fish 

observer swam along the transect of each shipwreck, observing all mobile, conspicuous 

fishes within the transect band (10m total width, hereafter called “conspicuous fish 

transect”) were enumerated and lengths estimated (using 10cm size classes). The transect 

length was 50m but sometimes varied (30-50 m) due to dive time limitations. Once the 

diver swam 50m, or the temporal midpoint of the bottom time of the dive was reached 

(whichever came first), the diver began reeling in the meter tape and enumerating and 

estimating sizes (up to 10cm length) of the smaller, cryptic, prey fishes (hereafter called 

“prey fish transect”). The second sampling method targeting cryptic (or juvenile) prey 

fishes occurred when the survey was conducted in reverse along the same transect but 

with a narrower width (1m to each side). Due to time constraints, only one transect 

(conspicuous and prey) per shipwreck was conducted unless the site was revisited (e.g., 

Dixie Arrow and Keshena). Finally, one cryptic fish census was also conducted (limited 

by personnel availability) using a timed stationary quadrat method (at the Keshena). The 

purpose of the stationary quadrat technique was to sample smaller cryptic fishes that 

could be missed or underestimated on band transects (data in Appendix A).

Summary of fish community survey methods:

1. 50m x 10m (unless time limited) UVC band transects that targeted mobile 

conspicuous fishes (maximum area surveyed = 500m2

, variable depending on 

visibility and transect length).

2. 50m x 2m UVC band transects that targeted cryptic (or juvenile) prey fishes 10cm 

and less in length (maximum area surveyed = 100m2

).

3. Stationary UVC of 1m2 quadrat (conducted only at the Keshena) placed on the 

benthos for a predetermined (7 min.) time period. This method favors the less 

mobile cryptic prey species less than 20cm but does not exclude conspicuous species 

(area surveyed = 1m2). 

For each site, the number of individuals and densities of fish were calculated. Densities 

were determined by dividing the number of fish observed by the area surveyed (reported 

in hectares). Species richness was also calculated using Pielou’s evenness and the 

Shannon diversity index to further compare the conspicuous fish communities at each 

site. The Shannon diversity index takes into account the number of species and the 
7

evenness of the species, the greater the index value the more diverse and even the species 

composition. Pielou’s species evenness is an index from 0 to 1 where 1 represents an 

equal apportionment of individuals among species (Clark and Warwick 2001). 

Similarity among the fish communities were examined by site using multi-dimensional 

scaling (MDS) analysis of fish densities with PRIMER v6 software. PRIMER allows 

multivariate analysis of community ecology variables without the need to satisfy many of 

the assumptions needed for parametric statistics (Clark and Warwick 2001). In the MDS 

plots, distance is a proxy for both similarity and dissimilarity (Clark and Gorley 2006), 

thus points that are farther from each other are the most dissimilar in their fish 

communities. A square root transformation was used to minimize the influence of 

extremely rare species relative to common ones. 

MDS analyses on fish biomass was also determined for each fish species and site. 

Biomass was calculated from the length-weight relationship, W = aLb

, where w = weight 

in g and L = length in cm. The midpoint of the size categories was calculated for each 

10cm category. For example, if the size category was 20-30cm, then the length was 

considered 25cm for the equation (Kendall et al. 2009). Values for the a and b parameters 

for each species were obtained from http://www.Fishbase.org (Froese and Pauly 2010). If 

the parameters for a particular species could not be found, then the parameters for a 

morphologically similar species within the same genus were used. Parameters for 

whitespotted soapfish (Rypticus maculatus) were not available in the literature or in the

fishbase database, therefore, it was omitted from the biomass analysis. 

Benthic Habitat Assessments

Benthic habitat surveys were conducted concurrently with fish assessments. Using the 

fish transect as a guide, the benthic habitat surveyor took photographs (standardized with 

0.25m2 area) every five meters, beginning at the zero meter. Due to varied transect 

length, the number of images per transect ranged from six to nine (see Table 3 for sample 

sizes). All photographs were taken at 7.0 mega pixel resolution by an experienced 

photographer. Percent cover of uncolonized substrate and epibiota was determined using 

Coral Point Count (CPCe) software (Kohler and Gill 2006). Fifty random points 

(asymptote of species accumulation curve conducted on images from North Carolina 

hardbottom reefs, data not shown) were overlaid on each photograph and the substrate 

type below each random point was classified to the finest taxonomic level possible 

(Figure 2). Only the top-most substrate type was classified and as a result, the amount of 

actual wreck underneath is under-represented at each site. 

In instances where species or genus could not be identified, a classification based on 

morphology was made. For example, where species was unknown but phyla were 

identifiable, a point could be classified as 'rod shaped soft coral' or 'strap-like red algae.' 

Detailed description of species and morphological classes within each benthic habitat 

group is listed in Appendix B. Where phyla were unidentifiable (generally due to 

shadowing, image quality, or obstruction) the point was labeled as unknown and not 
8

included in analysis. For example, 50 points were overlaid on each image but the actual 

number of classifiable, and therefore analyzable, points is identified in Table 3. Percent 

cover was then calculated based on the number of classifiable points. 

The null hypothesis of “no difference in benthic habitat by site” was tested using multidimensional scaling (MDS) analysis and the analysis of similarity (ANOSIM) test in 

PRIMER v6 software. The role of individual benthic components responsible for 

statistical differences was further examined with the similarity percentages (SIMPER) 

routine. 

Figure 2. Examples of analyzed benthic habitat quadrats from each of the sites surveyed. Yellow box 

(25 x 25cm) delineates the analysis area of each image where 50 points are overlaid and classified to 

the finest taxonomic level possible. 
9

Results

The shipwreck sites were located along a cross section of the shelf at water depths of 23 -

72m. Water temperatures during the sampling period in June ranged from 53 -78 ̊F. 

Overall, water conditions at depth were anomalous, especially for June, being much 

colder than expected throughout the time period of sampling (first author observation). 

Reports from fishermen in the area affirmed that the persistence of a cold water layer 

closer to shoreline (than usual) seemed to be influencing fish distributions in these areas. 

Many fishermen stated that they had to ‘run’ 40 miles or more offshore to locate the Gulf 

Stream, which was usually about 20 miles east from Hatteras or Ocracoke Inlet (Capt. 

Terry Leonard, pers. comm.) These observations are important because the surveyed 

abundance and diversity of fish species was lower than expected and the cold water layer 

was a likely cause (Sedberry and Van Dolah 1984). In some cases, poor water clarity also 

seriously hampered visibility needed to conduct surveys.

Fish Community Assessments 

For all sites combined, 32 species of conspicuous fish and nine species of prey fish were 

observed (Appendix A). Eight conspicuous fish species made up 95% of the total number 

of fishes, including red barbier (Hemanthias vivanus), scad (Decapturus spp.), tomtate 

(Haemulon aurolineatum), longspine porgy (Stenotomus caprinus), vermilion snapper 

(Rhomboplites aurorubens), pinfish (Lagodon rhomboids), gray triggerfish (Balistes 

capriscus), and southern sennet (Sphyraena picudilla)(Figure 3A). For the fishes 

observed on the prey transects (fish up to 10cm in length), red barbier and longspine 

porgy represented over 95% of the total number of prey observed (Figure 3B). Ninety 

percent of the conspicuous fish biomass was comprised of 12 species including 

amberjack (Seriola dumerili), vermilion snapper, Mycteroperca spp., and gag grouper 

(Mycteroperca microlepis) (Figure 4A). Ninety-eight percent of the prey fish biomass 

was comprised of two species: red barbier and longspine porgy (Figure 4B).

For each site, the total number and densities of fishes were calculated. The sites that 

contained the highest number of conspicuous fishes were the Keshena (Figure 5A, 16 

species censused over two days) and the Dixie Arrow (Figure 6C, 14 species censused 

over two days). The EM Clark had seven species (Figure 6A) and the City of Atlanta had 

the least, with only two species (Figure 5B). All of the sites that were surveyed had fewer 

species on the prey transects. The Dixie Arrow had the most, with seven prey species 

(Figure 6D). The EM Clark had three species (Figure 6B) and the City of Atlanta had 

only one species, black sea bass (Centropristis striata) (density = 822/hectare). There 

were no prey transects conducted at the Keshena due to time constraints. The highest 

density conspicuous fish species were red barbier at the EM Clark (67,000 /hectare) and 

scad (50,000/hectare), tomtate (14,666/hectare), longspine porgy (5371/hectare) and 

vermilion snapper (2583/hectare) at the Dixie Arrow.
10

Figure 3. Total number of A) conspicuous fishes and B) prey fishes for all sites.
11

Figure 4. Biomass for A) conspicuous fishes for all sites and B) prey fishes for all sites.
12

Figure 5. Densities of conspicuous fishes for the A) Keshena and B) the City of Atlanta.
13

Figure 6. Densities of conspicuous and prey fishes for the A) B) EM Clark and the C) D) Dixie Arrow.

The results of the MDS analysis suggest that the conspicuous fish community among 

sites was different (Figure 7). Although insufficient replicates preclude a statistical 

analysis such as ANOSIM, the 10% similarity contours suggest that the fish communities 

at the Dixie Arrow and the Keshena were most similar to each other. This is not 

surprising because these two sites are geographically close to each other and are located 

at analogous depths and therefore, presumably share a similar oceanographic regime. The 

northernmost and most isolated of the sites, the City of Atlanta, was the most dissimilar in 

both species composition and density compared to the other sites. The EM Clark was the 

deepest site surveyed and was also shown to be dissimilar to the other sites. Results from 

the MDS analysis of the prey community yielded very similar results and are not 

presented here to avoid redundancy.
14

Figure 7. Multi-dimensional plot of the conspicuous fish community at all sites with 10% similarity 

contour overlaid.

The Dixie Arrow and the Keshena had the highest species richness and the highest 

Shannon diversity index (Table 2). The City of Atlanta had the lower diversity and a 

relatively high evenness index because there were only two species observed in relatively 

equal numbers, whereas the EM Clark has a low evenness index because the red barbier 

vastly outnumbered the other species at the site (Table 2, Figure 6A). These results also 

suggest that the middle shelf sites south of Cape Hatteras were more diverse than the 

outer shelf site, the EM Clark. Results of prey community diversity analyses were again 

similar and not presented here to avoid redundancy.

Size classes for the conspicuous (32 species, Figures 8 to 12) and prey fishes (nine 

species, Figures 13-14) are presented in order of descending biomass. For example, in 

Figure 4 whitespotted soapfish (Rypticus maculatus) was included last because there 

were no biomass parameter estimates available for this species. 
15

Table 2. Diversity indices for conspicuous species by site. 

Site Date

Area 

surveyed

(m2)

Species

richness

Evenness 

index 

(Peilou’s)

Shannon 

diversity 

index

Oceanographic

zone

City of 

Atlanta 06/11/2011 300 2 0.9911 0.687

middle

shelf north 

of C. 

Hatteras

EM 

Clark 06/15/2011 150 7 .06922 0.144 outer shelf

Dixie 

Arrow 06/12/2011 200 10 0.4637 1.068 middle

shelf

Dixie 

Arrow 06/25/2011 330 13 0.6422 1.647 middle

shelf

Keshena 06/22/2011 400 13 0.7078 1.816 middle

shelf

Keshena 06/23/2011 400 11 0.7087 1.699 middle

shelf
16

Greater Amberjack

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

A Scad

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

200

400

600

800

1000

1200

Gray Triggerfish

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

10

20

30

40

50

60

Tomtate

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total number by Size Class

0

100

200

300

400

500

600

Vermilion Snapper

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80

L80-90

90to100

Total Number by Size Class

0

20

40

60

80

100

Mycteroperca species - Grouper

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

B

C D

E F

Figure 8. Size class graphs of conspicuous fishes representing the top six species in biomass.
17

Almaco Jack

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

A Tautog

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Longspine Porgy

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

20

40

60

80

100

120

140

160

180

Pinfish

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

20

40

60

80

100

120

Atlantic Spadefish

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80

L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

12

14

Gag

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80

L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

B

C D

E F

Figure 9. Size class graphs of conspicuous fishes representing the top seven to 12 species in biomass.
18

Sheepshead

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

A Black Sea Bass

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Red Barbier

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

200

400

600

800

1000

1200

Oyster Toad

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Spottail Pinfish

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

5

10

15

20

25

30

Calamus species

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

B

C D

E F

Figure 10. Size class graphs of conspicuous fishes representing the top 13 to 18 species in biomass.
19

Queen Angel

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

A Southern Sennet

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

5

10

15

20

25

30

Yellowmouth Grouper

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Cubbyu

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Belted Sandfish

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80

L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Bank Sea Bass

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

B

C D

E F

Figure 11. Size class graphs of conspicuous fish species representing the top 19 to 24 species in 

biomass
20

Slippery Dick

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

A Sand Tiger

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

5

10

15

20

Brown Chromis

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Crested Blenny

L1-10

L10-20L20-30

L30-40L40-50

L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Seaweed Blenny

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

Painted Wrasse & Whitespotted Soapfish*

L1-10

L10-20L20-30L30-40L40-50L50-60L60-70L70-80L80-90

90to100

Total Number by Size Class

0

2

4

6

8

10

painted wrasse 

whitespotted soapfish

B

C D

E F

Figure 12. Size class graphs of conspicuous fishes representing the last 25 to 32 species in biomass.

* Parameters to estimate biomass of whitespotted soapfish were not available.
21

Red Barbier

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

100

200

300

400

500

A Longspine Porgy

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

50

100

150

200

Belted Sandfish

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

Black Sea Bass

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

Tomtate

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

1

2

3

4

5

6

Slippery Dick

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

B

C D

E F

Figure 13. Size classes for prey fishes representing the top six species in prey fish biomass.
22

Seaweed Blenny

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

A Bank Sea Bass

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

Cubbyu

LT2

L2-5L5-7

L7-10

Total Number by Size Class

0

2

4

6

8

10

B

C

Figure 14. Size classes for prey fishes representing the last seven to nine species in prey fish biomass.
23

Benthic Habitat Assessments

The biotic and abiotic components of the surveyed wrecks were comprised of 33 different 

species and morphological groups, spanning 10 phyla (Appendix B, Figure 15). Images 

collected in June 2010 for benthic habitat analysis were of exceptional quality (Figure 2), 

with a mean of 91.25% (± 1.83 SE) of all points being identifiable at each site. The 

majority of unidentifiable points were due to shadowing (5.1% ± 1.49, mean ± SE), 

which is not unexpected given the complexity and rugose nature of the surveyed wrecks. 

Figure 15. Photo of the diverse invertebrate community on the EM Clark (72m) with schooling red 

barbier (Hemanthias vivanus). Photo credit: Doug Kesling (CIOERT)

Results of MDS analysis and the ANOSIM test revealed significant differences in the 

benthic community among the four wrecks examined (Figure 16, Global R 0.45, p < 

0.0001). The SIMPER routine provided a list of the community components that were 

responsible for the differences among the sites (Table 3.). For example, at the EM Clark
24

the contributions of barnacles to the percent dissimilarity ranked high because barnacles 

were not found in high amounts on any other shipwreck (Figure 17). Likewise, the 

contribution of Telesto (octocoral) and anemones (cnidarian) to the percent dissimilarity 

of City of Atlanta versus other shipwrecks were relatively high due to the percent cover 

of these community components being greater than on any other shipwreck (Figure 17). 

Although the Keshena and Dixie Arrow share a similar oceanographic regime, the 

average dissimilarity among these two shipwrecks was 69%. Nearly 18% of this 

dissimilarity was due to the high amount of sand, shell and shell hash found at the 

Keshena (Table 3, Figure 17). 

Figure 16. Multi-dimensional plot of benthic habitat percent cover data for each site with the 40% 

similarity contour overlaid to illustrate site differences.
25

Table 3. Average dissimilarities between sites and percent contributions to the average dissimilarities 

of individual benthic habitat components are reported. Results of SIMPER, listed are species 

composing top 70% dissimilarity.

Component Percent Component Percent

Keshena vs. City of Atlanta

Avg. DISSIMILARITY=66.75

Crustose coralline

Anemone 

Sediment – sand

Telesto sp.

Shell/shellhash

Oculina sp.

Film

13.45

13.21

12.54

11.13

9.92

6.98

6.56

City of Atlanta vs. EM Clark

Avg. DISSIMILARITY=79.49

Telesto sp.

Barnacle 

Anemone

Wreck

Crustose coralline

Film

19.82

13.13

12.21

10.68

8.97

7.26

Keshena vs. Dixie Arrow

Avg. DISSIMILARITY=69.04

Telesto sp.

Sediment - sand

Shell/shellhash

Filamentous Red Algae

Sargassum filipendula

Film

Crustose coralline 

Bryozoans

Euhermania gigantea

Hydroid

Wreck

9.64

9.34

8.33

7.29

6.83

6.70

6.32

5.70

4.83

3.94

3.17

Dixie Arrow vs. EM Clark

Avg. DISSIMILARITY=68.99

Barnacle 

Wreck

Film

Crustose coralline

Filamentous red algae

Sargassum filipendula

Arbacia punctulata

Bryozoans 

Euhermania gigantea

11.65

10.58

10.45

8.30

7.75

7.27

5.76

5.22

5.12

City of Atlanta vs. Dixie Arrow

Avg. DISSIMILARITY=82.48

Telesto sp.

Crustose coralline

Anemone .

Filamentous red algae

Sargassum filipendula

Film

Bryozoans

Oculina sp.

Euhermania gigantea

16.30

14.68

9.35

6.83

6.41

5.56

5.55

5.17

4.50

Keshena vs. EM Clark

Avg. DISSIMILARITY=62.59

Barnacle 

Sediment – sand

Telesto sp.

Shell/shellhash

Wreck

Crustose coralline

Film

13.98

12.69

12.43

10.03

8.81

7.19

7.05
26

Macroalgae Community 

Macroalgae was the second most abundant biotic community, with an average cover of 

23% per site. Predominant genera for all sites combined were crustose 

coralline/Peyssonnelia sp. (14% ± 6.3), Sargassum sp. (3% ± 3.2), filamentous red (2% ±

2.4), and fuzzy green algae (1.5% ± 1.5). Sargassum sp., a filamentous red, and a fuzzy 

green algae were found exclusively at the Dixie Arrow, which explained the higher 

standard error. Red algae (rhodophyta) was the most abundant (17% ± 8.9 per site) of the 

three macroalgal divisions (rhodophyta, phaeophyta, chlorophyta), and was largely found 

at the Dixie Arrow (Figure 17A). Macroalgae were not found at the City of Atlanta, 

differing greatly from the Dixie Arrow, where macroalgae comprised the dominant cover 

type (62%, Table 4). Greatest algal diversity was found at Dixie Arrow (nine species + 

morphological groups). 

Invertebrate Community

Cnidarians were the most abundant biotic community type for all sites combined (26% ±

15.1). Type and cover of cnidarians differed among sites (Figure 17), with greatest cover 

at the City of Atlanta (Table 4). Predominant taxa/components at the City of Atlanta

included Telesto sp. (44%), anemones (19%), and Oculina sp. (5%), and these species 

were among the most abundant species for all sites combined (15% ± 10.3, 5% ± 4.6, 

1.5% ± 1.3 respectively) in addition to hydroids (1.7% ± 0.7). Coral cover consisted 

exclusively of Oculina sp. and was found at the City of Atlanta and the Dixie Arrow. 

Although absent from analyzed photos, cup coral (possibly Phyllangia americana or

Paracyathus pulchellus) was also found in low densities in other descriptive photographs. 

At the EM Clark, the large cover (19%) of crustaceans recorded consisted solely of 

barnacles. They were also found at the Dixie Arrow and the Keshena but in much lower 

cover (0.9%, 0.5% respectively). Additional noteworthy invertebrates found were the 

ascidian (tunicate), Euhermania gigantea (8% at Dixie Arrow) and echinoderm, Arbacia 

punctulata (purple-spined sea urchin) at the Dixie Arrow (3.4%) and the EM Clark

(7.7%). No other echinoderms were recorded. A. punctulata is commonly found on live 

rock reefs off North Carolina. Barnacles and E. gigantean are less common on North 

Carolina temperate hardbottom reefs (Whitfield et al. unpub. data). Occasionally, a fish 

was photographed within the quadrat area. When a random point landed on a fish it was 

scored as a 'vertebrate' but species was not identified. Vertebrates (all fish) were recorded 

as a small percentage at the Keshena (1.2%) and the EM Clark (0.3%).

Abiotic Composition

The abiotic components or exposed substrate, was the most common cover type overall 

(35% ± 11.3 of total cover). Predominant abiotic cover types included exposed wreck 

(4% ± 3.3), inorganic-organic film (23% ± 6.1), sediment (4% ± 3.9), and shell / shell 

hash (3% ± 3.3). Inorganic-organic film is defined as a composite of benthic microalgae 

and inorganic silts, but microscopic observation would be required for absolute 
27

confirmation. Sediment was documented only at Dixie Arrow (1.4%) and Keshena 

(16%), shell/shell hash was found exclusively at Keshena (13%). The higher cover of 

sand and shell are not unexpected, as Keshena was more fragmented, in smaller parts, 

and had more sand encroachment than the other sites surveyed.

Table 4. Mean percent cover of major benthic habitat groupings from all sites surveyed.

* Listed are classifiable points, all unclassified points were removed prior to cover calculations. Taxa

within each group are listed in Appendix B.

City of Atlanta Dixie Arrow EM 

Clark

Keshena Mean

Algae 0.00 62.07 10.45 18.52 22.76

Cnidarian 70.04 5.46 7.32 20.74 25.89

Porifera 7.22 0.57 0.00 2.22 2.50

Ascidian 0.00 10.06 0.00 0.25 2.58

Echinodermata 0.00 3.45 7.67 0.00 2.78

Crustacean 0.00 0.86 19.16 0.49 5.13

Mollusca 0.00 0.00 0.00 0.74 0.19

Other 

Invertebrates 1.44 6.61 1.39 0.25 2.42

Vertebrates 0.00 0.00 0.35 1.23 0.40

Exposed Substrate 21.30 10.92 53.66 55.31 35.30

Marine Debris 0.00 0.00 0.00 0.25 0.06

N frames (points*) 6

(277)

8

(348)

6

(287)

9

(405)

7.25

(329.25)
28

0

10

20

30

40

50

60

Percent Cover

CPR

0

10

20

30

40

50

Percent Cover

COC

0

10

20

30

40

50

60

70

Percent Cover

SUBSTRATE

0

5

10

15

20

Percent Cover

CEMAVO DP

Sites

City of Atlanta

Dixie Arrow

EM Clark

Keshena

A. Algae B. Cnidarians

C. Exposed Substrate

D.

Figure 17. Percent cover by major benthic habitat category at all sites.
29

Discussion/Future Recommendations

Strong differences in both the fish and benthic habitat components were observed among 

most of the shipwrecks surveyed. These differences generally appeared to correlate with 

the oceanographic zone (depth), especially for the fish community surveys (Figure 7). 

These findings concur with the results of five years of fish surveys on temperate 

hardbottom reefs in North Carolina that found statistical differences among the fish 

communities based on the inner shelf (0-20m), middle shelf (20-40m) and outer shelf 

(40-60m) designations (Whitfield et al. unpub. data). Previous studies that extended into 

deeper water also found distinct faunal assemblages on the shelf (27-64m) and shelf edge 

(64-183m) (Grimes et al. 1982). In a trawl study, Sedberry and Van Dolah (1984) found 

fish abundance highest in the middle shelf locations (25-38m).

In general, the middle shelf region has been described as a thermally stable, transitional 

zone containing the highest diversity of organisms across the continental shelf (Wenner et 

al. 1983, Sedberry and Van Dolah 1984, Schobernd and Sedberry 2009). In this study, 

fish community diversity was the highest at the middle shelf locations (Keshena and 

Dixie Arrow) and the least diverse at the City of Atlanta (also middle shelf, but north of 

the zoogeographic break at Cape Hatteras). The low diversity at the City of Atlanta is 

likely attributed to the colder water temperatures that exist for much of the year compared 

to the other sites surveyed during this mission. Due to its proximity north of Cape 

Hatteras, it is influenced not by the Gulf Stream but by temperate and cold water currents 

such as the Virginia current and the Labrador current. At the time of the surveys, water 

temperatures on the City of Atlanta were 53° F. Although the EM Clark (72m) is located 

closest to the Gulf Stream, the fish community showed less diversity than expected (eight 

species), with few tropical species. This may have been due to the influence of cold water 

upwelling that most often occurs in deepwater shelf locations and results in greater 

thermal instability compared to middle shelf locations (Atkinson et al. 1983, Yoder 1991, 

Aretxabaleta et al. 2007). Cold water upwelling occurs intermittently along the North 

Carolina coast during the warm summer months (April-November) and can be 

responsible for fish kills or movement of fishes from an affected area (Huntsman 1976, 

Atkinson et al. 1983). However, Gulf Stream upwelling is also one of the main vectors 

for the influx of nutrients upon the shelf (Atkinson et al. 1983). It is possible that the 

anomalous cold water conditions that were experienced during this study may have been 

a result of Gulf Stream upwelling and the reason for the low diversity at the EM Clark. In 

this study, a total of 34 fish species from 18 different families was censused (Appendix 

A). In comparison, in a five year study on natural hardbottom reefs off North Carolina, a 

total of 157 species from 45 families was observed (Whitfield et al. unpubl. data). 

However, it is important to note that the present study was limited in time and geographic 

extent, and was conducted during adverse temperature conditions. 

The results of the benthic habitat photo-quadrat analysis indicated statistically significant 

differences among all sites surveyed, even those closest to each other, the Keshena and 

Dixie Arrow. Although these two shipwrecks share a similar oceanographic regime, the 
30

Dixie Arrow was characterized by a higher percent cover of algae (filamentous red and 

Sargassum filipendula), while the Keshena had a higher percent cover of sand, shell/shell 

hash and octocorals (Telesto sp.). However, this variation is not likely attributable to

differences in oceanographic regime due to their close proximity to each other on the 

middle shelf (~6 miles)(Figure 1.). Instead, it is more likely that these striking 

differences in the benthic habitat community are due in part to localized variables such as 

the shipwreck relief, size and/or orientation as the Dixie Arrow is much larger, more 

intact, with less sand encroachment than the Keshena. The results from the City of 

Atlanta revealed higher percent cover of anemones and octocorals than the other sites. It 

is likely the temperate waters found north of Cape Hatteras which tend to be colder, 

darker and nutrient rich are driving the water column food chain with an abundance of 

plankton and zooplankton which in turn can limit light at depth. As filter feeders, 

anemones and octocorals would be able to feed on these resources and outcompete other 

organisms, such as algae that need more light, for space on the shipwreck. In the case of 

the EM Clark, it was characterized with the highest percent cover of barnacles. However, 

at this point, it is unclear why barnacles composed such a high percent cover on this 

shipwreck. It may simply be due to the sampling location, the starboard hull of the wreck, 

where there is very little micro-habitat complexity. This side was largely devoid of sessile 

invertebrates, with the exception of barnacles, while large areas of zooanthids, anemones 

and soft corals were observed intermittently on the superstructure (Figure 15). Perhaps 

the top of the shipwreck experiences more current shear and barnacles favor these areas. 

In general, community composition also varies with age (Forteath et al. 1982); the 

shipwrecks surveyed in this study were all sunk in 1942 and had metal hulls. Spatial 

heterogeneity of the epibenthic community is well documented, where shipwreck 

orientation, surface composition, and hydrodynamic regime are considered the major 

factors capable of influencing community structure (Baynes and Szmant 1989, Lindquist 

and Pietrafesa 1989, Glasby 2000, Glasby and Connell 2001, Knott et al. 2004, Walker et 

al. 2007). Heterogeneity of the benthic habitat within the individual shipwrecks 

themselves was also observed, not only on the EM Clark but also on the Keshena where 

sand is encroaching the bottom of the shipwreck. To reduce the inherent variability in the 

benthic habitat within a site, it is imperative to use a sampling design that takes into 

account the within-site heterogeneity. For example, for a shipwreck like the EM Clark,

consistently sampling different parts of the wreck to capture the natural variability at the 

site would reduce the potential for year-to-year variability caused by inconsistent 

sampling on one location only. Likewise, consistency in sampling methodology is 

important for surveying the fish community as well. To capture the fish community, 

sampling several times throughout the year or at least during the same season each year

could aid in getting a better understanding of the fish community at a site. However, 

many fish will move in response to variable water conditions (i.e. current, temperature 

etc.) therefore, it is best to sample more than one time a year to fully characterize a 

location. 

Based on these considerations, to utilize these shipwrecks as sites for detecting 

community shifts due to climate change or other stressors (e.g., overfishing), it is 

imperative to expand the scope of sampling both temporally and numerically. It is 
31

recommended that a subset of sites both within an oceanographic zone and across the 

shelf be repeatedly sampled over time. We also recommend increasing the sample size 

within each site to reduce the sampling variability within and among sites for the benthic 

and fish communities. These alterations will accommodate the natural differences in 

oceanographic regime that are known to exist across the shelf. Similarly, increased 

sample size on each wreck will reduce the within-site heterogeneity observed in the 

benthic community and provide the replication necessary for statistical analyses. Finally, 

incorporating bottom water temperature data (as sensors are retrieved) and other variables 

such as salinity, shipwreck area, and relief into future analyses will aid in relating fish 

and benthic community structure with local environmental variables. 

In addition to their cultural significance, shipwrecks function as important habitat for a 

wide variety of fishes, invertebrates and algal species. In addition, due to their unique 

location off North Carolina at a natural zoogeographic transition zone, shipwrecks can 

also be important to understanding how our oceans and the communities within them are 

changing. The research presented in this study represents the first step in understanding 

how to implement a statistically valid sampling program that can utilize submerged 

cultural resources as sites for understanding community change. 
32

Appendix 

Appendix A. Comprehensive fish species list.

Families and species of all fishes found during the MNMS Battle of the Atlantic (BOTA) 

sampling from June 8-30, 2010. * indicates the type of survey in which the species was 

observed; c-conspicuous transect, p-prey transect, q-stationary quadrat, o-off- transect 

only. Whether the fish was observed (Y) or not (N) on NC temperate reefs during 2005-

2010 sampling period in water depths from 75-150fsw, is also listed.

Family Common Names Genus species Sampling 

type*

Balistidae

gray triggerfish Balistes capriscus c, y

Batrachoididae

oyster toad Opsanus tau c, q, y

Blenniidae

crested blenny Hypleurochilus geminatus c, n

seaweed blenny Parablennius marmoreus c, p, q, y

Carangidae

almaco jack Hypleurochilus geminatus c, y

greater 

amberjack Seriola dumerili

c, y

scad Decapterus species c, y

Coryphaenidae

dophinfish Coryphaena hippurus o, n

Ephippidae

atlantic spadefish Chaetodipterus faber c, q, y

Gymnuridae

smooth butterfly 

ray

Gymnura micrura o, n

Haemulidae

tomtate Haemulon aurolineatum c, p, y

Labridae

painted wrasse Halichoeres caudalis c, y

slippery dick Halichoeres bivittatus c, p, y

tautog Tautoga onitis c, y
33

Lutjanidae

vermilion 

snapper Rhomboplites aurorubens

c, y

Odontaspididae

sand tiger Odontaspis taurus c, n

Pomacanthidae

queen angelfish Holacanthus ciliaris c, y

Pomacentridae

brown chromis Chromis multilineatus c, y

Sciaenidae

cubbyu Pareques umbrosus c, p, y

Serranidae

bank sea bass Centropristis ocyurus c, p, y

black sea bass Centropristis striata c, p, q, y

belted sandfish Serranus subligarius c, p, y

gag Mycteroperca microlepis c, y

yellowmouth 

grouper Mycteroperca interstitialis

c, y

mycteroperca 

species Mycteroperca species

c, y

red barbier Hemanthias vivanus c, p, y

whitespotted 

soapfish Rypticus maculatus

c, q, y

Sparidae

longspine porgy Stenotomus caprinus c, p, y

porgy Calamus species c, y

pinfish Lagodon rhomboides c, y

sheepshead Archosargus probatocephalus c, y

spottail pinfish Diplodus holbrookii c, y

Sphyraenidae

southern sennet Sphyraena picudilla c, n

Sphyrnidae

hammerhead 

shark Sphyrna species

o, n
34

Appendix B. Comprehensive benthic habitat group and species list.

Benthic species and groups listed by major category found at four wrecks (City of Atlanta, Dixie Arrow, 

EM Clark and Keshena). * indicates species that were observed on North Carolina temperate reefs during 

2007-2010 sampling period in water depths from 23-50m.

Major category Common names or 

taxonomic group

Species or description of species 

group

Also on NC 

reefs*

Algae Chlorophyta

Codium species Y

Fuzzy Green / Turf Y

Phaeophyta

Dictyota spp. Y

Sargassum filipendula Y

Turf / filamentous Y

Rhodophyta

Crustose coralline / Peysonnelia 

spp.

Y

Rhodymenia pseudopalmata / 

Gracilaria mammalaris Y

Strap-like red Y

Filamentous red Y

Cnidarian Coral / Scleractinia

Oculina sp. Y

Octocoral

Leptogorgia virgulata U

Telesto sp. N

Sea Rod, unknown species Y

Other Cnidarians

Hydroid Y

Anemone Y

Zoanthids Y

Other / Unidentifiable

Poriferans Cliona spp. N

Encrusting sponge, unknown 

species Y

Tunicates / 

Ascidians Euhermania gigantean N

Tunicate, unknown spp. Y

Echinoderms Arbacia punctulata Y

Crustaceans Barnacle U
35

Molluscs Gastropod Y

Other Bryozoans Y

Invertebrates Worms Y

Unknown / Unidentifiable 

Invertebrate Y

Vertebrates Fish (unspecified species) Y

Bottom Types Exposed wreck N

Film (organic / inorganic deposit) Y

Sediment / sand Y

Shell or shellhash Y

Crack / crevice / hole Y

Acknowledgments

We would like to thank the Monitor National Marine Sanctuary for their support of this 

research. We would especially like to thank Dave Alberg and Joe Hoyt. We also express 

our thanks to the crew of the RV-8501: Captain Bob Wallace, Jordan Cousino, Chris 

Fosdick, and Chris Eubanks. In addition, we appreciate the in-water and topside support 

provided by the CIOERT team; Doug Kesling and Scott Fowler. We also thank the divers 

and technical divers: Tane Casserly, Russ Green, Greg McFall, Steve Sellers, John 

McCord, Nathan Richards, John Bright, and Calvin Mires. Of course this research would 

not be possible without Dave Ball, our fearless safety diver throughout the mission.

Finally, we thank Mark Fonseca and Todd Kellison for their support of CCFHR/NMFS

participation in this research mission. We also thank Shay Viehman, Chris Taylor, Patti 

Marraro, Mark Fonseca and Kathy Broughton for their thoughtful reviews of this 

manuscript. 
36

Literature Cited

Allen, L.G., L.S. Bouvier, R.E. Jensen. 1992. Abundance, diversity, and seasonality of

cryptic fishes and their contribution to a temperate reef fish assemblage off Santa 

Catalina Island, California. Bull Southern California Acad Sci 91:55-69.

Aretxabaleta, A., B.O. Blanton, H.E. Seim, F.E. Werner, J.R. Nelson, E.P. Chassignet. 

2007. Cold event in the South Atlantic Bight during summer of 2003: model simulations 

and implications. J Geophys Res 112 C05022, doi:10.1029/2006JC003903.

Atkinson, L.P., T.N. Lee, J.O. Blanton, W.S. Chandler. 1983. Climatology of the 

southeastern United States Continental Shelf Waters. J Geophy Res 88:4705-4718. 

Baynes, T.W., A.M. Szmant. 1989. Effect of current on the sessile benthic community 

structure of an artificial reef. Bull Mar Sci 44:545-566.

Briggs, J.C. 1974. Marine zoogeography. McGraw Hill, New York.

Carr, M.H., M.A. Hixon .1997. Artificial reefs: The Importance of comparisons with 

natural reefs. Special Issue on Artificial Reef Management, Fisheries 22(4):28-33.

Christian, R., Steimle, F., Stone, R., 1998. Evolution of marine artificial reef 

development-A philosophical review of management strategies. Gulf of Mexico Science 

16:32-36.

Clark, K.R., R.N. Gorley. 2006. PRIMER v6: User Manual/Tutorial. PRIMER-E 

Plymouth.

Clark, K.R., R.M. Warwick. 2001. Change in marine communities: an approach to 

statistical analysis and interpretation, 2nd edition. PRIMER-E: Plymouth.

Forteath, G.N.R., G.B. Picken, R. Ralph, J. Williams. 1982. Marine growth studies on the 

North Sea oil platform montrose alpha. Mar Ecol Prog Ser 8:61-88.

Froese, R., D. Pauly. 2010. FishBase, Ver. 11/2010. Accessed 14 April 2011. 

http://www.fishbase.org/

Gentile, G., 1992. Shipwrecks of North Carolina and Hatteras Inlet south. Publisher Gary 

Gentile Productions. 

Gentile, G., 1993. Shipwrecks of North Carolina from the Diamond Shoals North. 

Publisher Gary Gentile Productions. 
37

Glasby, T.M. 2000. Surface composition and orientation interact to affect subtidal 

epibiota. J Exp Mar Biol Ecol 248:177-190.

Glasby, T.M., S.D. Connell. 2001. Orientation and position of substrata have large effects 

on epibiotic assemblages. Mar Ecol Prog Ser 214:127-135.

Grimes, C.B., C.S. Manooch, G.R. Huntsman. 1982. Reef and rock outcropping fishes of 

the outer continental shelf of North Carolina and South Carolina, and ecological notes on 

the red porgy and vermilion snapper. Bull Mar Sci 32:277-289.

Hoyt, J.C. 2010. Battle of the Atlantic Research Expedition 2010, June 8-30, 

Archeaological Survey and Operations Plan. 

Hixon, M.A., J.P. Beets. 1989. Shelter characteristics and Caribbean fish assemblages: 

experiments with artificial reefs. Bull Mar Sci 44(2):666-680.

Huntsman, G.R. 1976 Offshore headboat fishing in North Carolina and South Carolina. 

Marine Fisheries Review 38(3)March MFR Paper 1179.

Kendall, M.S., L.J. Bauer, C.F.G. Jeffrey. 2007. Characterization of the benthos, marine 

debris and bottom fish at Gray’s Reef National Marine Sanctuary. National 

Centers for Coastal Ocean Science (NCCOS) Biogeography Team and the National 

Marine Sanctuary Program. Silver Spring, MD. NOAA Technical Memorandum NOS 

NCCOS 50. 82pp. 

Kendall, M.S., L.J. Bauer, C.F.G. Jeffrey. 2009. Influence of hard bottom morphology on 

fish assemblages of the continental shelf off Georgia, southeastern USA. Bull Mar Sci 

84:265-286.

Knott, N.A., A.J. Underwood, M.G. Chapman, T.M. Glasby. 2004. Epibiota on vertical 

and on horizontal surfaces on natural reefs and on artificial structures. J Mar Biol Assoc 

UK 84:1117-1130.

Kohler, N.E., S.M. Gill. 2006. Coral Point Count with Excel extensions (CPCe): a Visual 

Basic program for the determination of coral and substrate coverage using random point 

count methodology. Comput Geosci 32:1259-1269.

Lindquist, D.G., L.J. Pietrafesa.1989. Current vortices and fish aggregations: The current 

field and associated fishes around a tugboat wreck in Onslow Bay, North Carolina. Bull 

Mar Sci 44:533-544.

Lindquist, D.G., I.E. Clavijo, L.B. Cahoon, S.K. Bolden, S.W. Burk. 1989. Quantitative 

diver visual surveys of innershelf natural and artificial reefs in Onslow Bay, NC: 

Preliminary results for 1988 and 1989, p. 219:227. In: M.A. Lang, W.C. Jaap (eds.) 

Diving for Science 1989. American Academy of Underwater Sciences, Costa Mesa, CA. 
38

MacNeil, M.A., N.A.J. Graham, M.J. Conroy, C.J. Fonnesbeck, N.V.C. Polunin, S.P. 

Rushton, P. Chabanet, T.R. McClanahan. 2008. Detection heterogeneity in underwater 

visual-census data. J Fish Biol 73:1748-1763.

Moura, A., Boaventura D., Cúrdia, J.,Carvalho, S., Cancela da Fonseca, L., Leitāo, F.M., 

Santos, M.N., Monteiro, C.C. 2007. Effect of depth and reef structure on early 

macrobenthic communities of the Algarve artificial reefs (southern Portugal) 

Hydrobiologia 580:173-180. 

Parker, R.O., Dixon, R. L., 1998. Changes in a North Carolina reef rish community after 

15 years of intense fishing – global warming implications. Transactions of the American 

Fisheries Society 127:908:920.

Peckol, P., R.B. Searles. 1984. Temporal and spatial patterns of growth and survival of 

invertebrate and algal populations of a North Carolina continental shelf community. 

Estuar Coast Shelf Sci 18:133-143.

Samoilys, M.A., G. Carlos. 2000. Determining methods of underwater visual census for 

estimating the abundance of coral reef fishes. Environ Biol Fishes 57:289-304.

Sanderson, S.L., A.C. Solonsky. 1986. Comparison of a rapid visual and a strip transect 

technique for censusing reef fish assemblages. Bull Mar Sci 39:119-129.

Schmitt, E.F., T.D. Sluka, K.M. Sullivan-Sealey. 2002. Evaluating the use of roving diver 

and transect surveys to assess the coral reef fish assemblage off southeastern Hispaniola. 

Coral Reefs 21:216-223.

Schobernd, C.M., G.R. Sedberry. 2009. Shelf-edge and upper-slope reef fish assemblages 

in the South Atlantic Bight: habitat characteristics, spatial variation, and reproductive

behavior. Bull Mar Sci 84:67-92.

Seaman, W., 2007. Artificial habitats and the restoration of degraded marine ecosystems 

and fisheries. Hydrobiologia 580:143-153.

Sedberry, G.R., R.F. Van Dolah. 1984. Demersal fish assemblages associated with hard 

bottom habitat in the South Atlantic Bight of the U.S.A. Environ Biol Fishes. 11:241-258.

Renaud, P.E., S.R. Riggs, W.G. Ambrose, K.A. Schmid, S.W. Snyder. 1997. Biologicalgeological interactions: Storm effects on macroalgal communities mediated by sediment 

characteristics and distribution. Cont Shelf Res 17:37-56.

Walker, S.J., T.A. Schlacher, M.A. Schlacher-Hoenlinger. 2007. Spatial heterogeneity of 

epibenthos on artificial reefs: Fouling communities in the early stages of colonization on 

an East Australian shipwreck. Mar Ecol 28:1-11.
39

Wenner, E.L., D.M. Knott, R.F. Van Dolah, V.G. Burrell Jr.. 1983. Invertebrate 

communities associated with the hard bottom habitats in the South Atlantic Bight. Estuar 

Coast Shelf Sci 17:143-158.

Yoder, J.A. 1991. Warm-temperate food chains of the Southeast Shelf Ecosystem, p. 49-

66. In: R. Sherman, L.M. Alexander LM, B.D. Gold (eds.) Food Chains, Yields, Models 

and Management of Large Marine Ecosystems. Westview Press, Boulder, CO.