Impact of the Charleston Ocean Dredged Material Disposal Site on nearby hard bottom reef habitats

Marine Pollution Bulletin 60 (2010) 679–691

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Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul

Impact of the Charleston Ocean Dredged Material Disposal Site on nearby hard bottom reef habitats Stacie E. Crowe a,*, Paul T. Gayes b, Richard F. Viso b, Derk C. Bergquist a, Pamela C. Jutte a, Robert F. Van Dolah a a b

Marine Resources Research Institute, South Carolina Department of Natural Resources, 217 Fort Johnson Road, Charleston, SC 29412, USA Center for Marine and Wetland Studies, Coastal Carolina University, Conway, SC 29526, USA

a r t i c l e

i n f o

Keywords: Dredged material disposal Hard bottom reef habitat Finfish Sponge Coral Sediment Charleston South Carolina

a b s t r a c t The deepening of shipping and entrance channels in Charleston Harbor (South Carolina, USA) was completed in April 2002 and placed an estimated 22 million cubic yards (mcy) of material in the offshore Charleston Ocean Dredged Material Disposal Site (ODMDS). To determine if sediments dispersed from the ODMDS were negatively affecting invertebrate and/or finfish communities at hard bottom reef areas around the disposal area, six study sites were established: three close to and downdrift of the ODMDS and three upcurrent and farther from the ODMDS. These sites were monitored biannually from 2000 to 2005 using diver surveys and annually using simultaneous underwater video tows and detailed sidescansonar. In general, the sediment characteristics of downdrift sites and reference sites changed similarly over time. Overall, the hard bottom reef areas and their associated communities showed little evidence of degradation resulting from the movement of sediments from the Charleston ODMDS during the study period. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction Coastal sediments dredged from waterways, ports and harbors to maintain navigational channels for commercial, national defense and recreational purposes represent the largest mass of discharged waste in the ocean, resulting in the relocation of more than 3  108 m3 of material annually in the United States alone (Kester et al., 1983; Kennedy, 2006). In the United States, ocean disposal of dredged material is only permitted at ocean dredged material disposal sites which are designated by the United States Environmental Protection Agency (USEPA) and used until they reach maximum capacity. Since the implementation of the current ocean dumping permit plan in 1973, 77 such disposal areas have been designated to receive dredged material. Although these disposal areas are widespread along the US coastline, very little is known of their impact on surrounding benthic communities. The effects of dredged material disposal on benthic communities depend upon volume and characteristics of the disposed sediment, oceanographic conditions at the disposal site, time of year, types of organisms inhabiting the disposal area and the presence of toxic substances in the dredged material (Van Dolah et al., 1984; Smith and Rule, 2001). Benthic communities at the disposal site inevitably suffer from complete burial, and biological recovery * Corresponding author. Tel.: +1 843 953 9092; fax: +1 843 953 9820. E-mail address: [email protected] (S.E. Crowe). 0025-326X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2009.12.007

of the new bottom habitat may take from a few weeks to many years (Cruz-Motta and Collins, 2004). Deposited dredge material may also be eroded and transported off the deposition site by oceanic currents. As a result, biological communities in areas surrounding disposal sites potentially are subjected to impacts. Documented biological impacts range from burial of infaunal communities by migrating fine sediments (McCauley et al., 1977) to reductions in the diversity and abundance of fish following the direct burial of hard bottom habitats (Lindeman and Snyder, 1999). In some areas, such as the Charleston (South Carolina, USA) ODMDS, dredged sediment deposition and migration has the potential to impact surrounding hard bottom reef habitats. These rocky formations support dense assemblages of sponges, corals, and other invertebrates (SAFMC, 1998a) and attract many recreationally and commercially important fishes such as black sea bass, porgies, snappers, and groupers (SCWMRD, 1984). Sediment migration has been documented outside the Charleston ODMDS (Gayes et al., 2002; Jutte et al., 2001; Noakes, 2001, 2003; Noakes and Jutte, 2006). Due to the proximity of the Charleston ODMDS to hard bottom reef habitats, there is the potential for long-term loss of sessile biota and associated finfish as this material migrates from the ODMDS. Studies on corals in the vicinity of the disposal site have already documented deleterious effects on short-term productivity and long-term abundances and recovery of these living hard bottom habitats following exposure to increased sediment loads (Porter, 1993). The current study was initiated to determine

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whether dredge material deposition at the Charleston ODMDS resulted in changes in sediment depth over the hard substratum, surficial sediment composition, sediment accumulation rates, sponge/ coral density, finfish assemblages and areal extent of hard bottoms at nearby hard bottom reef areas over a five-year period. This represented part of a larger study also evaluating changes in sediment mobility and transport, surficial sediment chemistry, benthic macrofaunal assemblages, and contaminants in the Charleston ODMDS and surrounding areas (Jutte et al., 2001, 2005; Noakes and Jutte, 2006; Voulgaris, 2002; Zimmerman et al., 2003).

2. Methods 2.1. Study area The ODMDS in Charleston, South Carolina, was designated by the USEPA in 1987 and is currently used by the United States Army Corps of Engineers (USACE) to receive both maintenance and deepening material from projects in the Charleston Harbor. The deepening of shipping channels throughout Charleston Harbor was completed in April 2002 and placed an estimated 1.7  107 m3 of material in the Charleston ODMDS, which is approximately seven miles from shore and is located within a much larger ODMDS that was originally established for the Charleston area and surveyed in 1978 (SCWMRD, 1979; Van Dolah et al., 1983). An additional 1.2  106 m3 of entrance material was deposited at the site from December 2003 through March 2004 (Noakes and Jutte, 2006). The current ODMDS overlaps another smaller ODMDS that was established for the placement of maintenance material. In an effort to minimize movement of dredged material from the ODMDS to nearby hard bottom sites, the USACE constructed a berm surrounding the ODMDS composed largely of Cooper marl material. The berms were first constructed on the southern and western borders of the ODMDS since those borders were closest to the hard bottom reef areas of concern. However, the efficacy of these mounds is unknown, especially as the fill volumes within the ODMDS approach the upper limits of the berm profile, and the berms slump and consolidate over time. A study investigating disposed material mobility and transport in the vicinity of the Charleston ODMDS found that transport direction appears to be parallel to the direction of the main western berm, therefore questioning the effectiveness of that berm in trapping sediment (Voulgaris, 2002). Hard bottom reef habitats are present within 4 km to the west of the disposal area, and have been identified in many other areas offshore of Charleston, South Carolina (SEAMAP-SA, 2001). A baseline monitoring study initiated in 1987 discovered hard bottom reef habitats near the historically used ODMDS area, resulting in that ODMDS being de-designated and moved to its current location further offshore (Winn et al., 1989). Since then, additional hard bottom habitats in the areas surrounding the ODMDS have been reported (Jutte et al., 2003).

Water quality data were collected at all reef sites using a YSIÒ Model 85 water quality meter to obtain surface and bottom measurements of dissolved oxygen, temperature, and salinity. Temperature, salinity, and dissolved oxygen values were similar among sites and seasons and were within typical levels for coastal South Carolina waters. With the exception of salinity, which varied by 2–3 ppt between surface and bottom waters, little stratification was apparent during either fall or spring at any of the sites (Crowe et al., 2006). 2.2.1. Large scale reef assessment Broad patterns in reef distribution and temporal change were investigated using simultaneous underwater video tows and detailed sidescan-sonar surveys of the six hard bottom reef sites. Initially, a comprehensive evaluation of geophysical data (mainly collected by US Geological Survey – Woods Hole in 2000) was the first in a series of studies that investigated the spatial characteristics of the reef sites near the ODMDS; these provided a categorized map of hard bottoms over the entire surveyed area (Gayes, 2001). Subsequent annual surveys and analyses were performed between February and April through 2005 using the R/V Coastal and R/V Nancy Foster. At each site, 1 km2 of seafloor was surveyed along eleven north– south and two east–west trending tracklines each year. Trackline data included: sidescan-sonar, bottom video, audio, and position. The sidescan system used for all surveys was a Klein 595 dual-frequency analog system, which is capable of collecting continuous backscatter data of the seafloor at frequencies of 100 and 384 kHz. A swath of 200 m in the athwart ship direction was ensonified with each pulse of the system’s transducers. By mosaicking the sidescan data along all shiptracks over each site, complete coverage of each square-kilometer was achieved, with significant data overlap (as much as 50%) between lines. Bottom video data were collected simultaneously and along the same track lines as the sidescan-sonar using a towed video array collection system. This custom-designed system consisted of four components: (1) an aluminum sled designed to slide on the bottom in an upright position at all times, (2) a water proof capsule containing two small surveillance cameras (black-and-white and color) mounted on the sled and aimed at the bottom at a 30° angle from horizontal, (3) a cable that transmits the video information from the cameras to the onboard laboratory, and (4) two sets of standard video cassette recorders for collection of data onto video tapes, one of which received a time stamp for further georectification. For this study, sidescan-sonar and bottom video track lines were spaced 100 m on average. The shiptrack deviated from a straight line in the center of each survey site in order to avoid collision of the video sled with anchored bottom benthic sampling gear (see Section 2.2.2) at the sites. The position of the ship’s global positioning system (GPS) antenna was logged at all times using HYPACK navigation software, at rates of approximately 2 Hz. These positions were further corrected for the layback between the GPS antenna and the positions of the sidescan-sonar vehicle and video sled.

2.2. Field methods Previous studies found that the bulk of sediment movement from the ODMDS was in the westward direction (Voulgaris, 2002; Williams et al., 1997). Potentially impacted hard bottom habitats were identified in the expected direction of sediment transport from the ODMDS (west) and were designated as ‘‘downdrift” reef sites (D1, D2, D3 in Fig. 1). Reef sites to the east of the ODMDS were considered less likely to be impacted by sediment movement from disposal activity and were designated as ‘‘reference” reef sites (R1, R2, R3 in Fig. 1).

2.2.2. Small scale reef assessment A more focused assessment of each reef site was performed by SCUBA to confirm the results of the sonar and video surveys and to provide more detailed examination of benthic conditions over the 2000–2005 time period. At each site, permanent markers were placed with four radiating transect lines (20 m) extending from a central marker at roughly 90° angles in an ‘‘x” pattern. Transect lines were repaired or replaced as needed when deterioration, damage, or fouling occurred. Each site was sampled in the spring and fall of each year to assess physical and biological conditions.

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Ch

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D1 Charleston ODMDS !

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D2

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0 79°50’0"W

2.5

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5 79°40’0"W

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Fig. 1. Location of hard bottom reef sites established during the first year of the study. Charleston ODMDS is represented by the solid black square. Arrow shows the dominant direction of sediment movement (Williams et al., 1997). Solid circles represent downdrift study sites, open circles represent reference sites.

Sediment cores (3.5 cm diameter) were used to collect the top layer (2.5 cm) of sediments at 5, 10, and 15 m from the central marker along each of the four transects at each site. Upon return to the surface, each core was placed in a pre-labeled plastic bag, kept on ice for transport to the lab, and stored in a freezer ( 20°) until analysis. Concurrent with sediment core collection, surficial sediment depth was measured to the nearest 0.5 cm by inserting a stainless steel ruler into the sediment until it hit hard substratum adjacent to the 5, 10, and 15 m interval marker on each transect line. Sediment traps were deployed during each sampling period at all sites. Each trap had a length of 46 cm, an inside diameter of 5.8 cm, a length-to-width ratio of 7.9, and was equipped with a baffle system of approximately nine smaller tubes (length 7.5 cm) inserted in the top of the tube. Open cylinders with a length-to-width ratio of approximately two or greater have been found to yield representative measurements of sedimentation (Knauer et al., 1979). The use of baffles to slow down circulation within the sediment trap allows particles to settle, making the trap a more efficient collector (Gardner, 1980a, 1980b; Honjo et al., 1992). Traps were placed near the center of each site with the distal end approximately one meter above the seafloor. From fall 2000 through spring 2002, a single trap was deployed at each site. Beginning in fall 2002, two to three replicate traps were deployed at each site. In addition to vertical deposition of sediments, redistribution of bottom sediments may make

some contribution to the total volume within a sediment trap. Therefore, volume measures from sediment traps are considered to be rough estimations of sediment accumulation from the water column. The material collected in each trap was used to quantify the relative accumulation rates of sediment and the silt/clay fraction. In order to examine changes in composition and abundance of fish and sponge/coral communities over time, underwater video surveys were performed by divers at each site. During each sampling period, two video surveys were recorded along each of the four transects. The first survey was completed with the camera held parallel to the seafloor (horizontal surveys), followed by a second transect with the camera held perpendicular to the seafloor (vertical surveys). Every effort was made to ensure consistency in video collections despite day to day variability in light quality and weather conditions. Two divers were trained in video collection to maintain consistency in swimming speed and distance of the camera from the transect line. 2.3. Laboratory methods 2.3.1. Sidescan-sonar processing Raw sidescan-sonar data were processed following the protocols in Danforth (1997). Individual lines collected over each reef site were then pieced together to produce sidescan-sonar mosaics,

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that were equivalent to top-view images of the seafloor. The mosaics were sampled at a 2 by 2 m cell size. The digital mosaics were stored in tagged image file format (TIFF), which was registered to Universal Transverse Mercator (UTM) coordinates by means of an associated world file and displayed as a GIS with ArcMap (ESRI). 2.3.2. Video coding Black-and-white and color videotapes were coded using the protocols described in Ojeda et al. (2001). Videos were coded by stopping the video tape every 5 s and describing the field of view captured in the frame according to the codes in Table 1. Because ship speeds ranged between 4 and 5 knots (2–2.6 m/s) during data acquisition, the spacing between coded points ranged between 10 and 13 m. To compare video data from all surveys, only video points that fell inside the 1.0 km2 box centered on each reef site were considered and counted. Point counts of the video record detailing each bottom type (at five second intervals) were performed using built-in functions in ArcGIS software and Excel spreadsheet software. 2.3.3. Textural analysis mapping of habitat A methodology for thematic mapping of seafloor habitats based on sidescan-sonar mosaics was developed during a study of nearshore reef sites adjacent to the Grand Strand Nourishment Project (Ojeda et al., 2001, 2004), a complete discussion of which can be found in Ojeda et al. (2004). Briefly, a video camera system is deployed on a bottom sled dragged behind the vessel while simultaneously deploying a sidescan-sonar system to quantify the acoustic signal of various substrate types. Several transects are made through each site to obtain data on the sidescan signature that corresponds to hard bottom habitat with and without sessile bottom growth, compared to sand bottom habitat with no growth. Using this approach, a distinct sidescan signature is obtained for each

habitat type that consistently and accurately reflects when the video sled is over each habitat type. This technique worked well in previous studies of nearshore habitats and presents one among few alternatives for the problem of generating spatially comprehensive, thematic maps of the seafloor (Gayes et al., 2002; Ojeda et al., 2001, 2004). For this study, the algorithm implemented for the Grand Strand study (Ojeda et al., 2001) was utilized. This algorithm produces only two possible outcomes from a given sidescan-sonar image or image window: sand and hard bottom. Because this algorithm was developed based on a high-quality mosaic and simultaneously acquired bottom video, it was deemed appropriate to continue employing this algorithm for consistency with the 2001 study (Gayes et al., 2002). 2.3.4. Preparation of change maps Interpretive raster maps obtained with the textural analysis routine were used to evaluate bottom change by making comparisons on a pixel by pixel basis between consecutive years. This allowed the construction of change maps on which each pixel was coded as (1) remained as sand, (2) remained as hard bottom, (3) changed from hard bottom to sand, or (4) changed from sand to hard bottom. The extent of a change map is limited to the overlapping area of the two input maps and thus contains values only on areas where both input maps hold data. Consequently, a fifth ‘‘no data” coding was possible, resulting from those areas of no data on at least one input map. 2.3.5. Sediment core and trap processing Sediment analyses were performed using a modification of the method described by Plumb (1981). Each sample was thawed and thoroughly homogenized, and a 20 g subsample was removed for particle size analysis. Twenty ml of a dispersant (sodium

Table 1 Classification scheme used to interpret video and audio data from the area surrounding the Charleston ODMDS. The bottom classification was coded for each 5-s length of video collected, merged with navigation from the HYPACK and overlain on sidescan-sonar mosaics using ArcMap. Bottom classification

Video characteristics

Audio characteristics

Bottom visible: Sand with no growth

Continuous sand veneer visible on the video

Low noise or constant abrasive noise

Bottom visible: Hard bottom that does not support soft corals and sponges

Clear outcrop of rocky substrate evident on the video but no visible invertebrate growth

Mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate

Bottom visible: Patchy emergent growth

Rocky substrate clearly visible on the video. Soft corals and sponges evident but less than 10 individual clusters observed per 10 s length of video

Mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate

Bottom visible: Heavy emergent growth

Rocky substrate clearly visible on the video. Soft corals and sponges evident and more than 10 individual clusters observed per 10 s length of video

Mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate

Bottom not visible: No emergent growth

The sea floor was not visible but suspended sediment and materials in the water column were still resolvable. No invertebrates observed within the field of view per 10-s length of video

Low noise or constant abrasive noise

Bottom not visible: Patchy emergent growth

The sea floor was not visible but suspended sediment and materials in the water column were still resolvable. Less than ten clusters of invertebrates were observed within the field of view per 10-s length of video

Mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate

Bottom not visible: Heavy emergent growth

The sea floor was not visible but suspended sediment and materials in the water column were still resolvable. More than ten clusters of invertebrates were observed within the field of view per 10-s length of video

Mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate

No visibility

Neither the bottom nor material in the water column is visible

Audio is classified as (1) low noise, (2) sound of sand abrading the sled, (3) mixture of sound of sand abrading sled and distinct collisions of sled on rocky substrate or (4) extensive collision of sled on rocky substrate

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2.3.6. Video survey review Video surveys obtained by SCUBA from each season were reviewed in the laboratory to assess abundance of sponges, corals, and finfish from the reef sites. Videos from each season were reviewed by the same invertebrate biologist to ensure consistency in data collection. Invertebrate video surveys (vertical surveys) were subdivided into 10-s intervals for analysis. Presence/absence was recorded during each interval for massive sponges including Ircinia sp., and the soft corals Leptogorgia sp. and Titanideum sp. In addition, if one or more of these organisms was present, that particular interval was also recorded as having hard bottom reef habitat present. At each site, finfish counts were generated separately for both horizontal (n = 4 per sampling period) and vertical surveys (n = 4 per sampling period). The number of observed fish families and the abundance of fish along each transect was determined. 2.4. Data analyses 2.4.1. Large scale reef assessment Changes that occurred in bottom habitat during the periods July 2001 to October/November 2002, October/November 2002 to February 2004, February 2004 to March/April 2005, and July 2001 to March/April 2005 were characterized in two different manners: by comparing coded video points from the two survey seasons, and by applying the textural analysis technique described in Ojeda et al. (2004). Sidescan-sonar data, video data, textural analysis mapping, and habitat change map data presented here were condensed from more detailed information presented in Crowe et al. (2006). 2.4.2. Small scale reef assessment Repeated-Measures Analysis of Variance (RMANOVA) with ‘‘Group” (downdrift or reference) and ‘‘Site” (D1–D3 or R1–R3) nested within group as factors and ‘‘Time” as a covariate was used to examine changes of downdrift and reference reef sites over time. A significant Group  Time interaction term would indicate the downdrift and reference sites were changing differently through time, potentially reflecting the effects of migrating dredge material on the downdrift sites. Because sediment trap data were already in the form of a rate, the Group term in the model would indicate the downdrift and reference areas were changing differently for these parameters. Prior to analysis, values for each of the sediment parameters were averaged within each transect then across

transects during a sampling event at each site. Sediment trap data were treated similarly prior to analysis, but spring and fall were analyzed separately due to expected seasonal variation. The percent of 10 s intervals in which each invertebrate taxon (Titanideum, Leptogorgia, massive sponges, and any hard bottom) was present in the video within each transect was calculated and then averaged across transects within each site during each time period. Fish community data were treated similarly to the invertebrate data, but the spring and fall seasons were analyzed separately. All data were transformed as needed to satisfy the assumptions of normality and homogeneity of variance and analyzed using Minitab 12.5 (Minitab, Inc.). 3. Results 3.1. Large scale reef assessment At larger spatial and temporal scales, the textural analysis indicated there was no consistent change in the percent of bottom classified as hard bottom habitat in either the reference or downdrift groups between 2001 and 2005 (Fig. 2). The temporal variability in hard bottom area, especially in the downdrift group, did not exhibit clear trends. While the reference group generally increased slightly in the amount of hard bottom habitat, the downdrift group increased between 2001 and 2002 and then decreased during later years (Fig. 2). The percent of the seafloor that changed from one habitat type to another (sand to hard bottom or hard bottom to sand) was much greater than was apparent from the changes in total amounts of hard bottom described above. While it was expected that sediments transported from the ODMDS could cause more changes in habitat types in downdrift sites than in reference sites, the reference group showed consistently higher percentages of habitat change than the downdrift group (Fig. 3A). The amount of hard bottom shifting to sand was generally greater in the downdrift group, but the change was not significantly different from the reference group in any time period (Fig. 3B). Between 2001 and 2002, this pattern was reversed, with the reference group having significantly more habitat change to sand. The reference group consistently had more habitat change from sand to hard bottom than did the downdrift group (Fig. 3C), a difference that accounted for much of the difference in total habitat change (Fig. 3A) between the reference and downdrift groups.

90

Downdrift Reference

Sonar Hard Bottom (%)

hexametaphosphate) solution was added to the subsample. The subsample was then wet sieved through a 63-lm stainless steel sieve using distilled water. The filtrate was collected in a 1000 ml graduated cylinder for pipette extraction of the fine component (silts and clays). The material retained on the sieve (sand and CaCO3) was dried at 90 °C to obtain a total dry weight. This material was then subjected to 10% HCl and 550° incineration to eliminate CaCO3 and organic matter respectively. The remaining sand was dry-sieved using a Ro-tap mechanical shaker and sand grain size was determined using fourteen 0.5 phi-interval screens, where phi = log2 (grain diameter in mm) according to the Udden-Wentworth Phi classification (Brown and McLachlan, 1990). Data from sediment cores were summarized as percent of the sample mass comprised of silt and clay, sand and CaCO3 and the grain size (phi) of the sand fraction. The mass of total sediment in the traps was divided by the number of days the trap was deployed in order to calculate a rough sedimentation rate. This sedimentation rate was multiplied by the proportion of the sediment represented by silt and clay in order to calculate a silt/clay accumulation rate.

80

70

60

50

F 2000

S

F

2001

S 2002

F

S

F

2003

S

F

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S 2005

Fig. 2. Percent of sonar hard bottom detected by textural analysis during each year (fall and spring sampling events) at downdrift and reference sites over during the monitoring study.

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50

A

30

Downdrift

B

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Hard Bottom to Sand (%)

Total Habitat Change (%)

Reference

30

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C Net Hard Bottom Change (%)

Sand to Hard Bottom (%)

30

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2001-2002

2002-2004

2004-2005

2001-2005

D

20

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0

-10

-20

2001-2002

2002-2004

Time Period

2004-2005

2001-2005

Time Period

Fig. 3. Percent of seafloor change over time as indicated by textural analysis including: (A) total habitat, (B) hard bottom to sand, (C) sand to hard bottom, and (D) net hard bottom.

Reference

3.2. Sediment characteristics

3.2.2. Sediment composition Sand was the predominant sediment type at all sites, with site averages ranging from 57.4% to 89.9%. Calcium carbonate was the second largest component (7.6–39.5%), and sites that had less sand content generally had CaCO3 instead of silt/clay as the bulk of the remaining sediment. In general, silt/clay was a minor component of the sediment at all sites with the maximum silt/clay content being 5.5% at site D1 during year 2. Sediment composition showed an overall trend of significantly decreasing CaCO3 and increasing sand and silt/clay content, with reference and downdrift groups changing similarly through time (Table 2; Fig. 5A–C). While the downdrift group tended to have lower sand and higher silt/clay content than the reference group (Fig. 5A–C), these differences were not significant due to substantial

Downdrift

12.0 Sediment Depth (cm)

3.2.1. Surficial sediment depths Average surficial sediment depths ranged from 1.9 to 14.4 cm during all sampling periods. Over the five years of the study, average sediment depth over the hard bottoms increased slightly in the downdrift group and decreased slightly in the reference group (Fig. 4) but the difference in response between the two groups was not significant (Group*Year interaction in Table 2). There was marginally significant site-to-site variation within groups over time, and sites within the groups changed differently through time (Table 2).

14.0

10.0 8.0 6.0 4.0 2.0 0.0

F 2000

S

F

2001

S 2002

F

S

F

2003

S

F

2004

S 2005

Fig. 4. Mean sediment depth collected during each year (fall and spring sampling events) at downdrift and reference sites over the five-year monitoring period.

variability among the sites within downdrift and reference groups (Table 2). The mean phi size of the sand fraction increased slightly (became finer) in the downdrift group and stayed the same in the reference group (Fig. 5D), but this difference in response of the two groups was not significant (Table 2). However, the sites within

S.E. Crowe et al. / Marine Pollution Bulletin 60 (2010) 679–691 Table 2 Results of repeated measures ANOVA comparing physical characteristics at downdrift and reference sites throughout the five-year study period. Source

df

Sediment depth Group Site (Group) Year Group*Year Site*Year Error

F

P

1 4 1 1 4 47

0.88 2.33 0.87 0.34 2.68

0.400 0.070 0.357 0.563 0.043

Sand Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 46

0.00 45.42 7.87 0.00 1.76

0.997 0.000 0.007 0.999 0.154

CaCO3 Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 46

0.06 59.20 11.62 0.89 2.13

0.813 0.000 0.001 0.349 0.093

Silt/clay Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

3.28 2.02 5.75 1.26 0.83

0.145 0.107 0.020 0.268 0.513

Phi size Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

0.67 17.69 0.29 1.18 3.69

0.458 0.000 0.594 0.283 0.011

groups were significantly different in phi size and changed significantly differently over the course of the study (Table 2, Fig. 5D). Although not significant, phi size values were substantially higher (indicating finer sands) at reference sites than downdrift sites (Fig. 5D). 3.2.3. Sediment traps The downdrift group had a higher sediment accumulation rate than the reference in both seasons of all years of the study (Fig. 6A and B), but overall the downdrift group had a significantly higher sediment accumulation rate only during the fall (Table 3). During the spring, sites within the downdrift and reference groups differed significantly (Table 3), likely contributing to the difficulty detecting a consistent difference between the groups. In general, sediment accumulation rates were increasing over the five years of the study period, and in fall, sediment accumulation rates were increasing significantly faster in the downdrift group than in the reference group (Table 3). The downdrift group had a significantly higher silt/clay accumulation rate than the reference in both seasons overall (Table 3), and the downdrift group had higher silt/clay accumulation rates in both seasons during every year of the study (Fig. 6C and D). During the spring, sites within the downdrift and reference groups differed significantly (Table 3). 3.3. Video survey data 3.3.1. Invertebrate surveys Over the five years of the study, the amount of hard bottom reef present decreased significantly overall with reference sites

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decreasing at a faster rate (although not significantly) than downdrift sites (Table 4; Fig. 7A). There was also a significant difference in the amount of hard bottom between sites within the groups. Of the invertebrate taxa surveyed, the gorgonians Leptogorgia changed significantly and Titanideum marginally differently through time at downdrift and reference sites (Table 4). Leptogorgia cover and cover of massive sponges increased in the downdrift group while decreasing slightly at the reference group (Fig. 7B and D); cover of the soft coral Titanideum decreased in both groups but somewhat faster in the reference group (Fig. 7C). Titanideum cover and cover of massive sponges differed significantly between sites within the downdrift and reference groups (Table 4).

3.3.2. Finfish surveys The most common fish observed included serranids (black and bank sea bass), sparids (scup, sheepshead), labrids (slippery dick), and haemulids (tomtate). Mean abundances of fish varied from zero to 82 individuals per transect during both horizontal and vertical surveys. The number of families varied from zero to five families per transect. Finfish abundance and family-level richness did not change significantly differently at the downdrift and reference groups during either season, with the exception of a marginally significant difference in the change of abundance measured in horizontal surveys during the fall (Table 5). Finfish abundance and family-level richness did show evidence of varying through time and among sites within the reference and downdrift groups, particularly in the horizontal surveys (Table 5). In general few differences were found among the two groups of sites with the exception of slightly (although not significantly) greater increases in finfish abundance in horizontal surveys during both season (Fig. 8).

4. Discussion This study provided little evidence to suggest that proximity to the Charleston ODMDS significantly affected hard bottom reef habitats during the five-year monitoring program. Assuming large enough volumes of sediment were migrating from the ODMDS, downdrift sites were expected to respond with increased sediment accumulation, decreased hard bottom habitat, and decreased invertebrate and finfish densities as compared to reference sites. The large scale surveys indicated that the downdrift and reference groups as a whole experienced similar rate of habitat change with both groups having a net gain of hard bottom habitat. The smallerscale surveys confirmed that the physical and biological characteristics of the downdrift and reference groups responded similarly over the course of the study. Bottom habitat changes that occurred during the inter-survey periods were characterized by comparing coded video points from each of the two survey seasons, and by applying the textural analysis technique described in Ojeda et al. (2004). The textural analysis technique is entirely raster-based and allows comparisons to be made at a pixel basis over the entire survey area. While the spatial coverage is complete with this technique, many bottom characteristics can affect backscatter intensity. It is possible, for example, to have a thin veneer of sand over an area, yet still have high backscatter intensity values. Ground truthing with audio and video data provides a higher level of confidence in bottom type classification relevant to benthic habitat condition. The audio and video data are, however, limited spatially to the relatively narrow field of view along the survey transects. It is best, therefore, to employ a combination of these methods for the most complete and accurate characterization of bottom type. Comparisons between backscatter intensity, textural analysis, and coded video data suggest that a

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90

40

A

B

35

CaCO3 (%)

Sand (%)

80

70

30 25 20

60

Reference

15

Downdrift

10

50 7

C

3.5

D

6

Sand Phi Size

Silt/Clay (%)

3.0 5 4 3

2.5

2.0

2 1.5

1 0 F 2000

S

F

2001

S

F

2002

S

F

2003

S

F

2004

S 2005

1.0

F 2000

S

F

2001

S

F

2002

S

F

2003

S

F

2004

S 2005

Fig. 5. Average percent of sand (A), CaCO3 (B), silt/clay (C), and mean phi size of the sand fraction (D) from sediment core samples during each year (fall and spring sampling events) at downdrift and reference sites over the five-year monitoring period.

thin veneer of sand is sometimes capable of disguising hard bottom, but not always detrimental to sessile benthic ecosystems. The sediment traps at each hard bottom reef site collected material representative of the sediments in the water column, as well as fine sediments being redistributed from the seafloor. Downdrift sites in the vicinity of the disposal area generally had higher accumulation of sediment than reference sites, and in most cases a similar trend was observed with respect to percent silt/clay. However, in year 5, there were elevated silt/clay levels at downdrift and reference sites, and in some cases the highest recorded values were observed at reference sites. Most likely this trend reflects increased turbulence in the water column and on the seafloor as a result of the above average hurricane and tropical storm activity experienced in the southeast United States in the fall 2004. In this study, there was little consistent change over time with respect to sediment depth or sediment characteristics. In general, an associated increase in sediment depth or silt/clay content was not observed at downdrift sites relative to reference sites, which suggests that more sediments are moving through the sites rather than accumulating. In general, silt/clay was a minor component of sediment composition at all sites and any changes observed were probably attributable to seasonal rainfall or storm activity rather than significant movement of fine-grained material from the ODMDS. Silt/clay content tended to be higher at downdrift sites than reference sites which may be because they are closer to shore than the reference sites and therefore subjected to more natural sources of variability. Previous benthic assessments around the Charleston ODMDS have shown evidence of sediment migration (Jutte et al., 2001, 2005; Van Dolah et al., 1996, 1997; Zimmerman et al., 2003).

Zimmerman et al. (2003) noted significant alterations of sediment characteristics, particularly silt/clay content and organic matter content, relative to typical conditions found in South Carolina’s nearshore zone. It was determined that a number of physical and biological impacts to the areas surrounding the Charleston ODMDS resulted from the placement of material into the disposal zone from the Deepening Project, and from ongoing maintenance dredging (Jutte et al., 2005). Several factors may have influenced the change in sediment characteristics including the migration of dredged material from the disposal site, unauthorized dumping outside the designated site, and trailings from barges entering or exiting the disposal area. In a companion study utilizing gamma isotope tracers to determine sediment source at the hard bottom reef sites surrounding the Charleston ODMDS (Noakes and Jutte, 2006), it was concluded that the sediment budget at sites D1, D2, D3, and R3 may be influenced by density driven sediments with tidal and/or disposal area origins. Hard bottom reef areas monitored in this study may be far enough away that impacts from migrating material are minimal; however, long-term effects could still be a cause for concern as material continues to accumulate in the disposal area and migrate out. The temporary increases and decreases in sediment depth and characteristics observed at some sites during the study period are more likely due to natural events related to storm activity and tidal currents. Downdrift site D1, where the highest overall average surficial sediment depth was recorded, is the closest study site to the Charleston Harbor entrance channel and is located to the west of the ODMDS. Bottom current studies (Williams et al., 1997) indicate the possibility of sediment movement from the ODMDS in this direction, but it is not the predominant direction of currents,

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Fall Sediment Accumulation (g/day)

8

Downdrift Reference

7

B

7

6

6

5

5

4

4

3

3

2

2

1

1

0

0

8 Silt/Clay Accumulation (g/day)

A

Spring 8

8

C

7

7

6

6

5

5

4

4

3

3

2

2

1

1

0

D

0 2000

2001

2002

2003

2004

Average

2001

2002

2003

2004

2005

Average

Fig. 6. Summary of total sediment accumulation rate (A and B) and silt/clay accumulation rate (C and D) in sediment traps during fall and spring sampling seasons of all years of the study.

Table 3 Results of repeated measures ANOVA comparing sediment trap data at downdrift and reference sites seasonally throughout the five-year study period. Source

Fall df

Spring F

P

df

F

P

Total sediment (g/day) Group 1 Site (Group) 4 Year 1 Group*Year 1 Site*Year (Group) 4 Error 18

1.16 2.09 0.97 0.43 0.86

0.342 0.124 0.338 0.519 0.509

1 4 1 1 4 16

7.10 1.30 0.95 0.32 0.64

0.050 0.311 0.345 0.577 0.642

Silt/clay (g/day) Group Site (Group) Year Group*Year Site*Year (Group) Error

8.01 1.16 0.03 0.82 0.65

0.047 0.359 0.876 0.378 0.632

1 4 1 1 4 16

6.97 2.86 0.22 3.56 0.6

0.054 0.058 0.642 0.078 0.667

1 4 1 1 4 18

which primarily flow to the southwest (Voulgaris, 2002). Site D1 is also potentially affected by the Charleston Harbor sediment plume, and was the only site in the study by Noakes and Jutte (2006) where tidally transported sediments were found. Additionally, reference site R1 showed an increase in sand content of almost 20% from fall 2004 to spring 2005, which correlates with a particularly wet month prior to spring 2005 sampling (7.24 inches of rainfall recorded in March 2005 according to data collected at the Marine Resources Research Institute at Fort Johnson, South Carolina). The

additional rainfall may have caused shifting sands at the reference site. It is unlikely that site R1 was affected by sediments migrating out of the ODMDS since the site is about six miles to the northeast of the disposal area. Any of these factors could be a result of the proximity of these areas to the disposal area and/or the deposition of fine-grained materials entering the nearshore system as a result of tidal flow from Charleston Harbor. Over the five years of sampling conducted, little evidence of impact on sessile invertebrates and fish communities associated with hard bottom habitats was found. The sites located near the disposal area do not appear to have lost significant overall reef habitat, particular species of soft corals, or sponge morphotypes. In many cases, the percent of reef habitat is greater at sites near the disposal area than at reference sites; these differences appear to represent dissimilarities in abundance and composition of invertebrates among sites that have existed throughout the study and are not likely related to disposal activities. There is a similar or greater amount of decline in hard bottom habitats at the reference sites when compared the downdrift sites which indicates that degradation of hard bottom habitat is not necessarily occurring due to disposal material migrating from the ODMDS. This assumes that the reference sites were beyond the realm of influence from the ODMDS, which we believe is a reasonable assumption based on other study components (Crowe et al., 2006). The presence of massive sponges and the soft corals Titanideum and Leptogorgia were highly variable through time and between sites. Since abundances at reference sites were declining significantly faster than downdrift sites, it is unlikely that the trend is a

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Table 4 Results of repeated measures ANOVA comparing invertebrate and hardbottom densities at downdrift and reference sites throughout the five-year study period. Source

df

F

P

Hard bottom Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

0.61 3.67 19.82 2.01 0.37

0.478 0.011 0.000 0.162 0.831

Titanideum Group Site(Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

0.10 4.37 14.08 3.06 0.57

0.762 0.004 0.000 0.087 0.683

Leptogorgia Group Site(Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

3.98 0.70 1.60 9.43 1.43

0.117 0.597 0.213 0.004 0.239

Massive porifera Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 48

4.58 0.40 0.05 0.23 0.98

0.579 0.040 0.187 0.415 0.648

Source

Fall

Spring

df

F

P

df

F

P

Abundance (horizontal) Group 1 Site (Group) 4 Year 1 Group*Year 1 Site*Year (Group) 4 Error 17

0.88 0.26 9.05 3.2 1.34

0.402 0.901 0.008 0.091 0.297

1 4 1 1 4 18

1.04 0.59 3.01 1.34 0.56

0.365 0.671 0.100 0.261 0.694

Abundance (vertical) Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 17

4.41 0.17 0.37 0.56 0.28

0.104 0.952 0.549 0.466 0.887

1 4 1 1 4 18

0.80 1.69 1.55 0.07 1.58

0.420 0.197 0.23 0.798 0.221

Families (horizontal) Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 17

0.09 3.34 0.96 0.08 1.66

0.777 0.034 0.341 0.777 0.205

1 4 1 1 4 18

0.00 3.20 0.53 0.08 1.25

0.963 0.038 0.477 0.775 0.325

Families (vertical) Group Site (Group) Year Group*Year Site*Year (Group) Error

1 4 1 1 4 17

0.03 0.67 5.13 0.04 0.63

0.874 0.619 0.037 0.839 0.648

1 4 1 1 4 18

0.28 2.99 0.04 0.00 1.93

0.626 0.047 0.836 0.945 0.149

S

S

A

80

80

B

60

Titanideum (%)

Hard Bottom Habitat (%)

100

Table 5 Results of repeated measures ANOVA comparing fish densities at downdrift and reference sites seasonally throughout the five-year study period.

60 40

20

Reference

20

40

Downdrift

0 60

0 35

C Massive Sponges (%)

Leptogorgia (%)

50 40 30 20 10

D

30 25 20 15 10 5

0

0 F 2000

S

F

2001

S

F

2002

S

F

2003

S

F

2004

S 2005

F 2000

S

F

2001

S

F

2002

F

2003

F

2004

S 2005

Fig. 7. Average percent of video intervals with hard bottom (A), Titanideum (B), Leptogorgia (C), and massive sponges (C) present during each year (fall and spring sampling events) at downdrift and reference sites over the five-year monitoring period.

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80

A

No. Individuals (Horizontal)

70

50

40

40

30

30

20

20

10

10

0

0

No. Individuals (Vertical)

No. Families (Horizontal)

80

C

70

70

60

60

50

50

40

40

30

30

20

20

10

10

0

0 3.0

E

2.5

2.5

2.0

2.0

1.5

1.5

1.0

1.0

0.5

0.5

0.0

0.0

3.0

Spring

60

Downdrift

50

3.0

B

70

Reference

60

80

No. Families (Vertical)

80

Fall

3.0

G

2.5

2.5

2.0

2.0

1.5

1.5

1.0

1.0

0.5

0.5

D

F

H

0.0

0.0 2000

2001

2002

2003

2004

2001

2002

2003

2004

2005

Fig. 8. Average number of individual fish and fish families observed during horizontal and vertical video surveys at reference and downdrift sites during spring and fall sampling periods.

result of sediment migration from the ODMDS and may be a direct result of the sampling methods used. For example, during the sampling periods in fall 2002 and spring 2003, we noticed that some of the transect lines were possibly damaging soft coral specimens at the sites when being washed about by storm activity which may

have caused the decreased abundances. Also, dramatic increases in sponge populations were noted during certain seasons. Since the large sponge species present are slow growing, it is likely that these abundances were a result of misinterpretations from the video survey.

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The number of individual fish as well as the number of species observed at hard bottom reef sites may be affected by factors such as fishing pressure and hydrographic parameters (Sedberry et al., 1998). A study by Sedberry and Van Dolah (1984) examining fish assemblages in the South Atlantic Bight found that fish were more abundant on midshelf reefs (23–38 m) than inshore reefs (16– 22 m) during the warmer months, and attributed this to more stable hydrographic conditions. All sites examined in this study were quite variable throughout the monitoring period. Overall fish abundances (horizontal survey) increased at the reference sites while changing little at the downdrift sites. There was no trend in declining fish stocks over the five-year period that might reflect adverse effects from the disposal area. However, the monitoring technique used in this study has many limitations that may affect data quality, including low visibility, schools of fish which swim back and forth in front of the surveyor’s camera, and possible disturbance of fish by diver activity. Like all environmental impact assessments, inherent differences between study (downdrift) and reference sites can confound results. Our small sample size (3 study sites and 3 control sites) made detection of potential differences difficult. However, many environmental impact assessments rely on a single study and single reference site. The significant differences found here, which were consistently a result of site-to-site variation within a group (downdrift or reference), clearly indicate the danger in this approach. Faster, more focused assessment methodology is needed to allow the monitoring of a greater number of sites across the potential impact gradient.

5. Conclusion The findings presented here suggest that hard bottom reef areas surrounding the Charleston ODMDS showed little evidence of degradation resulting from possible movement of sediments out of the disposal area over the five-year monitoring period. Sidescan-sonar indicated that there was more change from hard bottom to sand at downdrift sites than reference sites although small gains or losses of hard ground during the inter-survey periods at each site suggest that only a small amount of mobile sediment, with a transient nature, is present in this area of the South Carolina inner shelf system. Sediment data indicated that there was more suspended sediment and fine material (silt/clay) at downdrift sites relative to reference sites, although these fines do not appear to be accumulating. While we did not find substantial evidence of impacts to any of the parameters we investigated, it should be noted that the inherent variability of the sites in this dynamic environment makes it difficult to detect subtle changes that may be occurring in the reef areas. Diver observations at discrete locations provide information on the presence or absence of erect sessile fauna that should be representative of the rest of the reef and can be accurately reassessed over time. However, the lack of baseline data at the hard bottom reef sites we investigated makes it difficult to determine if there were impacts from the disposal area prior to our monitoring study. In this study, downdrift sites were generally closer to the Charleston Harbor plume so some differences may reflect this influence. Additionally, the distance of hard bottom habitats from the Charleston ODMDS likely helps to reduce the impacts of sediment migration, but the longer term impacts are still a concern. Further monitoring should be considered in order to ensure that hard bottom reef habitats in the vicinity of the Charleston ODMDS continue to suffer limited, if any, harm from migrating sediments. Due to the uncertainty of how well the berms located on the boundaries of the Charleston ODMDS will continue to contain the dredged material, especially following major storm events,

periodic surveys including the index sites from the current study should be conducted in the future, especially after the passage of any named storm through the area. Acknowledgements The authors greatly appreciate the laboratory and field efforts of the following SCDNR and CMWS staff: Mike Arendt, Anne Blair, Steve Burns, Josh Chastain, Joe Cowan, Susan DeVictor, Cara Fiore, Leona Forbes, Jeff Jacobs, Josh Loefer, Bob Martore, Scott Meister, Nadia Meyers, Tammie Middleton, Dr. German Ojeda, Jamie Phillips, Paulette Powers-Mikell, George Riekerk, Angela Rourk, and Daryl Stubbs. Finally, we thank Robin Coller-Socha and Phil Wolfe with the US Army Corps of Engineers, Charleston District for their assistance and support throughout the project. The US Army Corps of Engineers funded these monitoring efforts through Cooperative Agreement SAC0007. This is South Carolina Marine Resources Division Contribution Number 658. References Brown, A.C., McLachlan, A., 1990. Ecology of Sandy Shores. Amsterdam, the Netherlands, Elsevier. Crowe, S.E., Van Dolah, R.F., Jutte, P.C., Gayes, P.T., Viso, R.F., Noakes, S.E., 2006. An environmental monitoring study of hard bottom reef areas near the Charleston Ocean Dredged Material Disposal Site. Final Report Submitted to the US Army Corps of Engineers. p. 121. Cruz-Motta, J.J., Collins, J., 2004. Impacts of dredged material disposal on a tropical soft-bottom benthic assemblage. Marine Pollution Bulletin 48 (3–4), 270–280. Danforth, W.W., 1997. Xsonar/ShowImage: a complete system for rapid sidescan processing and display. US Geological Survey, Open-File Report 97-686. p. 77. Gardner, W.D., 1980a. Sediment trap dynamics and calibration: a laboratory evaluation. Journal of Marine Research 38, 17–39. Gardner, W.D., 1980b. Field assessment of sediment traps. Journal of Marine Research 38, 41–52. Gayes, P.T., 2001. Geophysical characterization of the seafloor within the Charleston Ocean Dredged Material Disposal Site, March–September 2000. Submitted by the Center for Marine and Wetland Studies Coastal Carolina University, Conway, South Carolina 29526, to the South Carolina Department of Natural Resources, Marine Resources Division, Prepared under SC DNR PO 00 031975. Gayes, P.T., Ojeda, G.Y., Jutte, P.C., Van Dolah, R.F., 2002. Geophysical characterization of the seafloor: Charleston Ocean Dredged Material Disposal Site – July 2001. Final Report Prepared by the Center for Marine and Wetland Studies and the South Carolina Department of Natural Resources for the US Army Corps of Engineers, Charleston District. p. 54. Honjo, S., Spencer, D.W., Gardner, W.D., 1992. A sediment trap intercomparison experiment in the Panama Basin, 1979. Deep Sea Research 39, 333–358. Jutte, P.C., Levisen, M.V., Van Dolah, R.F., 2001. Analysis of sediments and habitats in the areas surrounding the Charleston Ocean Dredged Material Disposal Site, including unauthorized disposal operations. Final Report Submitted to the Norfolk Dredging Company and the US Army Corps of Engineers, Charleston District. p. 23. Jutte, P.C., Van Dolah, R.F., Crowe, S.E., Ojeda, G.Y., Gayes, P.T., 2003. Monitoring and assessment of natural hard bottom reef communities off South Carolina. In: Proceedings, Southeast Coastal Ocean Science Conference and Workshop, January 27–31, 2003, Charleston, SC. Jutte, P.C., Crowe, S.E., Van Dolah, R.F., Weinbach, P.R., 2005. An environmental assessment of the Charleston Ocean Dredged Material Disposal Site and surrounding areas: physical and biological conditions after completion of the Charleston Harbor deepening project. Final Report to the Charleston District, US Army Corps of Engineers. Kennedy, C.C., 2006. History of dredged material management and usage in the United States. In: Eighteenth World Congress of Soil Science, July 9–15, 2006, Philadelphia, Pennsylvania. Kester, D.R., Detchum, B.H., Duedall, I.W., Park, P.K., 1983. Dredged material disposal in the ocean. Wastes in the Ocean, vol. 2. John Wiley and Sons Press. p. 299. Knauer, G.A., Martin, J.H., Bruland, K.W., 1979. Fluxes of particulate carbon, nitrogen, and phosphorus in the upper water column of the northeast Pacific. Deep Sea Research 26A, 97–108. Lindeman, K.C., Snyder, D.B., 1999. Nearshore hard bottom fishes of southeast Florida and effects of habitat burial caused by dredging. Fishery Bulletin 97, 508–525. McCauley, J.E., Parr, R.A., Hancock, D.R., 1977. Benthic infauna and maintenance dredging: a case study. Water Research 11, 233–242. Noakes, S., 2001. Postdisposal areal mapping of sediment chemistry at the Charleston, South Carolina ODMDS, Center for Applied Isotope Studies, Athens, GA. Submitted to South Carolina Department of Natural Resources, Under SC DNR PO 01 030658.

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