20230570 Ver 1_CAMA Application_20230421 (18)

NCDMF Artificial Reef Program
Site Selection Report

Substrate Grabs and Side Scan/Multi-Beam Bathymetric Analysis for Proposed Mouse
Harbor/Pamlico Point -

Sampling and Data Processing by: Nick Hendrix, Trent Kennedy, Mason Ellis
Analysis, Report, and Maps Generated by: Nick Hendrix

Purpose
In recent months, there has been increased interest in constructing a new estuarine reef
-in the lower Pamlico River. NCDMF Artificial Reef staff completed site selection
efforts in order to both find a suitable site and to maximize the efficacy of the selected site
relative to usage and longevity. While many limitations apply for citing a suitable location, the
following are top physical and biological considerations which must be met: 1) Correct bottom
type (relatively hard and sandy vs soft and muddy, no existing hard or live bottom habitat, and
no seagrass); 2) Suitable depth range of 8-
standards of 6and to limit material being placed in deeper areas which may
experience seasonal and weather-driven anoxic events; and 3) Close proximity to recreational
boat ramps, with locations closer to boat ramps being preferred over locations farther from boat
ramps. Additional site selection protocols include details surrounding water quality (e.g., DO >
3.2mg/L), recreational and commercial vessel traffic on and around the site, proximity to
natural/artificial reefs, and proximity to stockpile sites for reef enhancement. Further details and
other considerations for suitable site selection can be found in NCDMF Habitat and
Site Selection protocols. Assumptions of reef construction and enhancement at
the proposed site are outlined in NCDMF Habitat and Enhancement SOPs and literature.

A general location of Mouse Harbor near the mouth of the lower Pamlico River
() was selected as a preferred area to investigate (Fig. 1). The specific site
selection area is centered on 35° 17.725' N, -76° 28.766' W. This area was initially selected
based upon the above listed DMF site selection protocols, NOAA navigation/LIDAR charts, and
general knowledge by local watermen familiar with the area. Two goals were accomplished by
NCDMF Artificial Reef staff in order to gauge the area as a possible reef site: 1) Patent tong
substrate grabs to identify sediment type and substrate stability (completed October 12, 2022)
and 2) Side scan imaging and multi-beam bathymetric scans of the area to validate and quantify
both depth and bottom type (completed January 4, 2023.)

Methods
A localized NOAA LIDAR map (Figure 2) along with nautical charts was used to locate
an area around Mouse Harbor/Pamlico Point as a possible reef location. Once the general
location was selected, a sampling map was created to obtain substrate grabs from the area and to
lay out a route with the side scan survey vessel.

There were 24 sample locations tonged and an additional four sample points investigated
for depth on October 12, 2022 (Figure 3).
hydraulic patent tongs to take substrate samples from pre-determined locations inside the

proposed reef area. The vessels bottom machine (Lowrance) was used to take depth
measurements. The patent tongs were used to grab full tong samples: samples included substrate
from the top of substrate down to approximately 2 feet into the substrate. The majority makeup
of the entire sample grab was noted (sand, mud, muddy sand, etc.) along with presence/absence
of oysters or seagrass. A photograph recorded each tonged sample and a data sheet was filled out
with the relative sample information.

On January 4, 2023 soat to take side scan and bathymetric
multi-beam scans of the area. Side scan post-processing was completed per the NCDMF side
scan SOP. Additionally, the multi-beam bathymetric scans taken were used to compare and
validate NOAA LIDAR charts as well as the bottom machine depths taken while tonging on
October 12.

Results
In total, 28 locations were sampled October 12, 2022. Twenty-four samples were tonged.
The majority of the tonged samples (16san
eight Sandy mud was more prevalent in the relatively
deeper (> 10.5 northern areas of the site while alent in the southern
end of the site in relatively shallower (< 10.5An additional four samples (Samples
25-28) were selected while in the field to gain further site data. Tong samples were not taken on
Samples 25-28 as the depths seen on the sampling boatbottom machine (<10ft) were not
suitable for reef construction. No oyster or seagrass were found to be present in any of the tonged
substrate samples. Example photographs of substrate are shown in Figure 4 and Figure 5.
Substrate sample results and field notes can be seen in Figure 6. Results of tong sampling can be
seen in Figure 7 showing sample ID, sampling vessel bottom machine depth, and substrate type.

Water quality taken on October 12 with YSI can be seen in Table 1 below. There is no
long-term water quality data available for the site.

Water Quality YSI TOP YSI Bottom

deep)

19.3 19.5
Temp (F)

25.6 27.3
Salinity (ppt)

10.0 8.89
DO mg/L

\[Table 1: Water quality taken with YSI while on tonging vessel October 12, 2022.\]

The side scan and multi-beam survey did not identify any existing shell, seagrass, or hard
bottom in the surveyed area. Side scan imagery (Figure 8) did not locate any notable objects
(sunken vessels, hard bottom, large ridges, etc.) Backscatter (Figure 9) shows relative substrate
relative only to the scanned area e.g., light colors do not necessarily mean hard bottom.
Backscatter results were compared with tong results in order to approximate backscatter RGB
values. Analysis of individual tong samples compared to relative backscatter values found that

the muddy sand or sandy mudis found site wide. These estimated hardness values
were then used to ascertain site-wide substrate type. Analysis suggests that the proposed reef site
is predominantly made up of a mixture of sand and mud with no hard bottom, shell, or sea grass
present in the proposed reef boundary.

As analysis of side scan, backscatter, and tonged substrate samples did not find any
limiting factors for site development, bathymetry values were the site selection study only
remaining analytical consideration for where to place the site.

Analysis of the bathymetric multi-beam data (Figure 10) identified a defined area of
depth in which to locate the proposed reef site. Additionally, depth values and contour lines
taken by the Survey Vessel closely matched NOAA LIDAR values as well as bottom machine
depths taken by the tonging boat in October. Multi-beam bathymetric analysis identified areas
both suitable and unsuitable to reef construction based upon depth: only depth values between
10.0 - 13.5 feet are considered suitable for reef construction in the area. Figure 11 shows
extracted multi-beam bathymetric data every 50 within the defined area. In Figure 12, the
suitable area relative to multi-beam depth data is denoted by the green hashed area. Figure 12
shows the primary results of suitability analysis related to bathymetric depth.

The proposed reef boundary box shown in Figure 12 was created based upon the
combined analysis of LIDAR, side scan, backscatter, multi-beam, and tonged substrate data and
analysis.

Recommended Action
-293
proposed location. Though the site selection report did not analyze the area for suitability
regarding finfish presence and/or oyster growth, the area is well known as a biologically diverse.
The absence of existing shell, seagrass, or other hard/live bottom in the area in combination with
substrate samples being relatively compact sand/mud mixtures identifies the area as suitable
bottom to enhance with reef material. Assumptions of reef construction and enhancement at the
proposed site are outlined in NCDMF Habitat and Enhancement SOPs and literature. Additional
water quality data from the area should be considered before permitting the site. A proposed site
construction map can be seen in Figure 13.

Figure 1: Proposed area to build new reef site AR-293. The area, locally known as
Point the southern opening of the Pamlico River.

Figure 2: NOAA LIDAR map used to locate a general area of interest.

Figure 3: Substrate sample locations gathered with patent tongs. Samples would later be
compared to the backscatter data obtained during the side scan survey to assign relative hardness
values.

Figure 4: , predominantly found in the southern end of the site in shallower than
10.5ft of water.

Figure 5: Sandy Mud, predominantly found in the northern end of the site in deeper than 10.5ft
of water.

Figure 6: Field data sheet and notes for substrate samples.

Figure 7: Sample locations with depths recorded by vessel bottom machine and substrate type
taken October 12, 2022 overlaid on multi-beam bathymetric scan recorded on January 4, 2023.
Further analysis compared bottom machine depths to NOAA LIDAR and NCDMF bathymetric
scans and were found to be reliable measurements.

Figure 8: Side Scan Imagery of AR-293 Site. No notable objects were found in the scan area or
the proposed reef area.

Figure 9: Backscatter showing relative hardness. Hardness values were compared to substrate
sample locations to ascertain site-wide substrate type. Proposed reef site is predominantly made
up of a mixture of sand and mud with no hard bottom, shell, or sea grass present.

Figure 10: Multi-beam bathymetric data showing depth in the area ranges from 3.6ft to 13.1ft
deep. Site selection for the reef requires a minimum depth of 10ft deep.

Figure 11: Extracted values at 50 increments of depth from multi-beam bathymetric scan. These
values were compared to both tong boat bottom machine depths and NOAA LIDAR depths.
Analysis concluded that depths taken in field are generally accurate +/-1 ft.

Figure 12: Multi-Beam bathymetric data selected by depth greater than or equal to 10.0ft deep
with substrate sample locations laid overtop as reference.

Figure 13: Proposed Reef Construction Map. 440
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