20000008 Ver 1_Monitoring Report_20071204

A LMG
LAND MANAGEMENT GROUP INC.
1?w Environmental Consultants
TO: Ms. Joanne Steenhuis
NC Division of Water Quality
127 Cardinal Drive Extension
Wilmington, NC 28405
RE: Mason Inlet Relocation Project- Biological Monitoring Report: December 2006 (Year 5)
Dear Joanne:
Enclosed is a copy of the December 2006 (Year 5) Annual Biological Monitoring Report for the Mason Inlet
Relocation Project. The report summarizes conditions of intertidal marsh, intertidal shoals, and intertidal
beachfront habitat as documented during December 2006 monitoring. It includes comparative analyses from
pre-project (Year 0) through December 2006 (Year 5). Copies of this document have been furnished to
reviewing state and federal regulatory agencies. Please contact our office if you need additional hard-copies
and/or digital copies.
Should you have any questions or comments regarding the findings of this report, please feel free to contact me
either by phone [phone]) or by email at bmanninq(a lmgroup.net.
Sincerely,
Land Management Group, Inc.
Brent Manning
Environmental Scientist
encl.
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O Mfg - WAi Fit UUALITY
Wp A aq AND TOPMWATHR BRANCH
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington,
NC 28402
LMG
LAND MANAGEMENT GROUP INC.
MW Environmental Consultants
TO: Ms. Joanne Steenhuis
NC Division of Water Quality
127 Cardinal Drive Extension
Wilmington, NC 28405
RE: Mason Inlet Relocation Project - Biological Monitoring Report: December 2006 (Year 5)
Dear Joanne:
Enclosed is a copy of the December 2006 (Year 5) Annual Biological Monitoring Report for the Mason Inlet
Relocation Project. The report summarizes conditions of intertidal marsh, intertidal shoals, and intertidal
beachfront habitat as documented during December 2006 monitoring. It includes comparative analyses from
pre-project (Year 0) through December 2006 (Year 5). Copies of this document have been furnished to
reviewing state and federal regulatory agencies. Please contact our office if you need additional hard-copies
and/or digital copies.
Should you have any questions or comments regarding the findings of this report, please feel free to contact me
either by phone [phone]) or by email at bmanning(aDlmgroup.net.
Sincerely,
Land Management Group, Inc.
Brent Manning
Environmental Scientist
encl.
i
I _C 4 2007

r
1)4 NR - WA T kR UUALl ry
VO AND.? Apo ST()t?PAY! ER BRANCH
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington,
NC 28402
MASON INLET RELOCATION PROJECT
BIOLOGICAL MONITORING REPORT.
DECEMBER 2006 (YEAR 5) MONITORING
Prepared for:
New Hanover County (NC), Permittee
Prepared by.
Land Management Group, Inc.
Environmental Consultants
Wilmington, NC
October 2007

1.0 INTRODUCTION
The goal of the biological monitoring program is to determine if there is a significant
difference between pre-construction (Year 0) and post-construction conditions (Year 1,
Year 2, Year 3, etc.) for specific parameters sampled annually in tidal marsh, intertidal
sand flat, and barrier island beachfront (i.e. intertidal surf zone) habitats located within
and adjacent to the project area. These data, in conjunction with data collected from
supplemental monitoring programs, will help to document any potential impact to
habitats resulting from project activities.
Pre- and post-construction monitoring provides data related to primary productivity,
benthic infaunal abundance and composition, substrate texture/organic content, and
macroinvertebrate densities (beachfront only). Quantitative and qualitative sampling
yields information to be used to determine if any deleterious effects may be attributable
to the inlet relocation project. The extent to which monitoring parameters will be
affected depends on various physical conditions (e.g. the character of the dredged
material, tidal and current regimes, etc.). Therefore, concurrent physical monitoring is
referenced in annual biological monitoring reports. In addition, unit area (acre or square
feet) of intertidal habitat type gain and/or loss is quantified and reported in annual
reports.
Concurrent monitoring conducted by LTNC-Wilmington provides more detailed
information related to waterbird utilization and water quality (pre- and post-construction).
Specifically, Dr. David Webster (tTNCW - Biological Sciences) oversees the waterbird
monitoring component. Additionally, Dr. Mike Mallin (UNCW- Center for Marine
Science) implemented a water quality monitoring program (2001 and 2002) that
evaluated conditions at five sampling stations located within Banks Channel, Mason
Creek, and the Atlantic Intracoastal Waterway (AIWW), respectively. Both monitoring
programs are directed independently of the biological monitoring detailed in this report.
Analysis of benthic infaunal communities is conducted by LINCW Center for Marine
Science each monitoring year and is usually included as an appendix to this document.
However, the Year 5 benthic summary report will be submitted as a separate document
once final data analyses are completed by UNCW. The hydrographic monitoring report,
and the waterbird monitoring report are submitted annually as independent documents to
reviewing regulatory agencies. The following report summarizes the methodology and
results for Year 5 post-construction monitoring.
2.0 METHODOLOGY
Annual biological monitoring is being conducted in three principal habitat types:
(1) Intertidal Marsh (adjacent to Mason Creek)
(2) Intertidal Sand Flat (back barrier island)
(3) Intertidal Surf Zone (barrier island beachfront).
Sampling for Year 1 post-construction conditions was conducted in December 2002
approximately seven (7) months after project completion. Annual monitoring will
continue for life of the permit or until such time deemed necessary by relevant federal
and/or state agencies. Data from post-construction monitoring events will be compared
to December 2001 pre-construction monitoring (Year 0) to identify any potential habitat
impacts resulting from project activities.
Sampling protocols for each habitat type are provided in the following text.
2.1 Intertidal Marsh (adjacent to Mason Creek):
2. 1.1 Monitoring Parameters
Selection of monitoring parameters has been based upon those factors potentially
impacted by project activities and those readily sampled and evaluated. The following
monitoring parameters have been identified:
2
(1) Spartina stem density
(2) Mature (>30 cm height) Spartina stem height
(3) Percent sand, silt, and clay of surface substrate
(4) Percent organic content of surface substrate
(4) Sedimentation rate
(5) Benthic infaunal abundance and species composition
(6) Distance (ft) loss or gain of intertidal marsh habitat at transect locations.
These parameters, while traditionally viewed as representative indicators of marsh habitat
structure and function, require less intensive and less frequent sampling than other biotic
or chemical indices.
At the time of sampling, presence or observable evidence of other faunal species utilizing
the area was noted.
2.1.2 Field Sampling Protocol
Sampling efforts focused on the area of potential impact where biota and physical
conditions (e.g. soil texture) are most likely affected by project activities and associated
perturbations such as altered flooding regime and sedimentation. Any perturbations to
tidal marsh will manifest in system responses distributed linearly from Mason Creek.
Therefore, three permanent 300-foot monitoring transects were established along a
roughly perpendicular axis on each side of Mason Creek (totaling six transects). These
transects are labeled MT1, MT2, MT3, MT4, MT5, and MT6, respectively). Five
permanent stations along each transect (located 5, 50, 100, 150 and 300 feet away from
the marsh edge along Mason Creek) were established prior to the initiation of the project.
The station located furthest from Mason Creek (300 ft) serves as the control plot for each
transect. Any stations affected by post-project erosion/sloughing near the creek bank
were re-established at prescribed distances from the new creek edge. Figure 1 depicts the
3
location of each monitoring transect established in the marsh and changes in the marsh
boundary along the creek from Year 0 to Year 5.
One-meter square quadrats at each station were sampled for stem density and height
range of S. alterniflora. Stem heights were grouped in categories based upon pre-
determined ranges (30-60 cm, 60-90 cm, 90-120 cm, >120 cm). Each height range was
assigned a value (1, 2, 3, and 4, respectively). The number of stem heights were
multiplied by the corresponding height value to obtain a height index. Cumulative height
indices for each quadrat were calculated and recorded.
Sediments were characterized according to percent sand/silt/clay and percent organic
matter (OM). One sample was collected at each of the fixed stations (5, 50, 100, and 150,
and 300-ft plots). Sediment samples were transferred to A&L Agricultural Labs
(Richmond, VA) for particle size analysis and OM by combustion.
Metal rebar installed flush with the sediment surface prior to project construction will be
used to evaluate sediment deposition and/or loss over time for each plot. Notched PVC
pipe will be used as a supplemental method of evaluating sediment accretion and/or loss.
Biological monitoring included a benthic infaunal survey. Three replicates of 15 cm-
deep cores (10 cm diameter) were sampled at three observation points (i.e. at 5', 150',
and 300' from creek edge) along three of the six transects (MT2, MT4, and MT6)
(N=27). Replicates were collected 10 ft from the pennanent vegetative quadrat at a
randomly-generated bearing. Individual core samples were transferred to sample bags
and labeled. All samples were transferred to UNCW-Center for Marine Science benthic
laboratory for processing and identification. Samples were fixed using a 10% formalin
solution and sieved through a 0.5 mm screen mesh to separate infauna from sediment and
vegetative material. Benthic infaunal organisms were enumerated and identified to the
lowest reliable taxonomic level. Species richness and abundance were calculated from
these data.
4
2.1.3 Data Analysis
Pre-construction mean values of each parameter were statistically compared using
Analysis of Variance (ANOVA)/paired t-tests for data normally distributed. Ninety-five
percent confidence intervals were used to determine statistically significant differences of
means (means are significantly different if confidence intervals do not overlap; p< 0.05).
Outliers (values +/- 2 times the standard deviation) were removed from all statistical
operations.
2.2 Intertidal Sand Flat:
Four permanent monitoring stations (S1, S2, S3, and S4) were established on each side of
the sedimentation basin at a distance >50 ft from the edge of the basin (refer to Figure 1).
Each of the monitoring parameters listed above were sampled at each station. Stem
density (if applicable); stein height (if applicable); percent sand/silt/clay and percent OM;
and benthic infauna were sampled and/or recorded at each station. At the time of
sampling, the presence or observable evidence of other faunal species was noted.
Three replicates of 15 cm-deep cores were sampled for benthic infauna at each of the four
stations. Benthic infaunal sampling at these stations was conducted using the protocol
outlined above.
Four supplemental monitoring stations (IV 1, IV2, IV3, and IV4) were established within
intertidal sand flat habitat near the new and former inlet locations during pre-project
monitoring (refer to Figure 1). Two of the four stations are permanent plots to be
sampled during each monitoring event. The other two stations, located near the former
inlet throat, were temporary (sampled once prior to project initiation) and have since been
converted to supratidal elevations in accordance with the project design. At each of the
5
two permanent supplemental stations, three replicates of 15 cm-deep cores were sampled
for benthic infauna.
Refer to Appendix A for photographs documenting site conditions at the time of the
December 2006 monitoring event.
2.3 Intertidal Surf Zone:
Numeric sampling of the mole crab (Emerita taploida) and coquina clam (Donax
variabilis) populations occurring between mean high water and mean low water was
conducted along twelve (12) transects (T1 through T12) located on Wrightsville Beach
and Figure Eight Island (refer to Figure 2). These transects encompass the Figure Eight
Island project nourishment area (approximately 10,000 If), 6000 if of beachfront north of
the project nourishment area, and an area of beachfront on Wrightsville Beach south of
the former inlet extending approximately 10,5001f south.
The locations of these transects reflect areas of beachfront nourished during different
time periods. Prior to project activities, the beachfront of the southern residential portion
of Figure Eight Island was last nourished in 1999-2000. The beachfront inclusive of T1
through T2 on Wrightsville Beach was nourished as part of the COE project in 2001-
2002. Areas of northern Wrightsville Beach (including T3 and T4) have not experienced
any beach nourishment. The beachfront inclusive of T6 through T10 was nourished in
March/April 2002 as part of the inlet relocation project. These transect were also
nourished in 2005 and 2006 as part of the Bank's Channel and Mason Creek dredging
project. The beachfront inclusive of T11 and T12 was nourished during the winter of
2000/2001 (one year before pre-project monitoring). T3 and T4 represent true control
transects since these areas had not experienced any recent beach nourishment prior to
monitoring.
Four replicates were sampled at three locations (low, mid, and high) of the swash zone
6
along each transect during the monitoring event. Therefore, at total of twelve samples
were collected at each transect. A 15 em-deep core (10 cm in diameter) was used to
sample mole crabs and coquina clams. Each core was sieved at the time of sampling
using a 3-4mm mesh box sieve. All individuals were enumerated and recorded.
Data collected from transects within the nourishment area are compared to control
transects (and other transects not affected by nourishment during the 2001/2002 season)
to evaluate the extent of population regeneration. Control transects (T3 and T4) are
located in areas that have not experienced beach nourishment within the last five years.
However, two of the transects on Wrightsville Beach (T1-T2) were likely impacted
during the beach nourishment that was conducted in early 2006 prior to Year 5
monitoring.
3.0 RESULTS
3.1 Intertidal Marsh
Stem Density
Post-Construction (Year 5)
Mean Spartina stem density for all quadrats sampled was 31.4 stems/m2 (N=29). There
was no significant difference observed between mean stem density on the north and south
sides of Mason Creek. Mean stem densities of quadrats located on the north and south
sides of Mason Creek were 30.0 +/- 10.4 stems/ m2 and 29.9 +/- 22.1 stems/ in
respectively (refer to Figure 3). There was no observed significant difference in stem
density related to distance from creek (refer to Figure 4). Of the six transects sampled,
stem densities were greatest in Transect 4 (mean stem density of 47.0) (refer to Figure 5).
7
Pre-Construction (Year 0) vs. Post-Construction (Year I through 5)
A significant decline in stem density was measured between Year 5 and Year 4 (Year 4 =
59.5 +/- 33.3; Year 5 = 30.0 +/- 16.8). Year 5 mean density is also significantly different
than the mean density observed in Year 0 (63.3 +/- 22.4 stems/m2) (refer to Figure 6).
Stem Height
Post-Construction (Year 5)
Height indices were significantly higher on the north side of Mason Creek than those
indices calculated for plants on the south side of the creek (refer to Figure 7). There was
no significant difference in height indices as a function of distance from creek bank (refer
to Figure 8). Of the six transects sampled, stem heights were greatest in Transect 3
(mean height index of 84.8) (refer to Figure 9).
Pre-Construction (Year 0) vs. Post-Construction (Year 1 through Year 5)
Year 5 stem height indices show significant decrease from previous post construction
monitoring events (Year 1 through Year 4). A dramatic decrease was observed between
Year 4 (106.9) and Year 5 (57.4) post-construction monitoring events. In addition, height
indices for all stations were significantly different between pre-construction (Year 0,
93.6) and post-construction (Year 5, 57.4) (refer to Figure 10).
Sediments
Relative deposition or loss of material from the marsh surface was measured from
notched PVC installed prior to project construction in December 2001. Table 1 provides
sediment loss/gain (cm) measured during Year 5 monitoring for each quadrat location in
the marsh. Dramatic changes in channel location have necessitated the installation of
new markers at the 5', 50', and 100' interval limiting the scope of the sediment
8
deposition data.
Sediments collected from the south side of Mason Creek exhibited significantly higher
percent sand than sediments collected from the north side of Mason Creek (90.8 +/- 4.1%
sand and 77.9 +/- 7.2% sand, respectively) (refer to Figure 11). There was no significant
difference in percent sand as a function of distance from the creek bank (refer to Figure
12). However, samples collected 300 ft from Mason Creek consistently exhibited the
highest percent sand (87.0 +/- 11.5% sand).
Table 1. Sediment Loss/Gain in Marsh Stations ( A Year 0 to Year 5)

Quadrat Position Material Loss or Gain

(cm)'
Quadrat Position Material Loss or Gain

(cm)
MT 1-5 0.0 MT4-5 0.0
MT 1-50 0.0 MT4-50 0.0
MT 1-100 8.0 MT4-100 0.0
MT1-150 4.0 MT4-150 0.0
MT 1-300 3.0 MT4-300 -1.0
MT2-5 0.0 MT5-5 5.0
MT2-50 6.0 MT5-50 0.0
MT2-100 15.0 MT5-100 12.0
MT2-150 0.0 MT5-150 2.5
MT2-300 0.0 MT5-300 3.0
MT3-5 0.0 MT6-5 0.0
MT3-50 0.0 MT6-50 3.25
MT3-100 0.0 MT6-100 0.0
MT3-150 0.0 MT6-150 1.75
MT3-300 0.0 MT6-300 3.0
No measurement of sediment loss/gain available for stations reestablished during 2002 monitoring.
9
Sediments collected from the north side of Mason Creek exhibited significantly higher
percent organic matter than sediments collected from the south side of Mason Creek
(3.8+/- 2.1% OM and 0.8 +/- 0.6% OM, respectively) (refer to Figure 13). There was no
significant difference in percent OM as a function of distance from the creek bank (refer
to Figure 14). However, samples collected 150-ft. from Mason Creek consistently
exhibited slightly higher percent OM (2.9 +/- 2.4% OM).
Pre-Construction (Year 0) vs. Post-Construction (Year 1 through 5):
There was no statistical difference observed between mean percent sand for pre-
construction (December 2001, 88.5%) and post-construction Year 1 through 5 samples
(84.0%, 84.3%, 87.6%, 87.7, 86.7 respectively) (refer to Figure 15). Similarly, there was
no statistical difference observed between mean percent OM for pre-construction
(December 2001, 2.0%) and post-construction Year 1 through 5 samples (3.7%, 3.5%,
3.1%, 1.9%, and 1.9% respectively) (refer to Figure 16).
Benthic Infauna
Benthic infaunal identification and data analysis was conducted by Dr. Martin Posey and
Troy Alphin of UNCW - Center for Marine Science. Their summary (including results
and discussion) will be provided at a later date as a separate document.
3.2 Intertidal Sand Flat
Sediment Comtuosition
Mean percent sand of samples collected from the intertidal sand flats (S and IV series)
was 95.7 +/- 0.8%. Percent sand values ranged from 94.0% (S 1) to 97.0% (IV2).
Mean percent OM of samples collected from these intertidal sand flats was 0.23 +/-
10
0.28%. Percent OM values ranged from 0.1% (IV2) to 0.8% (S2).
Pre-Construction (Year 0) vs. Post-Construction (Year I through 5):
There was no statistical difference observed in mean percent sand values between Year 0
and Year 5. Though sediments exhibited higher percent OM values in Year 1, this
increase was not statistically significant from Year 0 or Year 5 percent OM values.
Conversely, samples collected during post-construction (Year 1 through 5) monitoring
contained less percent sand than those samples collected during pre-project monitoring -
though this difference was not statistically significant.
Benthic Infauna
Benthic infaunal identification and data analysis was conducted by Dr. Martin Posey and
Troy Alphin of UNCW - Center for Marine Science. Their summary (including results
and discussion) will be provided at a later date.
3.3 Intertidal Surf Zone
A total of 20 coquina clams and 2 mole crabs were collected along twelve transects of the
intertidal surf zone during the December 2006 (Year 5) sampling event. For coquina
clams, the `low' surf zone exhibited the greatest number of individuals (9). The greatest
number of coquina clams were observed along Transect 7 (with 7 clams).
Refer to Figures 17 through 18 for a graphical depiction of macroinvertebrate abundance
and distribution during Year 5 sampling.
Pre-Construction (Year 0) vs. Post-Construction (Year I through 5):
Less coquina clams were observed along sampling transects in Year 5 than in Year 0 (45
and 20, respectively) (Figure 19). Six (6) of the twelve (12) transects exhibited lower
numbers of coquina clams in Year 5 than in Year 0. Three (3) transects exhibited a
increase in the number of coquina clams from Year 4 to Year 5 (Figure 20). Year 5
sampling yielded similar totals to Year 4, the lowest of the monitoring period. More
coquina clams were observed in the low intertidal zones in Year 5 than in Year 0. The
number of coquina clams observed in the high intertidal zone has decreased in
subsequent years following pre-construction monitoring (Figure 21).
4.0 DISCUSSION:
4.1 Vegetation (Spartina alterniflora)
The mean stem density of Spartina alterniflora decreased from Year 4 (2005) monitoring
but was slightly higher than that of Year 3 (2004). Year 5 mean density was also
significantly lower than Year 0 pre-construction conditions (61.4 and 30.0, respectively).
Stem density decreased by 29.5% from Year 4 to Year 5. These trends were also seen at
the 300' sampling locations (i.e. control sites) as densities decreased 41.5% from Year 4
to Year 5 and 35.5% from Year 0 to Year 5 (Figure 22). Differences observed across
control sites suggest that non-project related conditions (including inter-year variation)
contribute to the observed differences in stem densities.
In general, no significant differences in Spartina stem densities were observed between
transect position (north vs. south) nor quadrat location (5', 50', 150', and 300').
Increased sediment deposition along MT 6 resulted in significant decline and/or loss of
new Spartina growth in this location (likely resulting from its proximity to the flood tide
shoal). Additional tidal energy through Mason Creek has resulted in bank undercutting
along the southern edge of the marsh near MT 5 and MT 4.
12
Stem height indices were significantly greater on the north side of Mason Creek than on
the south side in Year 5. While Year 0 data did not yield a statistical difference in stem
height indices between the north and south sides of the creek, it has been noted that the
north side of the creek is a more mature marsh system with generally taller Spartina
stems. While stem height indices were highest during Year 4 monitoring (greater than
stem heights observed during pre-construction conditions), height indices have
significantly declined during Year 5. Decline in stem heights has also been observed in
control quadrats as well (Figure 23). Observed differences within control sites are
suggestive of other factors (such as inter-year variation) contributing to observed
differences in stem heights. In addition, increased sediment deposition near MT 5 and
MT 6 may have contributed to reduced stein densities and stem heights.
4.2 Sediments
Sediments collected from the south side of Mason Creek exhibited significantly higher
percent sand than sediments collected from the north side of Mason Creek. Conversely,
sediments from the north side of Mason Creek exhibited significantly higher percent OM.
This same pattern was observed during the pre-project monitoring conducted in
December 2001. As stated in the Pre-Construction Biological Monitoring Report,
sediment data suggest that the south side of Mason Creek is a relatively new, accreting
marsh system compared to the marsh located north of the creek.
As was reported in Year 0, there was no significant difference in percent sand as a
function of distance from the creek bank. However, samples collected near the edge of
Mason Creek consistently exhibited the highest percent sand. Likewise, there was no
significant difference in percent OM as a function of distance from the creek bank.
However, samples collected near the edge of Mason Creek exhibited the lowest percent
13
OM. During Year 1 and Year 2 percent OM was highest at stations furthest from Mason
Creek (i.e. 300-ft). Results from Year 5 closely resemble those from pre-construction
monitoring (Year 0).
As documented in Year 0, mean percent sand of samples collected from the intertidal
sand flats located near the inlet was higher than samples collected from the marsh.
Likewise the percent OM of samples collected from the intertidal shoals was significantly
less than the percent OM of samples collected from the marsh. In general, intertidal
shoals consist of courser material associated with high-energy environments. The marsh
dissipates energy and allows for the deposition of finer material and the accumulation of
organics.
4.3 Benthic Invertebrates (Backbarrier Infauna)
Physical (i.e. hydrographic) monitoring is conducted on a quarterly basis to document
sedimentation processes in the inlet area over time. Approximately 87 acres (ac) of
subtidal, intertidal, and supratidal habitat is surveyed to detennine shifts in habitat types
throughout the area. According to the April 2007 survey data from Gahagan & Bryant
Associates, Inc. (GBA), 71.0% (62.1 ac) of the surveyed area consists of intertidal
habitat. This represents an increase of 3.6 ac since the October 2002 report. Overall, a
net gain of intertidal habitat from pre-project conditions to the October 2006 survey has
been 7.4 ac. Over the same monitoring period, supratidal area has increased 15.5 ac, and
subtidal area has decreased 23.6 ac. Please refer to the quarterly hydrographic reports
submitted under separate cover by GBA for more detailed information regarding
bathymetric conditions within and adjacent to the relocated inlet.
4.4 Benthic Invertebrates (Beachfront)
Abundances of benthic macroinvertebrate species of the beachfront were similar to those
observed during Year 4 monitoring. In general, relative abundances of coquina clams
14
and mole crabs remain low due to the time period of sampling. Of the 144 cores
sampled, 20 coquina clams and 2 mole crabs were observed. The highest numbers of
coquina clams and mole crabs were observed during Year 3 post-construction (45
coquina clams and 37 mole crabs). Given the time of sampling and associated limited
data set, it is difficult to evaluate real trends in macro-invertebrate populations along the
beachfront.
Erosion and beachfront nourishment activities contribute to temporal decreases in these
populations. Periodic maintenance projects along the beachfront of Figure 8 Island and
the northern end of Wrightsville Beach may result in burial of benthic organisms.
Studies have indicated that larger, more mobile species burrow through new sand or
avoid disturbance through migration. In general, beachfront disposal results in short-terns
declines in species abundance, biomass, and taxa richness. However, most studies have
indicated that assemblages recover within 2 to 7 months of project completion provided
that the disposal material is beach suitable (i.e. greater than 90% sand) (Hackney et al.
1996, Nelson 1993, USACE 2001).
5.0 CONCLUSION:
Pre-construction monitoring data demonstrate some observed patterns related to station
location (i.e. distance and position relative to creek). Year 5 monitoring demonstrated
declines in both stem density and height from Year 4. Both stem density and stem height
indices are consistent with those metrics observed in Year 3 post-construction
monitoring. Year 5 stem densities and height indices are significantly lower than Year 0
(pre-construction). However, these differences are observed in the 300-ft control
quadrats - suggesting that other factors (including inter-year variation) may be
contributing to observed differences. In addition, increased sediment deposition (at MT
6) and erosion along the southern edge of Mason Creek (near MT 4 and MT 5) appear to
affect the growth and survivorship of Spartina stems.
15
As has been documented in previous monitoring reports, macroinvertebrate data collected
from the beachfront are relatively sparse. The early winter period of sampling
contributes to the limited data set. That being said, the numbers of coquina clams and
mole crabs sampled in Year 5 are consistent with those observed in Year 4. These results
show a decline from Year 3. Recent nourishment activities completed in April 2006 may
have affected spring recruitment along portions of the beachfront sampled - contributing
to relatively low numbers of coquina clams and mole crabs observed. Given the scope
and timing of sampling, trends in macroinvertebrate populations are difficult to identify.
Though temporal declines in populations may occur shortly after nourishment activities,
inter-year variation and other co-variates may contribute to population responses.
16
FIGURES
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Figure. 5 Analysis of Stem Density vs. Transect Number (Year 5)
1
N
E
^L,
W
Q
(n
E
W
4--
0
N
tf
W
E
a)
4-
C/)
Figure. 6 Analysis of Stem Density by Year (Pre-Project vs. Post-Project)
N
E
^L
W
Q
V)
E
N
Cn
4-
O
tf
Cn
1_
N
E
N
CO
30
30
70
30
50

30

10-
N 175
0 p = <0.0001
10
0 1 2 3 4 5
Year
1 2 3 4 5 6
Transect Number
Figure. 7 Analysis of Height Index vs. Position Relative to Mason Creek (Year 5)
1
O
_:3
E 1
4-
O
X
O
C
L
O)
Z
2
E
O
50-
00-
50-
N = 28
0 P=0.0011
--
North South
Position Relative to Mason Creek
Figure. 8 Analysis of Stem Height Index vs. Distance from Mason Creek (Year 5)
150
N=30
p = 0.5695
E
- _
100 -
O T -
- 1}
it
X
O
-- - - --
C
50
E
N
U) 0
5 50 100 150 300
Distance from Mason Creek (ft)
Figure. 9 Analysis of Height Index vs. Transect Number (Year 5)
_C
(>3
E
N
CO
1
4-
O
X
N
C
s
E
N
50
N=30
p = <0.0001 1
0 -
1 2 3 4 5 6
Transect Number
Figure. 10 Analysis of Height Index by Year (Pre-Project vs. Post-Project)
200-
=3
CO -
E 150
4-
O
*k
X 100
O
C
.C -
50 -
._ r
O N=176
}' 0
p = <0.0001
0 1 2 3 4 5
Year
Figure. 11 Analysis of % Sand of Sediments vs. Position Relative to Mason Creek
C
CU
07
c
a?
U
L
LL
uu
90
80
70
60
N=30
50 p = <0.0001
North South
Position Relative to Mason Creek
Figure. 12 Analysis of % Sand of Sediments vs. Distance from Mason Creek
C
cv
cn
c
U
U
L
Q?
0-
00-
90-
80-
70-
60-
=_
N 30
50- p = 0.4064
5 50 100 150 300
Distance from Creek (ft)
Figure. 13 Analysis of % Organic Matter of Sediments vs. Position Relative to Mason Cree
1°
L -
(D
.«r
ca
_U
C
M
2)
O
C
(D
U
L
/?a)
LL
N=30
p = <0.0001
3
r
3
? r
North South
Position Relative to Mason Creek
Figure. 14 Analysis of % Organic Matter of Sediments vs. Distance from Mason Creek
L
Q?
U_
.C
M
2'
O
C
Q?
U
L
a
N=30
e p = 0.6292
8-
7-
5-
3-
2-
5 1
50 100 150 300
Distance from Creek (ft)
Figure. 15 Analysis of % Sand by Year (Pre-Project vs. Post-Project)
C
m
Co
C
a?
U
L
LL
0 1 2 3 4 5
Year
Figure. 16 Analysis of % Organic Matter by Year (Pre-Project vs. Post-Project)
A
L
Q?
c?
G
U
co
0)
O
c
a?
U
L
a?
d
0
N = 206
g p = .0659
8-
7-
6-
-
5-
4
2
1
01
0 t 2 3 4_ 5
Year
Figure. 17 Total Number of Coquina Clams and Mole Crabs by Surf Zone
10-
8-
U)
7-:
j 6-i
5-
4-
O
4-
3
O 'I
~ I
2
1
O
i
1
.Coquina Clams
Mole Crabs
Low Mid High
Transect Position
Figure. 18 Total Number of Coquina Clams and Mole Crabs by Transect Number
8-
7-
N
C6 6-
5 C -
-i
..p
C
`+-
p 4-
3-
12
2 -'
1-
0
.Coquina Clams
j Mole Crabs
1 2 3 4 5 6 7 8 9 10 11 12
Transect Number
Figure. 19 Total Number of Coquina Clams and Mole Crabs
by Year (Pre-Project vs. Post-Project)
C
4--
O
H
UV
45 45

40

(37) 37
35 (35)

30 (30)

25

20 (20)
(18)
15

10 (to)

5

0
®Coquina Clams
M Mole Crabs
0 1 2 3 4 5
Year
Figure. 20 Total Number of Individuals by Transect Number and Year
30-
25
N
20-'j
>
"O
C
O
10
1
5-'
O -;
1 2 3 4
5 6 7 8 9
Year by Transect Position
10 11 12
¦ Year o
Year 1
Year 2
¦ Year 3
Year 4
¦ Year 5
Figure. 21 Total Number of Individuals by Transect Position and Year
35
30 -?
25-2
C l
f
45 20 -
co
15
I
10-
i
5 -
O -':
O 1 2 3 4 5 O 1 2 3 4 5 O 1 2 3 4 5
Low Mid High
¦ Year 0
Year 1
¦ Year 2
® Year 3
Year 4
. Year 5
Intertidal Surf Zone
Figure. 22. Stem Densities at Control Locations (300' away from marsh edge) by Year
1
00
N=36
so p = <0.0001
80-
70-
60-
40-
30-
20-
- -
10
0 1 2 3 4 5
Year
Figure. 23. Stem Heights at Control Locations (300' away from marsh edge) by Year
200
a?
ca
E
a)
4-
0
X ,
(1)
c
4-4
s
2
E
a?
W
0-i
0 1 2 3 4 5
Year
APPENDIX A.
SITE PHOTOGRAPHS DEPICTING
DECEMBER 2006 (YEAR 5) CONDITIONS
18
(2) View of S4 sampling location on south side of creek

Mason Inlet
Relocation Project
New Hanover County, NC
LMG
D 11ANAQU,1ENI OROLT ,.
Site Photographs
December 2006
(Post-Construction Year 5)
(3) Quadrat sampling (stem height and density) on north side of Mason Creek
Mason Inlet
Relocation Project
New Hanover County, NC
9 Y ?'
xr
1 y
nt
4 LMG
LAND nth NAGEMEN'1 I,ROVI
,q'- . ,
Site Photographs
December 2006
(Post-Construction Year 5)
(4) Station (S1) located north of sedimentation basin (facing east)
(6) Transect MT5 located on the South side of Mason Creek
Mason Inlet
Relocation Project
New Hanover County, NC
LMG
I.A Kr `1ANW'Al N7 ..F 0"1
Site Photographs
December 2006
(Post-Construction Year 5)
(7) Shoreline along North side of Mason Creek
Mason Inlet
Relocation Project
New Hanover County, NC
LMT
Site Photographs
December 2006
(Post-Construction Year 5)
(8) Sediment deposition at MT6 located on the South side of Mason Creek
(9) Foraging activities along Northern portion of Mason Creek

Mason Inlet
Relocation Project
New Hanover County, NC
LMG
K c' lI'J'( ?,kGk.!F
Site Photographs
December 2006
(Post-Construction Year 5)