20041216 Ver 1_Year 8 Monitoring Report_20100813

tLMG
'?Aw' LAND MANAGEMENT GROUP ixc.
Environmental Consultants
August 9, 2010
TO: Mr. John Dorney
NC Division of Water Quality
1617 Mail Service Center
Raleigh, NC 27699

AUG IR&EM91
1 3 2010
DENR • WATER OVAIITy
WET! UD$ AND STORMWATER ORANCM
RE: Mason Inlet Relocation Project - Biological Monitoring Report: December 2009 (Year 8)
Dear John:
Enclosed is a copy of the December 2009 (Year 8) 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 2009 monitoring. It includes comparative analyses from
pre-project (Year 0) through December 2009 (Year 8). Copies of this document have been furnished to the NC
Division of Water Quality (DWQ). Note that the enclosed document includes the benthic summary report
recently received from UNC-Wilmington.
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 Christian Preziosi either
by phone [phone]) or by email at cpreziosi aOlmgroup.net.
Sincerely,
Land Management Group, Inc.
Jenny Johnson
Environmental Scientist
encl.
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
NEW HANOVER COUNTY, NC
BIOLOGICAL MONITORING REPORT:
YEAR 8 (2009) POST-CONTRUCTION MONITORING
• A UG 13 ?QtO
Prepared for ftRA .4WA
New Hanover County (NC), Permittee
Prepared by:
Land Management Group, Inc.
Environmental Consultants
Wilmington, NC
•
August 2010
0

TABLE OF CONTENTS
1. INTRODUCTION ..............................................................................................................1
II. METHODOLOGY ............................................................................................................2
A. MONITORING PARAMETERS ..................................................................................2
B. FIELD SAMPLING PROTOCOL ................................................................................3
C. DATA ANALYSIS .......................................................................................................5
III. RESULTS ...........................................................................................................................5
A. STEM DENSITY ..........................................................................................................5
B. STEM HEIGHT ............................................................................................................6
C. SEDIMENTS ................................................................................................................6
D. BENTHIC INFAUNA ..................................................................................................7
IV. DISCUSSION ....................................................................................................................8
A. VEGETATION (Spartina alterniflora) ........................................................................8
B. SEDIMENTS ..............................................................................................................10
C. BENTHIC INVERTEBRATES (BACKBARRIER INFAUNA) ...............................10
D. PHYSICAL MONITORING AND HABITAT TYPES .............................................10
V. CONCLUSION ................................................................................................................11
List of Tables, Figures and Appendices
Figure 1 ..........................................................................................Original Transect Location Map
Figure 2 .........................................................................................Updated Transect Location Map
Figure 3-18 ................................................................................................................. Data Analysis
Appendix A. Benthic Infaunal Summary of Findings
Appendix B. September 2009 Site Photographs
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MASON INLET RELOCATION PROJECT
ANNUAL BIOLOGICAL MONITORING REPORT (YEAR 8)
1. 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,
0 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.
•
Additional monitoring is conducted by UNC Wilmington and Audubon North Carolina.
At the onset of the project, the Mason Inlet Waterbird Management Plan was developed
to help protect critical nesting habitat along the north end of Wrightsville Beach.
Audubon North Carolina manages currently manages this area through the installation of
informational signage, patrols, and visitor education programs. In addition, Audubon
assists UNC-Wilmington with monitoring of bird usage and nest success. Analysis of the
benthic infaunal communities is conducted by UNCW Center for Marine Science each
monitoring year. The summary of findings for the benthic analysis is included as an
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appendix to this document (refer to Appendix A). The hydrographic monitoring report
and the waterbird monitoring report are submitted annually as independent documents to
reviewing regulatory agencies.
Reports for post-construction monitoring Year 1 to Year 6 were based on data collected
during the late fall/early winter season. The timing of the sampling during these years
was intended to coincide with the original pre-construction monitoring event conducted
in early December 2001. During an interagency meeting in April 2008, the U.S. Army
0 Corps of Engineers (USACE) requested that biological monitoring be shifted to the
growing season. In addition, the USACE modified the monitoring plan to discontinue
macro-invertebrate sampling of the beachfront and benthic infaunal sampling of intertidal
flats. As a result of the meeting, Year 7 monitoring was conducted in August 2008
(approximately ten months after the Year 6 event). Year 8 monitoring was conducted in
September 2009. All future monitoring will occur during the late summer/early fall
season. Subsequent analysis of inter-year trends in data (winter sampling in Year 0
through Year 6 and summer sampling in Years 7 and 8) must take into consideration
variability due to seasonality. The following report summarizes the methodology and
results for Year 8 (September 2009) post-construction monitoring.
II. METHODOLOGY
• Sampling for Year 1 post-construction conditions was conducted in December 2002
approximately seven (7) months after project completion. Annual monitoring is to
continue for the life of the permit or until such time deemed necessary by relevant federal
and/or state agencies. Note that based upon the April 2008 interagency meeting,
sampling of macro-invertebrates of the beachfront and benthic infauna of intertidal flats
has been discontinued. Six years of post-construction data for these biological indices
has been provided in earlier reports.
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A. 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 are included in the assessment:
(1) Spartina stem density
(2) Mature (>30 cm height) Spartina stem height
(3) Percent sand, silt, and clay of surface substrate
0 (4) Percent organic content of surface substrate
(5) 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. In addition to the identified quantitative sampling, qualitative
observations of marsh and/or intertidal habitat may be noted. Photographic
documentation of Year 8 sampling is provided in Appendix B.
B. 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.
0 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 MT I, 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-
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established at prescribed distances from the new creek edge. In these cases where only
one or two stations within a transect were required to be re-established, the new station
was offset perpendicular to the original transect. However, due to the level of erosion
observed along the southern section of the marsh, all stations in transects MT4-MT6 were
re-established in 2008. These stations were re-established in areas containing stable low
marsh habitat and transition into areas of slightly higher topography. Figure 1 depicts the
location of each monitoring transect established in the marsh and changes in the marsh
boundary along the creek from Year 0 to Year 7. Figure 2 provides additional
0 information on the re-established transect locations and updated aerial photography.
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 stems in each category was
then 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.
0 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.
Note that the loss of stations throughout post-construction monitoring has limited the
scope of this assessment.
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)
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(N=27). Replicates were collected within 10 ft of the permanent 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.
•
C. Data Analysis
Mean values of each parameter were statistically compared using Analysis of Variance
(ANOVA)/paired t-tests. 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.
III. RESULTS
A. Stem Density
(1) Post-Construction (Year 8)
Mean Spartina stem density for all quadrats sampled was 40.9 +/- 8.4 stems/m2 (N=30).
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 41.1+/- 7.1 stems/ m2 and 40.7 +/- 9.7 stems/ m2,
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 5 (mean stem density of 47.8 stems/m2) (refer to
Figure 5).
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(2) Pre-Construction (Year 0) vs. Post-Construction (Year 1 through Year 8)
Mean stem density of Year 8 (40.9 stems/m2) was not significantly different from Year 1, Year
2, and Year 5. However, stem densities were significantly lower than in Year 0 (pre-
construction) and Year 4 (post-construction) (refer to Figure 6). Mean stem density in Year 8
was significantly higher than in Year 3, Year 6, and Year 7.
S. Stem Height
•
(1) Post-Construction (Year 8)
There was no significant difference observed between height index on the north and
south sides of Mason 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 2 (mean height index of 135.0)
(refer to Figure 9).
(2) Pre-Construction (Year 0) vs. Post-Construction (Year 1 through Year 8)
The observed mean stem height index for Year 8 was 104.5 +/- 30.4. Observed stem
heights during Year 8 were not significantly different than those observed during Year 0
(pre-construction) and Year 4 (post-construction) (refer to Figure 10). Stem heights were
significantly higher in Year 8 than in Year 1, Year 2, Year 3, Year 5, Year 6, and Year 7.
Of the nine years of monitoring (including pre-construction), the mean stem height index
0 was greatest during Year 4 and Year 8 (post-construction).
C. Sediments
(1) Post-Construction (Year 8)
Relative deposition or loss of material from the marsh surface was measured from
notched PVC installed prior to project construction in December 2001. As previously
noted, changes in channel location have necessitated the installation of new markers at all
stations within the MT4, MT5, and MT6 transects in 2008, thereby limiting the scope of
40 6
0
the sediment 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 (87.0 +/- 4.5%
sand and 75.0 +/- 13.1 % 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 5 ft from Mason Creek consistently exhibited
the highest percent sand (88.0 +/- 4.9% sand).

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 (6.0
+/- 4.4% OM and 2.0 +/- 0.9% 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 5 ft. from Mason Creek consistently exhibited
slightly lower percent OM (1.5 +/- 0.8% OM).
(2) Pre-Construction (Year 0) vs. Post-Construction (Year 1 through Year 8)
There was no statistically significant difference observed between mean percent sand for
pre-construction (December 2001, 84.5%) and post-construction Year 1 through 8
samples (80.0%, 81.1%, 86.2%, 86.1%, 84.8%, 84.1%, 84.6%, and 83.9% respectively)
(refer to Figure 15). Similarly, there was no statistical difference observed between mean
percent OM for pre-construction (December 2001, 2.8%) and post-construction Year 1
0 through 8 samples (4.2%, 4.0%, 2.9%, 2.6%, 2.2%, 2.2%, 3.2%, and 3.4% respectively)
(refer to Figure 16).
D. Benthic Infauna
Benthic infaunal identification and data analysis was conducted by Troy Alphin,
Research Associate at the Center for Marine Science (University of North Carolina at
Wilmington). A summary report of findings with supporting tables and figures is
included as Appendix A.
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a
IV. DISCUSSION
A. Vegetation (Spartina alterniflora)
As identified above, Year 8 annual monitoring was conducted in September 2009. Year
7 annual monitoring was conducted in August 2008. During prior years (Year 0 through
Year 6), monitoring was conducted during late November or early December of each
year. As a result of the temporal shift, seasonality is introduced as a confounding
variable when evaluating inter-year (i.e. Year 7 and Year 8 vs. Year 0 through Year 6)
data trends. Inter-year patterns inferred through data collected in future monitoring
events will not be influenced by seasonality since future monitoring is to occur during
August or early September of each year.
Comparison between years is possible while recognizing seasonality as a confounding
variable. It should be noted that the mean stem density of Spartina alterniflora during
Year 8 monitoring was significantly higher than Year 7. However, overall stem densities
for Year 8 remain significantly lower than those documented during pre-construction
monitoring. Of all the monitoring events (including pre-project), Year 4 exhibited the
greatest mean stem density. These same trends are evident in the control plots (Figure
17). In consideration of this, inter-year variation (rather than project-related factors)
appears to have a greater influence on observed 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').
Sedimentation processes of the inlet throat and flood tide shoals have resulted in
adjustments to the channel pattern of Mason Creek and associated sediment losses and/or
gains along the length of the creek. As a result, transects MT4, MT5, and MT6 (on the
southern side of the creek) were re-established in 2008 (Year 7). Channel banks along
MT4 and MT5 exhibited some erosion (3 ft and 11 ft, respectively) as evidenced by the
sampling station distance from the creek bank. Accretion along the creek edge at transect
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MT6 is providing some intertidal habitat for volunteer Spartina. However, it appears that
the dynamic environment at this location (field observations documented recent sediment
deposition at transect MT6) is largely prohibitive to robust growth of Spartina stands.
This is evident by the low stem densities observed at this transect relative to other
transect during the Year 8 monitoring.
Stem height indices were not significantly different on the north side of Mason Creek
than on the south side in Year 8. However, stem height on the north side appeared to be
0 higher than on the south side. 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. For all years of monitoring (including pre-construction), stem height indices were
highest during Year 4 and Year 8 monitoring. However, a decline was observed in Year
5 through Year 6. This decline was also observed in the control sites until the re-
alignment of transects MT4, MT5, and MT6 prior to the Year 7 monitoring event (Figure
18). In light of the results for all years and the observed pattern for control sites, it
appears as though inter-year variation has a more prominent effect on stem heights than
project-related factors.
B. 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
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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
OM. During Year 1 and Year 2 percent OM was highest at stations furthest from Mason
Creek (i.e. 300-ft). Results from Year 8 closely resemble those from pre-construction
monitoring (Year 0).
C. Benthic Invertebrates (Backbarrier Infauna)
•
A summary of findings for the benthic infaunal sampling and characterization is provided
as Appendix A of this report. Overall, mean abundances were highly variable in 2009.
Species richness was similar to previous years with no site differences. Diversity was
relatively low as in previous years. Please refer to Appendix A for more detailed
characterization of the benthic community sampled during Year 8.
D. Physical Monitoring and Habitat Types
Physical (i.e. hydrographic) monitoring is conducted on an annual basis to document
sedimentation processes in the inlet area over time. As part of this monitoring effort,
Gahagan & Bryant Associates, Inc. (GBA) produces annual monitoring reports that
include detailed shoreline/channel profiles and bathymetric maps. Based upon the data
collected, observed trends in sediment deposition and loss are evaluated. As evidenced
through physical survey and aerial imagery, adjustments occurring within the inlet
0 interior include increased shoaling of the flood-tidal delta and slight adjustments of the
channel thalweg connecting Mason Creek to the inlet throat. Intertidal sand flats and
volunteer marsh continues to accrete behind Wrightsville Beach via increased sand
deposition in these areas. Please refer to the hydrographic reports submitted under
separate cover by GBA for more detailed information regarding bathymetric conditions
within and adjacent to the relocated inlet.
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V. CONCLUSION
Pre-construction monitoring data demonstrate some observed patterns related to station
location (i.e. distance and position relative to creek). Year 8 monitoring demonstrated a
significant increase in both stem height and density relative to Year 7. Stem density
remains significantly lower than Year 0 (pre-construction) and lower than Year 4 (post-
construction). However, stem height in Year 8 was not significantly different from Year
0 0 or Year 4. Given the range of recorded data and temporal variation in sampling it
appears that inter-annual variation may play a strong role in determining plant growth,
rather than project-related interference. In addition, observed stem densities and stem
heights during Year 4 were not significantly different from pre-construction data. This is
also indicative of the role of inter-year variation relative to project-related trends.
During Year 6 and Year 7 monitoring, it appeared as though growth and survivorship of
Spartina stems were affected by increased sediment deposition (at MT6) and erosion
along the southern edge of Mason Creek (near MT4 and MT5). However, both stem
densities and stem heights were significantly higher in Year 8 than in Year 6 and Year 7.
MT6 continued to exhibit low stem density and height index in conjunction with
accretion from sediment deposition patterns.
Inlet and channel morphology demonstrate patterns of shoaling with the inlet interior
• (particularly the flood shoal complex). Channel adjustments of Mason Creek (sediment
loss or gain) necessitated the reestablishment of three transects (MT4, MT5, and MT6)
prior to Year 7 sampling in 2008. In addition, sampling was shifted to the late summer
during Year 7 (and for subsequent monitoring events). These changes in sampling
location and timing introduced variables that made inter-year comparisons more difficult
in Year 7. Year 8 monitoring represents the second year that data collection has occurred
in the late summer/early fall. As monitoring continues, additional data will allow for a
more accurate characterization of trends between years.
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0
FIGURES
0
4
0 500 1,000
ft
MT2 (42 ft)
MT5 (-126 ft.)
ff
--
4f'
JFA
SMA4
Legend
Ali
0 Marsh Stations (Continuous Sampling)
Figure 1. Original Transect Location Map 9 Back -Barrier Stations (Sampled b/n 2001-2007)
(2001 Aerial Photography) Change in marsh boundary from December 2001
to August 2008
Infaunal Sampling conducted at IVIT2, IVIT4, and MT6

tv
0

10
Figure 3. Analysis of Stem Density vs. Position Relative to Mason Creek (Year 8)
N
F
^L'
W
Q
n
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W
U)
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0
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^c
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45-

40-
35
30-1
N=30
t5 p = 0.7286
5 50 100 150 300
Distance from Mason Creek (ft)
10
North South
Position Relative to Mason Creek
Figure 4. Stem Density vs. Distance from Mason Creek
I0
I•
0
Figure 5. Analysis of Stem Density vs. Transect Number (Year 8)
55
E
ALA
W
Q 50
Cn
E
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CI) 45
y--
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/+ 40
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Q
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c
a)
0
a)
cn
1 2 3 4 5 6
Transect Number
Figure 6. Analysis of Stem Density (Pre-Project vs. Post-Project)
DO-
Do-
30-
70-
50-
50-
to-
)0-
0- --
N = 258
p = <0.0001
0
0 1 2 3 4 5 6 7 8
Year
0
I•
?0
Figure 7. Analysis of Height Index vs. Position Relative to Mason Creek (Year 8)
170 -
160
150
140
U) 130
120
N
0 110
100
X
N 90
C: 80
70
N 60
F- 50
m
4- 40
U)
30
North South
Position Relative to Mason Creek
Figure 8. Analysis of Stem Height Index vs. Distance from Mason Creek (Year 8)
1
160
150
140
70
0 Figure 9. Analysis of Height Index vs. Transect Number (Year 8)
1
W

M
> 1

O
E 1
N
-1..,
(n 1

O 1

X
(1)
1

C
a-
L

Z
_
F
a)
4-
W
Figure 10. Analysis of Stem Height Index (Pre-Project vs. Post-Project)
a?
cU

N
E
a?
U)

O

X
ai
.a
C

Z
_
E
a)

vO
0
1 2 3 4 5 6
Transect Number
0 1 2 3 4 5 6 7 8
Year
i•
0
0
0
Figure 11. Analysis of % Sand of Sediments vs. Position Relative to Mason Creek
U
L
D_
Figure 12. Analysis of % Sand of Sediments vs. Distance from Mason Creek
100
90
7

c
CU -
U)
80
C
N
U
L
?
?
W
0
70
60
N=30
p = 0.3718
5

50 100 150 300
Distance from Creek (ft)
North South
Position Relative to Mason Creek
I•
•
Figure 13. Analysis of % Organic Matter of Sediments vs. Position Relative to Mason Creek
L
N
(B
2
U
(B
C
N
U
^L'
^W
I..L
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
N=30
p = 0.0017
North South
Position Relative to Mason Creek
•
Figure 14. Analysis of % Organic Matter of Sediments vs. Distance from Mason Creek
12-
N=30
11- p = 0.3835
10-
9-
8-

6-
CU
f
4-
a)
3-
?
2-

?
`•,

1 -
0-
-1
-2-
5 50 100 150 300
Distance from Creek (ft)
0

Figure 15. Analysis of % Sand by Year (Pre-Project vs. Post-Project)
100,
90
40
80
07
C
N
U
L
Q 70
om _
60
•
50
C
? ` / Y?
N = 259
p = 0.4531
0 1 2 3 4 5 6 7 8
Year
Figure 16. Analysis of % Organic Matter by Year (Pre-Project vs. Post-Project)
N = 251
1° p=0.1433
L -
a)
y-+
C?
G
U -
(0 _
L _
O
U ?
L i
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0 - -
0 1 2 3 4 5 6 7 8
Year
0
I•
0
•
0
Figure 17. Stem Densities at Control Locations (300' away from marsh edge) by Year
1
N

a)
CL
Cn
E
a)
4-
Cn

0

a)

E
a)
U)
a0
30
7o rr
L
30
>o
40
30
'0
0
0

0 1 2 3 4 5 6 7 8
Year
Figure 18. Stem Heights at Control Locations (300' away from marsh edge) by Year
2oc
in
F-
0
0 100
X
a)
C
0)
.6
7-
E
0
U)
N=54
p = <0.0001

0 1 2 3 4 5 6 7 8
Year
0
0 APPENDIX A.
BENTH.IC INFAUNAL SU&MkRY OF FINDINGS
0
Monitoring of Benthic Faunal Communities associated with the
Mason Inlet Relocation Project - 2009 (Year 8) Sampling
Prepared by Troy Alphin
Research Associate, Center for Marine Science
University of North Carolina at Wilmington
Introduction
The health of estuarine habitats is often based on the provision of certain ecosystem
functions. Marsh habitats act as nurseries because they provide both refuge for early
juveniles of many species and because they provide areas for them to forage. In most
cases these species forage (or prey) upon small organisms (mostly macro invertebrates)
that live in or on the substrate surface or closely associated with the plant structures. The
investigation of these organisms and the communities they form is often difficult because
of their small size and highly variable abundance based on small scale spatial changes,
temporal fluctuation, and response to predators. The development of these macro
invertebrate communities is closely tied to the proper ecosystem function provided by
marsh systems. If there are not sufficient organisms to allow juvenile fishes to forage
they will leave the relative safety of the marsh habitat, potentially increasing the risk of
predation. It is possible that large scale changes in benthic macro-invertebrate
communities could lead to shifts in class strength of some species. Benthic infaunal and
epibenthic macrofauna are often studied to help evaluate the function of various
estuarine, marine, and aquatic habitats. Many of these organisms comprise a significant
portion of the diet of estuarine fishes and are critical to the maintenance and health of fish
populations. In many cases benthic organisms are the critical food resource for larval
and juvenile fishes. Since the life history stages of both predator (fish) and prey (infauna
and epifauna) are closely linked temporally, it is vital that benthic communities thrive
during periods that precede the recruitment of juvenile fish. In essence if the benthic
organisms are not present when juvenile fish move into the river, bay or sound, the
possibility of recruitment failure, for certain fish, increases.
Benthic infauna are those organisms that live within the sedimentary environment or on
the sediment surface, although organisms that are primarily on the sediment surface are
referred to as "epi-Benthic". In general when we refer to epi-fauna in the soft substrate
community we are referring to the more motile crustaceans and fishes, especially juvenile
finfish that may derive a significant portion of their diet from the benthos. The organisms
that comprise the majority of the benthic community are annelids (both polychaete and
oligochaete), bivalves, amphipods, isopods, and insects. Although other taxonomic
groups are often present, these groups tend to represent the numerical dominants for most
estuarine sites. These organisms demonstrate a variety of life history strategies, based on
feeding type and living position. While surface oriented species may be readily available
to bottom foraging fishes, deep burrowing forms are less like to be preyed upon.

0
This study focuses on the subgroup of benthic fauna considered macrofauna within the
size class of 500 microns (1000 microns= 1 millimeter) or greater. Most benthic
organisms in this size class are heavily preyed upon by larger finish and crustaceans.
These organisms tend to live 6 months to a 1 year (although there are some groups such as
bivalves that can live for a number of years). These organisms also tend to have
relatively low motility and once settled tend to move less than 5 meters over the course of
their lives. The benthic community provides a critical ecosystem role in transferring
energy to higher trophic levels because this group feeds primarily on algae and detritus
(although there are some predatory forms as well). The other main reason for studying
this group is based on their close relationship with the sediment, and different taxa will
respond to acute and chronic disturbances of this habitat in different ways. Monitoring of
benthic fauna is an important part of many environmental studies, including beach dredge
and fill operations, beach renourishment projects, and marsh restoration projects because
they provide a good indicator of both short and long term impacts and recovery. While
year to year changes (inter-annual variation) are natural acute and chronic impacts to the
habitat are better evaluated on a mulit-year basis when annual variation can be factored
out.
Sampling Design
This report covers the 2009 sampling period. Samples were collected along three marsh
transect locations during August 2009. As reported in the 2008 benthic summary, all
previous benthic assessments (2002-2007) were collected in November/ December but
starting in 2008 the sampling time period changed to August.
In the past some sampling locations have been relocated due to erosion or accretion along
the marsh edge. During the 2009 sampling period the MT2 and MT4 transects
experienced erosion requiring the relocation of MT2-5, MT2-50 and MT4-5. It should
also be noted that MT6 experienced accretion of sediments along the edge such that the
MT6-5 location is now - 30 ft from the marsh edge.
• Infaunal samples were collected using standard benthic cores, 10 cm diameter x 15 cm
deep. The sites sampled in the 2008 sampling periods included a series of marsh transect
locations (MT2, MT4 and MT6). The MT transects consisted of three replicate core
samples taken at each of three distances from the marsh edge (5, 150, and 300 feet into
the marsh) on each transect (though the exact edge location varied somewhat over time
with erosion or accretion).
All samples were fixed in 10% buffered formalin (formaldehyde derivative) solution with
rose Bengal dye added and later transferred to a 70% isopropanol preservative for storage
and processing. Samples were sieved through a 500 micron screen to remove fine
sediments and aid processing. All organisms retained were separated from the remaining
sediment and vegetative material using light microscopes and identified to the lowest
possible taxonomic level (generally species). As part of our standard quality control and
•
quality assurance procedures, identifications are subject to verification and a subset of
sorted samples are rechecked to ensure removal of all organisms. All newly identified
species and those that could not be identified to the species level are sent to authorities
for clarification. Diversity was calculated using the Shannon Diversity Index.
Community Description
A total of 49 taxa were collected during the 2009 sampling period (similar to previous
years). There were 22 taxa that represented 3% or more of the individuals collected at a
given site (Anurida maritime, Bezzia/Palpomyia, Curculionidae sp, Dolichopodidae sp.,
Gastropoda sp. (juvenile), Geukensa demissa, Hargeria rapax, Heteromastus filiformis,
Hydracarina sp., Lepidactylus dytiscus, Neanthes succinea, Nematoda sp., Nemertea sp.,
Neohaustorius schmitzi, Nereidae sp., Orchestia uhleri, Pseudonototanais sp. B,
Sphaeroma (quadridentaum), Tubificidae spp., Uca pugilator, Uca sp.).
Overall mean abundances were highly variable in 2009. Comparison among all sites
showed no significant difference among the sites and locations; this is due largely to the
high variability among sampling locations (figure 1). Species richness showed a similar
pattern to previous years with no differences among sites (figure 2), this is not surprising
since overall species richness seems low. The Shannon Diversity Index takes into
account number of taxa as well as species evenness. Comparison of mean diversity
among sites showed, as in previous years, low diversity at most sites (figure 3). Since
evenness is used to calculate species diversity and is itself a useful measure of species
distribution among sites, this information is presented in figure 4. Analysis of evenness
detected a marginal difference (F=3.14 p<0.5) but pair wise comparisons could not detect
any difference among locations. There was a high degree of variation among the major
taxonomic groups present at each site and the relative abundance of these groups by site
(table 1). Not surprisingly this variation follows the general trend among the dominant
species (figure 5-figure7). Most notably the edge locations tend to be dominated by the
amphipod taxa (Hargeria rapax, Neohaustorius schmitzi, and Orchestia uhleri) while the
interior sites tend to be dominated by oligochaetes, polychaetes, and tanaid fauana
(Heteromastus filiformis, Lepidactylus dytiscus, Neanthes succinea, Nereidae sp.,
• Pseudonototanais sp. B, and Tubificidae spp.).
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APPENDIX B.
SEPTEMBER 2009 SITE PHOTOGRAPHS
i•
•

Mason Inlet
Relocation Project
New Hanover County, NC

View of interior of MT1 transect
LMG
Site Photographs
September 2009
(Post-Construction Year 8)

(1) View of edge of Mt1 transect on the north side of Mason Creek
i•
0
(3) View of edge of relocated MT6 transect on south side of Mason Creek at low tide
(4) View of sampling location in interior of MT6 transect
•
Mason Inlet
Relocation Project
New Hanover County, NC
LMG
., ,iaFhaotn!t_vi oao?a
Site Photographs
September 2009
(Post-Construction Year 8)

I•
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(5) View of re-established MT6 transect on the south side of Mason Creek

Mason Inlet Site Photographs
Relocation Project LMG September 2009
New Hanover County, NC (Post-Construction Year 8)
is
(6) View of marsh edge on the south side of Mason Creek