20000008 Ver 1_Mitigation Report_20080222

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At,?LMG
LAND MANAGEMENT GROUP INC.
7W Environmental Consultants
February 21, 2008
TO: Ms. Joanne Steinhuis
NC Division of Water Quality
127 Cardinal Drive Extension
Wilmington, NC 28405
)00Lf 17116

2 2, 0 8
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RE: Mason Inlet Relocation Project - Biological Monitoring Report: December 2006 (Year 5)
Dear Joanne:
On behalf of New Hanover County (NC), Land Management Group, Inc. (LMG) is providing the requested
December 2006 (Year 5) Benthic Infaunal Report for the Mason Inlet Relocation Project. One (1) hard copy is
enclosed for your review and use. Please include this as an addendum to the full report for Year 5 that was
submitted in November 2007. Please contact our office if you need digital copies for distribution to other federal
agencies reviewing the project.
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(@Imqroup.net.
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Sincerely,
Land Management Group, l
anning
Environmental Scientist
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E R ('!?b R D M2. P
MAR 1 3 2008
,N^ STFJRMW,4TER BRANCt1.
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington,
NC 28402
Monitoring of benthic faunal communities associated with the Mason Inlet relocation
project - 2006 sampling •
Benthic Faunal Communities
Benthic infauna is the community of organisms that live within the sedimentary
environment or on the sediment surface, although organisms that live 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. Most benthic organisms tend to live 6 months to 1 year (although some taxa
such as bivalves may live 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. Depending on environment and dominant taxa this community tends to
respond relatively quickly to perturbations reflecting the average conditions at a location.
The overall abundance of benthic organisms and the stability/resilience of the community
can reveal much about the local environment and potential consequences to upper trophic
groups. A community consistently dominated by disturbance oriented taxa may indicate
persistent instability (either from actual sediment movement or potentially from
deposition of material on the substrate surface) in the sedimentary environment.
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 finfish and •
crustaceans. One of the primary reasons for studying this group is that the benthic
community provides a critical ecosystem role in transferring energy from algae and
detritus that most infauna feed upon (although there are some predatory forms as well) to
higher trophic levels. The other main reason for studying this group is based their close
relationship with the sediment and various taxa will respond differently to acute and
chronic disturbances of this habitat. Most tube forming taxa will thrive in more stable
areas with limited rates of sedimentation. Free burrowing forms however require less
compacted sediments and tend to dominate areas with greater sediment water content and
greater amounts of organic materials. Most benthic environments are composed of a
complex mosaic of sediment types influenced by local physical interactions, inputs from
surrounding habitats and terrestrial environments, and biotic interactions. Monitoring of
benthic fauna is an important part of many environmental studies, including beach dredge
and fill operations and beach renourishment projects and marsh restoration projects
because they provide a good indicator or both short and long term impacts and recovery.
Sampling Design
This report covers the 2006 sampling period for the post construction phase of the
Mason Inlet relocation project. This project was initiated in 2001 with a set of
preliminary samples collected in December 2001, prior to construction. The mason Inlet
relocation was completed in 2002, with post construction sampling being conducted
2002-2006. The samples reported here represent four sediment sites (S1-S4) and two
control sites (IV 1 and IV2) and three transects (MT2, MT4, and MT6) with three
• positions (5, 150, 300) on each transect. Each position indicates the distance from the
marsh edge. All samples for all sites were collected on a single day. The infaunal
sampling reported here represents community composition four years following inlet
relocation. All samples were collected at the same locations as previous samples to be
consistent. It should be noted here that in the 2006 report several of the transect sites
were marked as "old sites" however no such designation was indicated for the current
report. Both the S and IV sites seem to be sand dominated based on the presence of
Haustorid amphipods Neohaustorius schmitzi and the tanaid Lepidactylus dytisus these
species tend to be more common on sand dominated shorelines although L. dytisus builds
tubes and tends to associate with rhizomes. The marsh transect locations (MT2, MT4 and
MT6) should have all been marsh interior samples although MT2-5 and MT4-5
contained the barnacle Chthamalus fragilus, that tend to be found on exposed hard
substrate environments and Gemma gemma which is a small (2mm) brooding clam most
commonly found on open sand flat and low energy sandy beach environments. There
were four S subsites (S 1, S2, S3 and S4) and two IV sites (IV 1 and IV2). Each S and IV
subsite was sampled with three replicate core samples. 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).
Infaunal samples were collected using standard benthic cores, 10 cm diameter x
15 cm deep. All samples were fixed in 10% buffered formalin (formaldehyde derivative)
• solution with rose Bengal dye added and later transferred to a 50% isoproponol
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 Weiner Diversity Index.
2006 Community Description
A total of 51 taxa were collected during the 2006 sampling period (Arachnids and
terrestrial insects are excluded from this count as are harpacticoid copepods and
nematodes that are generally too small to be retained on a 500 micron mesh but are
probably present in the samples due to the amount organic material and not representative
of accurate densities. Polychaetes (segmented worms) were represented by 16 taxa (the
highest number of taxa among any group sampled), insects were represented by 8 taxa,
while amphipods were represented by 5 taxa and bivalves by 3 taxa (Table 1 to Table 5).
Gastropods were poorly represented, with most specimens lumped into the gastropods sp
classification, because of small size (> lmm) and poor condition. Overall the most
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numerous taxa were Hargeria rapax (Tanaid), Capitella Capitata (polychaete) and
tubificid (Oligochaete). •
The two sets of sand sites were characterized by lower species richness and lower
diversity (Table 5). Only 6 taxa were collected from the IV sites, while 9 were collected
from the S sites. This is a slight decline in species richness from the 2005 sampling
period. The S and IV sites were both dominated by the amphipod Neohaustorius schmitzi
although this is mainly due to the relatively high density of amphipods in station S3 and
IV 1. By and large most taxa present in the S and IV sites were represented by single
individuals.
In general two of the marsh transect sites (MT2 and MT4) were characterized by
higher species richness, greater mean abundances and slightly higher diversity
measurements than the sand dominated sites. A total of 26 taxa were collected from the
MT2 sites and 30 taxa from MT4 sites while only 14 taxa were collected from the MT6
sites. Species richness has declined in the MT6 consistently over the last three years.
The dominant taxa at MT2 were Capitella capitata and Tubificidae sp. (Table 2) MT4
was dominated by Capitella capitata, Dasyhelea sp., Hargeria rapax, and Tubificidae sp.
(Table 3). Densities of species in MT6 were overall low with no clear dominant species
(Table 4)
. Diversity takes into account both total abundance and relative proportion of
each taxa to the total abundance. For a typical back marsh area along the southeastern
coast of the United States a diversity that approaches or exceeds 1.0 would be considered is
good. As seen in previous sampling periods diversity at both marsh transect and sand
sites tended to be relatively low. However diversity showed slight increases in 2006 over
2005 for 4 of the 6 sites in the S and IV stations and at 6 or 9 sites for the transects.
Highest diversity was calculated for MT2-5 (H'=1.03) and lowest diversity was
calculated for the sand sites S3 and S4 (H'=0.30), due to low species richness and
evenness (Table 1).

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Table 5. Diversity and species richness by site for 2004, 2005 and 2006. Diversity is
calculated using Shannon Weiner index. Diversity is a measurement of species evenness
that incorporates relative abundance of individual species at a given site as well as the
number of species present. Species Richness represents the total number of taxa present.
Species richness presented here includes higher taxonomic groups for specimens that
were incomplete and for juveniles specimens that could not be reliably identified to lower
species level.
Site Mean Total Abundance Diversity Species Richness
2004 2005 2006 2004 2005 2006 2004 2005 2006
IV 1 4.0 8.33 19.67 0.184 0.286 0.36 4 3 3
IV 2 12.33 0.33 4.11 0.278 0 0.48 6 1 3
S 1 2.0 106.33 24.0 0.244 0.503 0.39 2 5 8
S2 15.33 16.0 6.33 0.573 0.613 0.77 6 8 8
S3 302.67 11.0 19.0 0.376 0.734 0.30 16 8 7
S4 13.33 6.67 0.67 0.346 0.077 0.30 6 5 2
MT2 5 50.33 25.0 23.56 0.628 0.908 1.03 20 14 17
MT2150 184.0 99.0 22.33 0.86 0.953 0.76 21 22 11
MT2 300 34.67 109.0 103.33 0.586 0.732 0.86 17 21 18
MT4 5 76.0 105.0 55.33 0.729 0.6 0.80 20 14 16
MT4150 111.33 180.67 271.33 0.382 0.63 0.94 13 13 22
MT4 300 141.67 112.0 163.33 0.51 0.858 0.53 21 20 12
MT6 5 10.0 4.0 1.67 0.277 0.559 0.58 7 4 4
MT6150 21.3 7.0 1.33 0.531 0.682 0.43 13 6 3
MT6 300 12.0 187.75 11.0 0.653 0.258 0.79 10 17 8
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