Prepared in cooperation with the Louisiana State University Agricultural Center 

Baseline Data for Evaluating the Development 

Trajectory and Provision of Ecosystem Services by 

Created Fringing Oyster Reefs in Vermilion Bay, 

Louisiana 

By Megan K. La Peyre, Lindsay Schwarting, and Shea Miller 

Open-File Report 2013–1053 

U.S. Department of the Interior 

U.S. Geological Survey 
ii 

U.S. Department of the Interior 

KEN SALAZAR, Secretary 

U.S. Geological Survey 

Suzette M. Kimball, Acting Director 

U.S. Geological Survey, Reston, Virginia: 2013 

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey 

Box 25286, Denver Federal Center 

Denver, CO 80225 

To learn about the USGS and its information products visit http://www.usgs.gov/

1-888-ASK-USGS 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual copyright 

owners to reproduce any copyrighted materials contained within this report.

Suggested citation: 

La Peyre, M.K., Schwarting, Lindsay, and Miller, Shea, 2013, Baseline data for evaluating development 

trajectory and provision of ecosystem services of created fringing oyster reefs in Vermilion Bay, 

Louisiana: U.S. Geological Survey Open-File Report 2013–1053, 43 p. 
iii 

Acknowledgments 

We thank the many people who were critical in completing field work, processing 

samples in the lab, and providing boats and boat support including Louisiana State University 

Agricultural Center students and employees: Gary Decossas, Bran Wagner, Phil Westbrook, 

Aaron Honig, Austin Humphries, Steve Beck, Ben Eberline, Molly Rybovich, Jessica Furlong, 

Laura Brown, Mark Miller, Brandon Edwards, Cheryl Duplechain, Sandra Casas, Jerome La 

Peyre, Jon Risinger, Steve Hall; Louisiana Department of Wildlife and Fisheries employees: Paul 

Cook, Heather Finley; Oratech: Tyler Ortego; and The Nature Conservancy staff: Cindy Brown, 

Amy Smith-Kyle, Seth Blitch, Bryan Piazza, and Richard Martin. We thank Darrel Anders 

(USGS-NWRC) for boat support. Thanks to Dr. Stephen Scyphers and Dr. Lesley Baggett for 

comments that improved this report. This study was performed under the auspices of Louisiana 

State University IACUC protocols #08-005 and 11-006. Funding for this work was through a 

contract from The Nature Conservancy of Louisiana to Louisiana State University Agricultural 

Center. 
iv

Contents

Abstract ......................................................................................................................................................................... 1

Introduction.................................................................................................................................................................... 2

Study Area..................................................................................................................................................................... 3

Reef Construction and Sampling Schedule ................................................................................................................... 7

Project Methods............................................................................................................................................................14

Shoreline Stabilization and Adjacent Marsh Vigor ....................................................................................................14

Reef Sustainability ....................................................................................................................................................14

Water Quality ............................................................................................................................................................17

Habitat Enhancement ...............................................................................................................................................17

Analyses ...................................................................................................................................................................17

Results and Discussion ................................................................................................................................................18

Vermilion Cove..........................................................................................................................................................18

Shoreline Stabilization...........................................................................................................................................18

Reef Sustainability.................................................................................................................................................21

Environmental Variables .......................................................................................................................................23

Habitat Enhancement............................................................................................................................................26

Southwest Pass ........................................................................................................................................................34

Shoreline Stabilization...........................................................................................................................................34

Reef Sustainability.................................................................................................................................................36

Environmental Variables .......................................................................................................................................36

Habitat Enhancement............................................................................................................................................38

Summary and Conclusions...........................................................................................................................................41

Cited References..........................................................................................................................................................42

Figures

Figure 1. Map of study area located in Vermilion Bay, Louisiana ............................................................. 4

Figure 2. Location of 10 study sites (8 reef and 2 reference) along the shoreline by Vermilion Cove, 

Louisiana.... .................................................................................................................................................. 5

Figure 3. Location of 6 study sites (4 reef and 2 reference) within Southwest Pass, Louisiana................ 6

Figure 4. Layout of artificial reef bases and reef design.......................................................................... 11

Figure 5. Reefsicles created and installed in Vermilion Cove for monitoring oyster recruitment............. 16

Figure 6. Shoreline displacement and change in soil volume in Vermilion Bay, Louisiana ..................... 19

Figure 7. Mean aboveground and belowground vegetative biomass of reference and treatments at 

Vermilion Cove, Louisiana, sites.................................................................................................................. 20

Figure 8. Mean growth and cumulative mortality of oysters deployed in cages adjacent to Vermilion 

Cove, Louisiana, intertidal reef in 2011 and 2012........................................................................................ 22

Figure 9. Overall mean salinity of all study sites at Vermilion Cove and Southwest Pass, Louisiana, 

plotted with salinity data from the nearest continuous data recorder maintained by the State of 

Louisiana.... ................................................................................................................................................ 24

Figure 10. Daily mean water levels at Vermilion Cove, Louisiana, from January 2010 to June 2012 ... 25

Figure 11. Mean catch per unit effort and number of species caught with gill nets, seine, and cast nets 

at reference, subtidal, subtidal 2, intertidal, and intertidal-gap reefs at Vermilion Cove, Louisiana.............. 27
v 

Figure 12. Mean aboveground and belowground vegetative biomass of reference and treatments at 

Southwest Pass, Louisiana, sites ................................................................................................................ 35

Figure 13. Daily mean water levels at Southwest Pass, Louisiana, from January 2010 to June 2012.. 37

Figure 14. Mean catch per unit effort and number of species caught with gill nets, seines, and cast-nets 

at reference, subtidal, and subtidal 2 sites at Southwest Pass, Louisiana................................................... 39

Tables

Table 1. General timeline of preconstruction, construction, and postconstruction activities for research 

sites in Vermilion Cove and Southwest Pass, Louisiana ............................................................................... 8

Table 2. Schedule of actual sampling activities for reef and reference sites at Southwest Pass and 

Vermilion Cove in Vermilion Bay, Louisiana ................................................................................................ 13

Table 3. Range of water quality parameters measured at reef and reference sites at Vermilion Cove, 

Louisiana, across all dates and construction statuses ................................................................................. 23

Table 4. Mean catch per unit effort for gill net at reference and reef sites at Vermilion Cove, Louisiana. 

“Total” indicates the overall number of individuals....................................................................................... 28

Table 5. Mean catch per unit effort for seine at reference and reef sites at Vermilion Cove, Louisiana. 

“Total” indicates the overall number of individuals....................................................................................... 30

Table 6. Mean catch per unit effort for cast net throw at reference and reef sites at Vermilion Cove, 

Louisiana.... ................................................................................................................................................ 32

Table 7. Density of species collected on substrate trays deployed near reference, subtidal, intertidal, 

and intertidal‐gap sites at Vermilion Cove, Louisiana.................................................................................. 33

Table 8. Mean catch per unit effort for gill net at reference and reef sites at Southwest Pass, Louisiana, 

sites........... ................................................................................................................................................ 38

Table 9. Mean catch per unit for seine at reference and reef sites at Southwest Pass, Louisiana ........ 40

Table 10. Mean catch per unit effort for cast net throws at reference and reef sites at Southwest Pass, 

Louisiana.... ................................................................................................................................................ 41
vi

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

meter (m) 1.094 yard (yd) 

Area

square meter (m2) 0.0002471 acre 

square meter (m2) 10.76 square foot (ft2) 

Volume

liter (L) 33.82 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

cubic centimeter (cm3) 0.06102 cubic inch (in3) 

liter (L) 61.02 cubic inch (in3) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32 

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or in micrograms per liter (μg/L).
Baseline Data for Evaluating the Development 

Trajectory and Provision of Ecosystem Services by 

Created Fringing Oyster Reefs in Vermilion Bay, 

Louisiana 

By Megan K. La Peyre,1 Lindsay Schwarting,2 and Shea Miller2

Abstract 

Understanding the time frame in which ecosystem services (that is, water quality 

maintenance, shoreline protection, habitat provision) are expected to be provided is important 

when restoration projects are being designed and implemented. Restoration of three-dimensional 

shell habitats in coastal Louisiana and elsewhere presents a valuable and potentially selfsustaining approach to providing shoreline protection, enhancing nekton habitat, and providing 

water quality maintenance. As with most restoration projects, the development of expected 

different ecosystem services often occurs over varying time frames, with some services provided 

immediately and others taking longer to develop. 

This project was designed initially to compare the provision and development of 

ecosystem services by created fringing shoreline reefs in subtidal and intertidal environments in 

Vermilion Bay, Louisiana. Specifically, the goal was to test the null hypothesis that over time, 

the oyster recruitment and development of a sustainable oyster reef community would be similar 

at both intertidal and subtidal reef bases, and these sustainable reefs would in time provide 

similar shoreline stabilization, nekton habitat, and water quality services over similar time 

frames. Because the ecosystem services hypothesized to be provided by oyster reefs reflect longterm processes, fully testing the above-stated null hypothesis requires a longer-time frame than 

this project allowed. As such, this project was designed to provide the initial data on reef 

development and provision of ecosystem services, to identify services that may develop 

immediately, and to provide baseline data to allow for longer-term follow up studies tracking 

reef development over time. 

Unfortunately, these initially created reef bases (subtidal, intertidal) were not constructed 

as planned because of the Deepwater Horizon oil spill in April 2010, which resulted in reef 

duplicates being created 6 months apart. Further confounding the project were additional 

construction and restoration projects along the same shorelines which occurred between 2011 

and June 2012. Because of constant activity near and around the reefs and continuing 

construction, development trajectories could not be compared among reef types at this time. This 

report presents the data collected at the sites over 3 years (2010-2012), describing only 

conditions and trends. In addition, these data provide an extensive and detailed dataset 

 

1

U.S. Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, School of Renewable Natural 

Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803. 2

School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803. 
2 

documenting initial conditions and initial ecosystem changes which will prove valuable in future 

data collection and analyses of reef development at this site. 

Data collection characterized the local water quality conditions (salinity, temperature, 

total suspended sediments, dissolved oxygen, chlorophyll a), adjacent marsh vegetation, soils, 

and shoreline position along the project shoreline at Vermilion Bay. During the study, marsh 

vegetation and soil characteristics were similar across the study area and did not change over 

time. Shoreline movement indicated shoreline loss at all sites, which varied by reefs. Water 

quality conditions followed expected seasonal patterns for this region, and no significant 

nonseasonal changes were measured throughout the study period. Despite oyster recruitment in 

fall 2010 and 2011, few if any oysters survived from the 2010 year class to 2012. At the last 

sampling of this project, some oysters recruited in fall 2011 survived through 2012, resulting in 

an on-reef density of 18.3 ± 2.1 individuals per square meter (mean size: 85.6 ± 2.2 millimeters). 

Because project goals were to compare reef development and provision of ecosystem services 

over time, as well as many of the processes identified for monitoring reflect long-term processes, 

results and data are presented only qualitatively, and trends or observations should be interpreted 

cautiously at this point. Measurable system responses to reef establishment require more time 

than was available for this study. These data provide a valuable baseline that can be ultimately 

used to help inform site selections for future restoration projects as well to further investigate the 

development trajectories of ecosystem provision of created reefs in this region. 

Introduction 

Restoration of three-dimensional shell habitats in coastal Louisiana presents a valuable 

and potentially self-sustaining approach to providing shoreline protection, enhancing nekton 

habitat, and maintaining water quality (Coen and others, 1999, 2007; Peterson and others, 2003; 

Scyphers and others, 2011). As with most restoration projects, the development of expected, 

different ecosystem services (that is, water quality maintenance, shoreline protection, habitat 

provision) often occurs over varying time frames with some services provided immediately, 

whereas others may take as long as two decades to develop (that is, Odum, 1969; Craft and 

others, 1999; La Peyre and others, 2008). In order to accurately account for service provision and 

to properly evaluate the success of a restoration project, full understanding of the time-frame in 

which ecosystem services are expected to function is important. The development and ecological 

trajectory of restored ecosystems has long been investigated and borrows heavily from studies on 

ecological succession, community ecology, and ecosystem development (Odum, 1969). 

Although numerous studies have documented marsh restoration development trajectories, few 

studies that we are aware of have addressed the development trajectories of functional oyster 

reefs within coastal waters. 

This project was designed initially to compare the provision and development of 

ecosystem services over time between created subtidal and intertidal oyster reefs. Specifically, 

the goal was to test the null hypothesis that over time, the recruitment and development of a 

sustainable oyster reef community would be similar at both intertidal and subtidal reef bases, and 

these sustainable reefs would in time provide similar shoreline stabilization, nekton habitat, and 

water quality services. Because the ecosystem services hypothesized to be provided by oyster 

reefs reflect long-term processes, fully testing the above-stated null hypothesis requires a longertime frame than this project allowed. As such, this project was designed to provide the initial 

data on reef development, as well as provision of ecosystem services, to allow for longer-term 

follow-up studies tracking reef development over time. 
3 

The Nature Conservancy, working with local landowners (Audubon Society) and 

construction and engineering companies, developed and implemented the artificial reef creation. 

From 2010 through 2012, we collected preconstruction and postconstruction physiochemical and 

biological data to quantify changes in reefs and to identify their provision of ecosystem services 

over time. Although the initial project design called for comparison of subtidal and intertidal 

reefs with reference sites, all duplicated along the same shoreline, many factors contributed to 

continued project changes. The Deepwater Horizon oil spill, along with the restoration 

community’s desire to continue to implement further artificial reef segments, resulted in the 

addition of four subtidal reef segments and two reference sites along the shoreline of Southwest 

Pass, La., immediately east of the Vermilion Cove shoreline, and the addition of duplicate, new 

intertidal (intertidal gap) and new subtidal (subtidal 2) shoreline segments along Vermilion 

Cove. This rolling construction activity resulted in mismatched sample dates, uneven reef ages, 

and an inability to follow a controlled experimental design. As a result, this report provides an 

overview and description of reef and shoreline specific soil, marsh, and water quality 

characteristics, shoreline movement, oyster recruitment and survival, and nekton use associated 

with each reef segment over the last 3 years. 

Presented herein are the data collected between January 2010 and October 2012, which 

include preconstruction data, and postconstruction monitoring, with installation dates for 

different units ranging from April 2010 to June 2012. These data provide a detailed overview of 

reef recruitment, marsh status, shoreline movement, and nekton abundances within the 

experimental area. Because 5 years of postconstruction data are generally recommended to fully 

assess the effectiveness of reef restoration (http://www.oyster-restoration.org/scsg04/ 

SCSG04.pdf; accessed February 1, 2013), these data present only a very short-term view of the 

impact of the projects (from 6 to 20 months [mo] after construction). 

Study Area 

This project was located in Vermilion Bay, La., in two locations adjacent to land owned 

by the Audubon Society (Rainey Refuge) (fig. 1). One location is situated facing south 

(Vermilion Cove) in protected, shallow waters (fig. 2). The Vermilion Cove shoreline is 

composed of silt/clay and oyster shell fragments. The area in front of the shore has a low depth 

profile with the entire bay averaging less than 1 (m) water depth under mean water conditions. 

Shoreline profiles range from receding beach/vegetation fronts to shallow cut-bank edges (20-40 

centimeters [cm]). The other location (Southwest Pass) is located on a northeast-facing shore 

along a busy navigation channel with comparatively swift water and a large fetch (fig. 3). 

Southwest Pass sites have a relatively steep edge and are exposed constantly to large workboat 

wakes and wind-generated waves. Both sites are located adjacent to one of Louisiana’s public 

oyster seed grounds although the area has not been highly productive for oyster harvest in recent 

years because of increased input of freshwater from the Atchafalaya River, which results in low 

salinity during the summer months in many years 

(http://www.wlf.louisiana.gov/sites/default/files/pdf/page_fishing/32695-

Oyster%20Program/2011_oyster_stock_assessment.pdf; accessed February 1, 2013). 
4 

Figure 1. Map of study area located in Vermilion Bay, Louisiana. The oyster reefs were placed adjacent to shorelines in So

Vermilion Cove.
5 

Figure 2. Location of 10 study sites (8 reef and 2 reference) along the shoreline by Vermilion Cove, Louisiana. Each reef co

meters (m) long and a minimum of 75 m apart. 
6 

Figure 3. Location of 6 study sites (4 reef and 2 reference) within Southwest Pass, Louisiana. Reefs are 68.5-meters (m) lo

75 m between each reef. 
7 

Reef Construction and Sampling Schedule 

Originally established as a controlled, duplicated designed experiment, because of 

funding opportunities available to the restoration community for specific projects along the exact 

same shoreline of this project, the project evolved significantly with continued restoration and 

creation activities along the project shorelines (table 1). The continual activities within the 

project area between March 2010 and June 2012, along with mismatched construction caused by 

the Deepwater Horizon oil spill, resulted in our inability to statistically compare sites or to draw 

any conclusions; we do, however, present a valuable baseline dataset for all of the activities that 

occurred within our study area. 
8 

Table 1. General timeline of preconstruction, construction, and postconstruction activities for research sites in Vermilion Cov

Louisiana. Multiple sample events occurred in SPR2011, SUM2011, and SPR2012. Reference sites at Vermilion Cove apreconstruction and postconstruction because of the wide range of construction dates and the loss of the original sample

because of placement of reefs on the reference site. 

[SPR, March-May; SUM, June-August; FAL, September-November; WIN, December-February] 

SPR2010 SUM2010 FAL2010 WIN2010 SPR2011 SUM2011 FAL2011 WIN2011 SPR20

Vermilion Cove 

Subtidal (T1) 

Presconstruction X 

Construction REP A REP B 

Postconstruction X X X X 

Intertidal (T2) 

Presconstruction X 

Construction REP A REP B 

Postconstruction X X X X 

Intertidal-gap (T3) 

Presconstruction X 

Construction REP A/B 

Postconstruction X X X 

Subtidal 2 (T4) 

Presconstruction X 

Construction REP A

Postconstruction 

Reference (REF) 

Sampling X X X 
9 

Table 1. General timeline of preconstruction, construction, and postconstruction activities for research sites in Vermilion Cov

Louisiana. Multiple sample events occurred in SPR2011, SUM2011, and SPR2012. Reference sites at Vermilion Cove a

preconstruction and postconstruction because of the wide range of construction dates and the loss of the original sample

because of placement of reefs on the reference site.—Continued 

 [SPR, March-May; SUM, June-August; FAL, September-November; WIN, December-February] 

Southwest Pass 

Subtidal (T1) 

Presconstruction X 

Construction REP 

Postconstruction 

Subtidal 2 (T4) 

Presconstruction X 

Construction REP 

Postconstruction 

Reference (REF) 

Sampling X 
10 

This project was initiated in Vermilion Cove with three treatments, each duplicated. Two 

reference shoreline segments, two created subtidal reef segments, and two created intertidal reef 

segments were identified with a minimum of 75 m between each segment. The Nature 

Conservancy contracted with a local consulting company to create reefs by using either a single 

layer (subtidal), or a double layer (intertidal) of OysterbreakTM rings (fig. 4). In April 2010, the 

first duplicate of each reef treatment (hereinafter subtidal Rep A; intertidal Rep A) was 

constructed. Further reef placement was stopped because of the Deepwater Horizon oil spill, and 

access to sites was highly restricted. In October 2010, construction of the second replicate of 

each treatment was completed (hereinafter subtidal Rep B; intertidal Rep B). This 6-mo 

difference in reef creation dates prevented us from examining reef development trajectories by 

using the designed replicates as originally planned. 
11 

Figure 4. Layout of artificial reef bases and reef design. A, View of subtidal artificial reef substrate bases during very low wa

double wide, single height layer of rings placed 30 meters off the shoreline. Subtidal rings are 50.8 centimeters (cm) tall, 

rings are 61.0 cm tall. B, View of intertidal artificial reef substrate bases; intertidal substrates consist of a double ring laye

by a single ring layer. Intertidal design is continuous; intertidal gapped (shown) is missing every fifth and sixth top ring. 
12 

Further project changes came during 2011 and 2012 with additional construction of 

artificial reefs along the same shoreline. In June 2011, duplicate intertidal gapped reefs were 

created. Intertidal- gap consisted of a double layer of OysterbreakTM rings, with the fifth and 

sixth top ring missing to create gaps for fish passage. This new set of reefs was placed on the 

original reference sites, and we established new reference sites outside the construction area. In 

June 2011, the original subtidal and intertidal reefs were lengthened so that all six constructed 

reef treatments were of equal length (68.5 m). Again, these changes resulted in impacts to our 

study sites because of construction activities and in substitution of our original reference sites. 

In March 2012, two more segments of the subtidal reef of similar length were constructed 

at Southwest Pass; in June 2012, duplicate reef segments of subtidal 2 reef (similar to original 

subtidal reef but 10 cm taller) were built in Vermilion Cove and Southwest Pass, resulting in an 

addition of six new reef segments and associated reference sites at Southwest Pass. A timeline of 

preconstruction and postconstruction sampling is outlined in tables 1 and 2. All sites had three 

randomly identified sample points along the reef length where sampling occurred. 
13 

Table 2. Schedule of actual sampling activities for reef and reference sites at Southwest Pass and Vermilion Cove in Vermil

SPR2010 SUM2010 FAL2010 WIN2010 SPR2011 SUM2011 FAL2011 WIN2011 SPR2

Shoreline X X X X Survey X Vegetation X X X X X X Soils X X X X X X Water quality X X X X X X X Nekton (transient) X X X X X Nekton (resident) X Oysters X X X X X X X X X Recruitment X 
14 

Project Methods 

Shoreline Stabilization and Adjacent Marsh Vigor 

Shoreline stabilization was measured following Meyer and others (1997) and Piazza and 

others (2005). At each sample point (three along each experimental reef or reference), five 

permanent base stakes were located in the marsh. A tape measure was used to determine the 

distance from the base stake to the shoreline edge. Shoreline edge is defined as the farthest 

waterward extent of the wetland macrophytes. To ensure consistent measurements, shoreline 

edge was measured along a set compass heading. 

To measure change in soil volume and shoreline slope change, a reference (Vermilion 

Cove) and one intertidal reef site (intertidal Rep A) were selected for detailed transect surveys by 

using a TOPCON GTS-226 electronic total station. Preconstruction (reef: November 2010; 

reference: February 2011) and postconstruction (both Nov 2012) transects (five, 35 m) running 

from on the marsh perpendicular into the water were completed, recording elevation every 1 m 

along set compass points and resulting in more than 60 point measurements. Different 

preconstruction dates for reference are due to the movement of our reference site. Changes in 

shoreline slope and soil volume located behind the reef were calculated by using the Surfer 8.03 

Surface Mapping System. Surfaces created from separate samplings were overlaid, and a change 

in sediment volume (cm3 mo-1) based on elevations was calculated through Surfer. 

Aboveground and belowground vegetation density and biomass, and soil percent organic 

matter and bulk density were quantified in triplicate at each sample point. At each sample point, 

triplicate quarter meter quadrats were haphazardly thrown to land within 1 m of the shoreline 

edge. Percentage of vegetative cover by species was recorded. All aboveground biomass was 

removed, returned to the lab at the Louisiana State University (LSU) AgCenter and quantified in 

the laboratory by drying to a constant biomass (gram [g]), and recording biomass by species. 

Within each quadrat, duplicate 5 x 15 cm cores were collected. One core was used to quantify 

belowground vegetative biomass by rinsing all sediment through a 3-mm sieve, and drying 

vegetative material to a constant biomass (g). The second core was used to determine percentage 

of soil organic matter by using loss on ignition in a muffle furnace. Bulk density was also 

calculated from these cores prior to firing in the muffle furnace. Bulk density is calculated as 

grams per cubic centimeter. 

Reef Sustainability 

To better understand the dynamics of reef sustainability, oyster growth, mortality, 

condition, and Perkinsus marinus (Dermo) infection intensities were measured in experimental 

bags placed adjacent to the reefs. In 2011, two bags of 100 2.5-cm oysters spawned at the LSU 

Sea Grant Oyster Hatchery were placed adjacent to the reef. In 2012, five bags of 100 2.5-cm 

oysters spawned at the LSU Sea Grant Oyster Hatchery were placed adjacent to the reef. Size 

and mortality were measured bimonthly, and disease and condition of 15 oysters were measured 

bimonthly. Cumulative mortality was calculated for each year, and growth rates were calculated 

by using shell length (GR = (SLt- SLt-1)/(# days*30)), where GR = growth rate; SL = shell 

length; and t = time). Growth rates were standardized to a 30-day month. These data are valuable 

in explaining on-reef observations of oyster population dynamics. 
15 

Because of difficulties encountered in sampling from the created reefs on submerged 

reefs in turbid waters, we established minireef prototypes, referred to as “reefsicles,” at the 

Vermilion Cove site. These reefsicles consisted of small oysterkrete blocks epoxied to PVC 

poles and placed off-bottom (fig. 5). These reefsicles allowed us to track oyster recruitment and 

growth on the oysterkrete substrate by removing the reefsicles from the water to count and 

measure oysters. Nine reefsicles were placed behind the intertidal reef at Vermilion Cove in 

April 2011; of these 9 reefsicles, 3 were covered in predator exclusion cages in order to account 

for differences in oyster populations which may be attributed to predation mortality. Reefsicles 

were checked in October 2011 for recruitment and then removed completely in October 2012 for 

analysis. Any oyster recruitment was counted and measured. Because of the conclusion of reef 

construction in June 2012, and final sampling in August 2012 at Southwest Pass, no reefsicles 

were set out at this location. 
16 

Figure 5. Reefsicles created and installed in Vermilion Cove for monitoring oyster recruitment. Clean oysterkrete material w

poles, which were inserted in the sediment so that the oysterkrete block was off the bottom. Reefsicles were constructed 

removed for analysis in October 2012.
17 

Water Quality 

Temperature (degrees Celsius [°C]), salinity, dissolved oxygen (milligrams per liter [mg 

L-1]) were measured every field visit by using a YSI model 556 water quality meter (Yellow 

Springs Instruments, Ohio) at each sample point. Water clarity was measured by using a secchi 

disk (cm). Furthermore, two opaque bottles of water were collected at 0.5 m below the surface, 

and immediately adjacent to the reef, placed on ice, and taken back to the lab to be processed for 

total organic matter, total inorganic matter (mg L-1), and chlorophyll a (micrograms per liter [μg 

L-1]). Continuous data from the nearest continuous data recorder were downloaded, and discrete 

temperature and salinity values compared; hourly water-level data from the recorder were also 

used to calculate reef exposure times (LOCPR, 2012). 

Habitat Enhancement 

Nekton (fish and invertebrates) recruitment to and use of the constructed reef structures 

were assessed by using four gear types. Gill nets were used to capture the large, transient fish 

community. The 11-m experimental gill nets consisted of four panels, each 2.7 x 1.8 m and with 

mesh sizes 3.8, 5.1, 6.4, and 7.6 cm. The gill nets were placed perpendicular to the reefs, on the 

seaward side of the reefs, and soaked for 1 hour. All gill net samples were processed in the field 

by recording species identity, total length, and biomass. Time of day and water quality 

measurements were taken with each sample. Samples were taken during daylight hours. 

To characterize the juvenile and resident nekton communities, five 2.4-meter (m) cast net 

samples were taken at each segment in the area between the reef and the marsh vegetation. Two 

10-m seine pulls by using a 3-m bag seine (3-mm mesh) near the marsh edge and near the reef 

structure were collected. All cast net and seine samples were bagged, placed on ice, and returned 

to the lab for further processing which involved species identification and measurement of total 

length and weight by species. 

Postconstruction resident communities at Vermilion Cove reefs were examined by 

deploying substrate trays filled with oyster shell in 2010, and again in 2011 and 2012. Trays 

were deployed at all sites in 2010 on the south side of the reefs, but we experienced a high loss 

of trays. In August 2011, trays were deployed adjacent to the reefs and at all reference sites and 

allowed to sit for 3 weeks before collection of all trays. This deployment was repeated in July 

2012. Because of the impracticality of using nets to capture cryptic species that live within the 

complex oyster reef matrix, trays were used to characterize the smaller fish and invertebrate 

communities that are known to reside and frequent healthy reefs (Lehnert and Allen, 2002; 

Plunket and La Peyre, 2005; Yeager and Layman 2011). Each tray (0.22 m2

) was modified by 

attaching a drawstring bag net with fine mesh (2.6 mm2

). The sides of this net were gathered at 

the base of the tray while it was deployed, and prior to retrieval, the net was drawn tight to 

enclose the tray contents before bringing the tray to the surface, preventing the escape of more 

mobile organisms (Beck, 2011). All organisms were placed in sample bags and put on ice for 

transport to the laboratory at LSU where they were processed and species identification and total 

length and weight (g dry weight) were recorded. Density of organisms was calculated and the 

community described. 

Analyses 

Because of major differences in site environment and reef construction, Vermilion Cove 

and Southwest Pass are presented separately. For Vermilion Cove samples, because of continual 
18 

construction from March 2010 through June 2012, data are presented and described qualitatively 

only. No direct comparisons are made because of the number of confounding factors making 

statistical comparisons, or direct comparisons with replicates, impossible. 

Although sampling was of a very short time frame, Southwest Pass sediment and 

vegetation samples were analyzed, but treatments were constructed in March and June, and 

postconstruction samples are from June and July of the same year. By using a two-factor analysis 

of variance (ANOVA), we examined preconstruction and postconstruction and treatment 

differences (SAS; PROC GLIMMIX; factors:TIME: pre and post; TREATMENT: reference, 

subtidal, subtidal 2). When results were significant, a Tukey’s test was used to identify 

significant differences. Aboveground and belowground vegetation biomass were log-transformed 

to achieve normality. Log-transformed nekton data (CPUE, richness) were analyzed by using a 

one-factor ANOVA (TREATMENT) with postconstruction data collected in summer 2012 only. 

Unless indicated otherwise, mean and standard errors are reported for all variables. 

Results and Discussion 

Vermilion Cove 

Shoreline Stabilization 

All sites experienced shoreline movement during the period of measurement, 

postconstruction, with the reference sites retreating a mean of 12.2 ± 7.6 cm mo-1, and reef sites 

retreating an average of 6.5 ± 3.1cm mo-1. Within reef sites, there were differences in mean 

retreat with subtidal sites retreating 14.2 ± 3.6 cm mo-1 and the two intertidal treatments 

retreating an average of 4.1± 2.7 cm mo-1 (fig. 6). Survey results of just one reference (February 

2011–November 2012) and one intertidal reef site (intertidal Rep A; Nov 2010–Nov 2012) show 

a larger decrease in soil volume at the reference site (0.18 cm3 m-1 mo-1) compared to the 

intertidal reef site (0.02 cm3 m-1 mo-1) (fig. 6). There was minimal change in slope at either site. 
19 

Figure 6. Shoreline displacement and change in soil volume in Vermilion Bay, Louisiana. A, Shoreline displacement (centim

mo-1]; 30-day month was used) for reference and reef treatments postconstruction (June 2011-July 2012). B, Change in 

reef and shoreline based on differences in elevation and slopes shown in graphs. Only one treatment (gray) and one refe

surveyed. 
20 

Overall, mean percentage of vegetative cover across all Vermilion Cove sites was 38.3 

percent (± 2.5). Dominant vegetative species at all sites was black needlerush (Juncus 

roemerianus) (27.3 ± 3.0 percent) and smooth cordgrass (Spartina alterniflora) (9.4 ± 1.5 

percent). Other species detected at sites include Distichlis spicata, Spartina patens, Phragmites 

australis, and Ipomoea sagittata. Across all Vermilion Cove sites, aboveground vegetative 

biomass was 800.6 ± 54.0 g m-2 (fig. 7). Total belowground vegetative biomass was 295.2± 25.4 

g m-2 (fig. 7). 

Figure 7. Mean (standard error) aboveground and belowground vegetative biomass (grams per square 

meter [g m-2]) of reference and treatments at Vermilion Cove, Louisiana, sites. Preconstruction samples 

for subtidal, intertidal, and intertidal-gap samples were collected in spring 2010, whereas 

preconstruction samples for subtidal 2 were collected in summer 2011. Reference represents all 

reference samples collected from fall 2010 through fall 2012. 

Percentage of organic matter and bulk density were significantly correlated, so only 

percentage of organic matter is presented. Overall mean percentage of organic matter across all 

Vermilion Cove sites was similar, averaging 3.6 ± 0.1 percent. 
21 

Reef Sustainability 

Oyster growth cages indicated slow growth and relatively high mortality in both 2010 

and 2011. In 2010, oysters experienced 71 percent mortality, with mean growth of remaining 

oysters at 3.0 mm mo-1 during spring 2010. No spat (young, immature oysters < 25 mm shell 

height) recruitment was detected until fall 2010, when all constructed reefs recruited spat with an 

estimated density of 300 individuals m-2, and ranging in size from 10 to 50 mm in November 

2010. Barnacles, algae, and mussels were evident on the reefs in the fall as well. 

In 2011, cumulative oyster mortality was 89 percent, and mean growth for the year was 

1.2 mm/mo (fig. 8). Despite the settlement noted in November 2010, no 1-year-old oysters were 

identified on the reefs in October 2011 indicating no survival. Reefsicles deployed in March 

2011 were checked for recruitment in October 2011. Only five individuals with a mean size of 

42.5 ± 10.5 mm were noted across nine reefsicle blocks; this size class suggests 2011 recruitment 

year class oysters only. Mortality from disease was not likely because infection of oysters by the 

parasite Perkinsus marinus was minimal (399.4 ± 165.0 spores g-1) during 2011.
22 

Figure 8. Mean growth (± standard error) and cumulative mortality of oysters deployed in cages adjacent to Vermilion Cove

reef in 2011 and 2012.
23 

In 2012, mean oyster growth was 1.8 mm mo-1 and cumulative mortality was 3 percent 

(fig. 8). The prevalence of infection by P. marinus in sampled oysters was moderate (53-80 

percent); however, mean overall infection levels were extremely low (1,972.1 ± 1,790.9 spores g -1

). 

Reefsicles placed adjacent to one of the intertidal reefs supported healthy recruitment of 

live oysters (fig. 5). All nine reefsicle blocks installed in March 2011 were recovered in October 

2012 with visible recruitment. Predator-exclusion cages were not recovered and were likely lost 

because of weather or wave action. Overall, the reefsicles had a mean oyster density of 18.3 ± 

2.1 individuals m-2. Attached oysters were a mean size of 85.6 ± 2.2 mm in length indicating that 

in 2012, and possibly fall 2011, recruited oysters were surviving and growing. 

Environmental Variables 

Water quality parameters are reported as ranges across all dates and treatment types 

(table 3). At each site, temperature, dissolved oxygen, clarity, salinity, total particulate matter, 

and chlorophyll a varied as expected by season and year. Because of the proximity of sites, no 

differences were expected between sites or treatments, and data are presented as overall ranges 

and means. Salinity measurements were comparable to continuous data collected by Coastal 

Reference Monitoring System (CRMS0541; LOCPR, 2012) (fig. 9). Daily mean water levels 

collected by CRMS0541 from January 2010 to June 2012 were also used to characterize the 

different reef treatments with respect to water elevation (fig. 10). The top of the reef was at or 

above the water level or above at the intertidal reefs 89 percent of the time and at the intertidalgap reefs for 84 percent of the time. For the subtidal 2 reefs, the top of the reef was at the water 

level or above for 22 percent of the time and at the subtidal reefs for 9 percent of the time. 

Table 3. Range of water quality parameters measured at reef and reference sites at Vermilion Cove, 

Louisiana, across all dates and construction statuses. Southwest Pass, La., was only sampled in spring 

and summer months. 

[Temp, temperature in degrees Celsius; DO, dissolved oxygen in milligrams per liter; Water clarity, secchi depth in 

centimeters; TSS, total suspended sediments in milligrams per liter; Chl. a, chlorophyll a in micrograms per liter] 

 Vermilion Cove Southwest Pass 

Temp (°C) 14.6-33.5 24.3-30.9 

DO (mg L-1) 0.3-9.2 5.2-7.8 

Water clarity (cm) 6.0-67.0 17.0-62.0 

Salinity 1.2-24.7 1.1-16.0 

TSS (mg L-1) 5.3-593.3 29.3-195.3 

Chl. a (μg L-1) 0.8-37.3 5.3-16.9 
24 

Figure 9. Overall mean salinity of all study sites at Vermilion Cove and Southwest Pass, Louisiana, plotted with salinity data 

continuous data recorder maintained by the State of Louisiana (CRMS 5041; LOCPR, 2012). Standard errors were all lesshown on the graph.
25 

Figure 10. Daily mean water levels at Vermilion Cove, Louisiana (CRMS0541; LOCPR, 2012), from January 2010 to June 2

referenced to NAVD 88 (feet [ft]). 
26 

Habitat Enhancement 

Because of unequal sample efforts, differences in construction dates spanning more than 

2 years, and differences in timing of samples particularly for preconstruction samples, we present 

the nekton abundance and species richness data below and describe it qualitatively. Comparison 

of matching sample dates was considered, but because of the 2-year difference in reef age, and 

the continued construction in the vicinity, we felt that it was difficult to interpret any patterns 

that may emerge. Tables of species present only postconstruction samples for comparison. 

A total of 60 gill net samples were collected over nine sampling periods in 2010 through 

2012 in Vermilion Cove. In total, 163 individuals, consisting of 18 species of fish and 

invertebrates, were collected. CPUE ranged from 0.6 ± 0.6 to 4.5 ± 1.7 individuals per gill net 

hour fished, and species richness ranged from 0.3 ± 0.3 to 2.3 ± 0.6 (fig. 11). Because of 

differences in construction dates and in order to standardize species comparisons among 

treatments, table 4 includes just the postconstruction data for all reference and reef sites. In 

postconstruction samples, a total of 131 individuals were collected. The most abundant 

organisms were bull shark (Carcharhinus leucas) and hardhead catfish (Ariopsis felis), which 

composed 54 percent of the postconstruction samples. 
27 

Figure 11. Mean catch per unit effort (CPUE) and number of species caught with gill nets, seine, and cast nets at reference, 

intertidal, and intertidal-gap reefs at Vermilion Cove, Louisiana. Bars represent standard error. Preconstruction samples 

and intertidal-gap samples were collected in spring 2010. Reference samples collected from fall 2010 through fall 2012. 

installation data were collected for subtidal 2 reefs. Note different axis scales for CPUE by gear type. 
28 

Table 4. Mean catch per unit effort (standard error) for gill net (per hour) at reference and reef sites at Vermilion Cove, Louis

the overall number of individuals. All data are postconstruction as indicated in table 1. Data represent uneven efforts and treatments (subtidal and intertidal: 9 sample events X 2 replicates X 2 gill net sets = 36 gill net samples collected in 2011 gap: 8 sample events X 2 replicates X 2 gill net sets = 32 gill net samples collected in 2011 and 2012; subtidal 2 = 2 eve

nets = 8 gill net samples collected in 2012). 

Species Common name Total Reference Subtidal Subtidal 2 Intert

Carcharhinus leucas Bull shark 38 1.7 (0.3) 2.3 (0.5) 1.0 (0.0) 2.8 (0Ariopsis felis Hardhead catfish 33 1.6 (0.4) 1.4 (0.4) 1.0 (0.0) 2.2 (1Callinectes sapidus Blue crab 8 1.0 (0.0) 1.0 (0.0) 0 (0.0) 1.7 (0Micropogonias undulates Atlantic croaker 8 0 (0.0) 1.0 (0.0) 2.0 (0.0) 1.0 (0Pogonias cromis Black drum 7 1.0 (0.0) 1.0 (0.0) 0 (0.0) 1.5 (0Paralichthys lethostigma Southern flounder 7 0 (0.0) 0 (0.0) 0 (0.0) 6.0 (0Dorosoma cepedianum Gizzard shad 6 0 (0.0) 1.0 (0.0) 0 (0.0) 1.0 (0Brevoortia patronus Gulf menhaden 5 2.0 (0.0) 0 (0.0) 0 (0.0) 1.5 (0Sciaenops ocellatus Red drum 4 1.0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0Cynoscion nebulosus Spotted seatrout 4 0 (0.0) 1.0 (0.0) 0 (0.0) 1.5 (0Mugil cephalus Striped mullet 3 0 (0.0) 0 (0.0) 0 (0.0) 3.0 (0Bagre marinus Gaftopsail catfish 2 1.0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0Alosa chrysochloris Skipjack herring 1 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0Archosargus probatocephalus Sheepshead 1 0 (0.0) 0 (0.0) 0 (0.0) 0 (0Bairdiella chrysoura Silver perch 1 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0Dasyatis americana Southern stingray 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0Atractosteus spatula Alligator gar 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0Dorosoma petenense Threadfin shad 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0

Total 131 2.4 (0.6) 2.2 (0.6) 2.0 (1.0) 4.5 (1
29 

A total of 113 seine samples were collected over eight sampling periods. In total, 6,263 

individuals, consisting of 33 species of fish and invertebrates were collected by using the seine. 

CPUE ranged from 33.3 ± 24.6 to 62.9 ± 21.6, whereas species richness ranged from 2.0 ± 0.7 to 

5.6 ± 0.7 (fig. 11). For postconstruction data, 28 species (5,563 individuals) were collected 

across reference and reef sites (table 5). The most abundant organisms postconstruction were bay 

anchovy (Anchoa mitchilli), grass shrimp (Palaeomonetes pugio), and white shrimp (Litopenaeus 

setiferus), accounting for 89.2 percent of the postconstruction catch by abundance. 
30 

Table 5. Mean catch per unit effort (standard error) for seine (per 10-meter seine) at reference and reef sites at Vermilion Cove, Lou

overall number of individuals. All data are postconstruction as indicated in tables 1 and 3. Data represent uneven efforts and yeaand intertidal: 9 sample events X 2 replicates X 2 seine pulls = 36 seine samples collected in 2011 and 2012; intertidal gap: 8 sam

seine pulls = 32 seine samples collected in 2011 and 2012; subtidal 2 = 2 events x 2 replicates x 2 seine pulls = 8 seine samples 

Species Common name Total Reference Subtidal Subtidal 2 Intertidal Anchoa mitchilli Bay anchovy 4,182 60.7 (18.1) 52.9 (13.9) 57.0 (47.0) 50.3 (25.2) Palaemonetes pugio Grass shrimp 465 7.7 (2.2) 7.8 (2.3) 1.0 (0.0) 15.3 (6.2) Litopenaeus setiferus White shrimp 316 6.0 (2.1) 8.7 (3.7) 7.0 (0.0) 7.8 (2.8) Mugil cephalus Striped mullet 153 1.2 (0.2) 3.9 (2.3) 0 (0.0) 21.3 (14.3) Brevoortia patronus Gulf menhaden 143 5.0 (1.0) 4.4 (2.3) 0 (0.0) 9.8 (2.8) Membras martinica Rough silverside 143 3.0 (0.0) 37.0 (10.0) 2.0 (0.0) 9.7 (8.7) Farfantepenaeus aztecus Brown shrimp 29 0 (0.0) 2.5 (1.0) 0 (0.0) 1.6 (0.4) Callinectes sapidus Blue crab 26 1.0 (0.0) 1.0 (0.0) 0 (0.0) 1.6 (0.4) Bairdiella chrysoura Silver perch 24 0 (0.0) 2.2 (0.7) 0 (0.0) 1.7 (0.7) Cynoscion arenarius Sandtrout 23 1.0 (0.0) 3.0 (1.4) 1.0 (0.0) 1.7 (0.7) Oligoplites saurus Leatherjack 18 1.0 (0.0) 1.5 (0.5) 1.0 (0.0) 1.3 (0.3) Micropogonas undulatus Atlantic croaker 9 2.0 (0.0) 2.0 (0.0) 0 (0.0) 1.3 (0.3) Elops saurus Ladyfish 7 2.0 (0.6) 1.0 (0.0) 0 (0.0) 0 (0.0) Anchoa hepsetus Striped anchovy 4 1.0 (0.0) 2.0 (0.0) 0 (0.0) 0 (0.0) Menida beryllina Inland silverside 3 0 (0.0) 1.0 (0.0) 0 (0.0) 1.0 (0.0) Dorosoma cepedianum Gizzard shad 3 0 (0.0) 3.0 (0.0) 0 (0.0) 0 (0.0) Gobionellus boleosoma Darter goby 3 0 (0.0) 2.0 (0.0) 0 (0.0) 1.0 (0.0) Bagre marinus Gaftopsail catfish 2 0 (0.0) 1.0 (0.0) 0 (0.0) 1.0 (0.0) Alosa chrysochloris Skipjack herring 1 1.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Fundulus jenkinsi Saltmarsh minnow 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Fundulus grandis Gulf killifish 1 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0.0) Gobiosoma bosc Naked goby 1 1.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Lagodon rhomboides Pinfish 1 1.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Dorosoma petenense Threadfin shad 1 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Caranx sp. unk. Jack 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Paralichthys lethostigma Southern flounder 1 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0.0) Strongylura marina Atlantic needlefish 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Micropanope sculptipes Sculpted mud crab 1 1.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 

Total 5,563 46.8 (13.4) 59.2 (13.8) 33.3 (24.6) 62.9 (21.6) 
31 

A total of 330 cast net samples were collected over 9 sampling periods. In total, 2,167 

individuals, consisting of 29 species of fish and invertebrates were collected. CPUE ranged from 

2.8 ± 0.7 to 12.9 ± 7.7, whereas species richness ranged from 0.8 ± 0.3 to 2.1 ±0.2 (fig. 11). Of 

the postconstruction data, 1,760 individuals consisting of 25 species were collected (table 6). The 

most abundant organisms were Gulf menhaden (Brevoortia patronus), bay anchovy, and white 

shrimp, accounting for 73.4 percent of the postconstruction catch by abundance. 
32 

Table 6. Mean catch per unit effort (standard error) for cast net throw at reference and reef sites at Vermilion Cove, Louisiana. “Tota

individuals. All data are postconstruction as indicated in table 1. Data represent uneven efforts and years across treatments (subevents X 2 replicates X 5 cast net throws = 90 cast net samples collected in 2011 and 2012; intertidal gap: 8 sample events X 2 r80 cast net samples collected in 2011 and 2012; subtidal 2 = 2 events X 2 replicates X 5 cast net throws = 20 cast net samples c

Species Common name Total Reference Subtidal Subtidal 2 Intertid

Brevoortia patronus Gulf menhaden 940 2.7 (0.7) 7.5 (2.7) 15.0 (0.0) 67.6 (45Anchoa mitchilli Bay anchovy 219 2.4 (0.5) 3.6 (1.0) 7.0 (6.0) 1.9 (0.5Litopenaeus setiferus White shrimp 132 2.8 (0.7) 2.6 (0.4) 1.0 (0.0) 2.1 (0.4Mugil cephalus Striped mullet 116 2.0 (0.8) 1.4 (0.2) 1.0 (0.0) 3.5 (0.9Membras martinica Rough silverside 114 4.0 (1.5) 4.2 (1.4) 8.0 (7.0) 2.3 (1.0Palaemonetes pugio Grass shrimp 94 4.4 (1.7) 3.2 (0.9) 0 (0.0) 2.0 (1.0Farfantepenaeus aztecus Brown shrimp 85 1.1 (0.1) 1.0 (0.0) 0 (0.0) 1.2 (0.2Micropogonias undulatus Atlantic croaker 15 1.5 (0.5) 1.2 (0.2) 1.0 (0.0) 1.0 (0.0Cynoscion arenarius Sandtrout 11 1.0 (0.0) 1.3 (0.3) 0 (0.0) 1.0 (0.0Ariopsis felis Hardhead catfish 5 0 (0.0) 1.0 (0.0) 0 (0.0) 1.0 (0.0Menidia beryllina Inland silverside 4 0 (0.0) 2.0 (0.0) 0 (0.0) 2.0 (0.0Bagre marinus Gaftopsail catfish 3 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0.0Bairdiella chrysoura Silver perch 3 1.0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Dorosoma cepedianum Gizzard shad 3 0 (0.0) 3.0 (0.0) 0 (0.0) 0 (0.0) Scianidae unk. croaker/drum 2 1.0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Callinectes sapidus Blue crab 2 1.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Lagodon rhomboides Pinfish 2 1.0 (0.0) 0 (0.0) 1.0 (0.0) 0 (0.0) Leiostomus xanthurus Spot 2 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0.0Anchoa hepsetus Striped anchovy 2 2.0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) Eurypanopeus depressus Depressed mud crab 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Strongylura marina Atlantic needlefish 1 0 (0.0) 0 (0.0) 1.0 (0.0) 0 (0.0) Cynoscion nebulosus Spotted seatrout 1 0 (0.0) 0 (0.0) 0 (0.0) 1.0 (0.0Paralichthys lethostigma Southern flounder 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Oligoplites saurus Leatherjack 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) Cynoscion nothus Silver seatrout 1 0 (0.0) 1.0 (0.0) 0 (0.0) 0 (0.0) 

Total 1,760 3.3 (0.6) 4.1 (0.7) 6.9 (4.1) 12.9 (7.
33 

A total of 48 substrate trays were deployed in Vermilion Cove during 2011 and 2012; 

however, only 41 were recovered and counted. In total, 2,928 individuals were identified (table 

7). The most abundant organisms overall were grass shrimp (P. pugio), Harris mud crab 

(Rhithropanopeus harrisii), blue crab (Callinectes sapidus), and naked goby (Gobiosoma bosc), 

accounting for 97.1 percent of the total catch. Trays at reference sites had a mean catch of 27.3 ± 

12.7 individuals m-2, whereas trays at reef sites had a mean catch of 13.2 ± 2.9 individuals m-2. 

Seven species were unique to reef trays and included two known reef residents (darter goby, 

feathered blenny) and several mud crabs which are known to aggregate around reefs. 

Table 7. Density (standard error) of species collected on substrate trays deployed near reference, 

subtidal, intertidal, and intertidal‐gap sites at Vermilion Cove, Louisiana. “Total” indicates the overall 

number of individuals. Trays were deployed for 2‐3 weeks in late summer of both 2011 and 2012. 

 Mean individuals m-2

Species Common name Total Overall Reef Reference 

Palaemonetes pugio Grass shrimp 1,723 261.1 (54.3) 158.4 (29.7) 774.5 (151.1) 

Rhithropanopeus harrisii Harris mud crab 494 77.4 (24.4) 84.0 (28.1) 36.4 (7.2) 

Callinectes sapidus Blue crab 455 64.6 (7.4) 69.7 (8.4) 37.3 (6.3) 

Gobiosoma bosc Naked goby 171 28.8 (7.7) 32.4 (9.3) 12.7 (3.3) 

Gobiosox strumosus Skilletfish 43 10.3 (2.2) 10.6 (2.4) 4.5 (0.0) 

Gobionellus boleosoma Darter goby 14 9.1 (3.0) 9.1 (3.0) 0.0 

Alpheus sp. Snapping shrimp 6 5.5 (0.9) 5.5 (0.9) 0.0 

Eurypanopeus depressus Depressed mud crab 5 5.7 (1.1) 5.7 (1.1) 0.0 

Farfantepenaeus aztecus Brown shrimp 4 18.2 (0.0) 18.2 (0.0) 0.0 

Litopenaeus setiferus White shrimp 3 6.8 (2.3) 6.8 (2.3) 0.0 

Panopeus simpsoni Oystershell mud crab 3 6.8 (2.3) 6.8 (2.3) 0.0 

Hypsoblennius hentzi Feathered blenny 2 4.5 (0.0) 4.5 0.0) 4.5 (0.0) 

Menippe adina Gulf stone crab 2 9.1 (0.0) 9.1 (0.0) 0.0 

Myrophis punctatus Speckled worm-eel 2 4.5 (0.0) 4.5 (0.0) 4.5 (0.0) 

Clibanarisu vittatus Thinstripe hermit crab 1 4.5 (0.0) 4.5 (0.0) 4.5 (0.0) 

 Total 2,928 15.8 (3.3) 13.2 (2.9) 27.3 (12.7) 

Mean density of species collected in trays was much lower than two recent projects that 

used the same gear type (Lake Fortuna: 448.3 ± 63.8 individuals m-2; Grand Isle: 332.9 ± 35.4 

individuals m-2; La Peyre, unpub. data). Vermilion Cove is lower salinity than these sites which 

may explain some of the difference. Other published information on benthic communities is not 

as directly comparable because of slight differences in gear use, including the lack of an 

enclosure net. For example, Plunket and LaPeyre (2005) used open trays to sample harvested 

oyster leases in Barataria Bay, La., and reported lower densities of fish (13.9 individuals m-2) and 

invertebrates (168.4 individuals m-2). Other tray studies (Tolley and Volety, 2005), and drop 

sampling studies (Shervette and Gelwick, 2008; Stunz and others, 2010) on other oyster reefs in 

the northern Gulf of Mexico also reported densities more similar to those found in the present 

study. 
34 

Southwest Pass 

Shoreline Stabilization 

Mean shoreline retreat at Southwest Pass sites from August 2011 to July 2012, was 26.7 

± 2.9 cm mo-1. This rate presents retreat for the year preconstruction. These data will provide a 

baseline measure and marker for continued collection of shoreline movement data at these sites. 

 Mean soil percentage of organic matter was 11.8 ± 0.4 percent across all sample dates 

and sites (preconstruction and postconstruction combined). Mean percentage of vegetative cover 

across all sample dates and treatments at Southwest Pass was 31.3 ± 4.2 percent. The most 

abundant species were inland saltgrass (Distichlis spicata) and Juncus roemerianus. Other 

species present included Scirpus robusta, Spartina alterniflora, Phragmites australis, Borrichia 

frutescens, and Batis maritima. Mean live aboveground vegetative biomass was 584.6 ± 8.7 g m -2

 (fig. 12). There were no significant differences between treatment or sample date for soil 

percent organic matter, percent vegetative cover, or aboveground biomass. Mean belowground 

vegetative biomass differed between preconstruction and postconstruction samples with higher 

biomass preconstruction (304.3 ± 57.3 g m-2) as compared to postconstruction (160.2 ± 18.8 g m -2

 ) (p=0.007). Postconstruction samples were taken shortly after completion of construction (fig. 

12). 
35 

Figure 12. Mean aboveground and belowground vegetative biomass (grams per square meter [g m-2]) of 

reference and treatments at Southwest Pass, Louisiana, sites. Bars represent standard error. 

Preconstruction samples were collected in August 2011; postconstruction samples were collected in 

July 2012 after the June 2012 construction. 
36 

Reef Sustainability 

Because of construction ending in June 2012, there was insufficient time to allow for 

recruitment (attachment plus survival) on the reefs. Further sampling over a longer time period 

would be necessary to determine if these sites are conducive to oyster recruitment and growth. 

Environmental Variables 

Water quality parameters are reported as ranges across all dates and treatment types 

(table 3). Because only summer samples were collected for this study area, ranges reported do 

not likely reflect the range occurring throughout the year. No differences by site were expected 

or recorded. Daily mean water levels from the continuous data recorder at a nearby CRMS sites 

(CRMS 0541) show that subtidal 2 reefs are exposed for 2 percent of the time, and subtidal reefs 

are exposed for less than 1 percent of the time (fig. 13).
37 

Figure 13. Daily mean water levels at Southwest Pass, Louisiana (CRMS0541; LOCPR, 2012), from January 2010 to June 2

referenced to NAVD 88 (feet). 
38 

Habitat Enhancement 

No preconstruction nekton data were collected at Southwest Pass. A total of 12 gill net 

samples were collected over 2 sampling periods postconstruction (June, July 2012). Overall, 46 

individuals from seven species were caught (table 8). Hardhead catfish (A. felis) were the most 

abundant organism, accounting for 76.1 percent of the total catch. There were no statistically 

significant differences in CPUE or species richness between treatment and reference sites (fig. 

14). 

Table 8. Mean catch per unit effort for gill net (per hour) at reference and reef sites at Southwest Pass, 

Louisiana, sites. “Total” indicates the overall number of individuals. All data are postconstruction as 

indicated in table 2. Data represent two summer 2012 sample events (2 events X 2 replicates X 2 gill 

net sets = 8 sets per treatment). 

Species Common name Total Reference Subtidal Subtidal 2 

Ariopsis felis Hardhead catfish 35 4.3 (0.9) 3.3 (1.9) 4.0 (1.2) 

Carcharhinus leucas Bull shark 5 1.0 (0.0) 1.0 (0.0) 1.5 (0.5) 

Bagre marinus Gaftopsail catfish 2 1.0 (0.0) 0 (0.0) 1.0 (0.0) 

Callinectes sapidus Blue crab 1 0 (0.0) 1.0 (0.0) 0 (0.0) 

Micropogonias undulates Atlantic croaker 1 0 (0.0) 1.0 (0.0) 0 (0.0) 

Cynoscion nebulosus Spotted seatrout 1 0 (0.0) 0 (0.0) 1.0 (0.0) 

Peprilus alepidotus Harvestfish 1 1.0 (0.0) 0 (0.0) 0 (0.0) 

 Total 46 4.0 (1.4) 3.3 (1.7) 4.3 (1.5) 
39 

Figure 14. Mean catch per unit effort (CPUE) and number of species caught with gill nets, seines, and cast-nets at reference

2 sites at Southwest Pass, Louisiana. Bars represent standard error. All data are postconstruction. Note different axes sc
40 

Overall, 24 seine samples were collected over two sample dates postconstruction at 

Southwest Pass. In total, 1,462 individuals consisting of 14 species were caught (table 9). The 

most abundant species was bay anchovy (A. michilli), which accounted for 83.7 percent of the 

overall catch. Other dominant species included white shrimp (L. setiferus) and Gulf menhaden 

(B. patronus).There were no statistically significant differences in CPUE or number of species 

caught between treatments (fig. 14). 

Table 9. Mean catch per unit for seine (10-meter seine) at reference and reef sites at Southwest Pass, 

Louisiana. “Total” indicates the overall number of individuals. All data are postconstruction as indicated 

in tables 2 and 3. Data represent two summer 2012 sample events (2 events X 2 replicates X 2 seine 

pulls = 8 seine pulls per treatment). 

Species Common name Total Reference Subtidal Subtidal 2 

Anchoa mitchilli Bay anchovy 1,224 43.7 (15.7) 41.3 (12.1) 73.5 (41.9) 

Litopenaeus setiferus White shrimp 76 3.8 (1.7) 4.3 (1.1) 15.5 (0.5) 

Brevoortia patronus Gulf menhaden 53 1.0 (0.0) 18.5 (16.5) 7.5 (6.5) 

Farfantepenaeus aztecus Brown shrimp 39 1.7 (0.7) 2.5 (0.7) 3.8 (1.0) 

Palaemonetes pugio Grass shrimp 34 2.5 (0.5) 3.0 (1.2) 3.4 (1.0) 

Micropogonias undulatus Atlantic croaker 8 2.0 (0.0) 2.0 (1.0) 1.0 (0.0) 

Bairdiella chrysoura Silver perch 7 0 (0.0) 1.0 (0.0) 1.7 (0.7) 

Anchoa hepsetus Striped anchovy 6 1.0 (0.0) 4.0 (0.0) 1.0 (0.0) 

Callinectes sapidus Blue crab 5 1.0 (0.0) 1.0 (0.0) 2.0 (0.0) 

Membras martinica Rough silverside 4 0 (0.0) 0 (0.0) 2.0 (1.0) 

Cynoscion arenarius Sandtrout 2 1.0 (0.0) 1.0 (0.0) 0 (0.0) 

Cynoscion nebulosus Spotted seatrout 2 2.0 (0.0) 0 (0.0) 0 (0.0) 

Gobiosoma bosc Naked goby 1 0 (0.0) 0 (0.0) 1.0 (0.0) 

Synodus foetens Inshore lizzardfish 1 1.0 (0.0) 0 (0.0) 0 (0.0) 

 Total 1,462 42.6 (14.7) 54.5 (12.0) 85.6 (41.0) 

A total of 60 cast net samples, collected over 2 sampling periods postconstruction, were 

collected at Southwest Pass, Louisiana. Overall, 140 individuals consisting of 12 species were 

caught (table 10). The most abundant species were bay anchovy (A. mitchilli) and brown shrimp 

(Farfantepenaeus aztecus), which accounted for 76.4 percent of the overall catch. There were no 

statistically significant differences in CPUE or species richness between treatments (fig. 14). 
41 

Table 10. Mean catch per unit effort for cast net throws at reference and reef sites at Southwest Pass, 

Louisiana. “Total” indicates the overall number of individuals. All data are postconstruction as indicated 

in tables 2 and 3. Data represent two summer 2012 sample events (2 events X 2 replicates X 5 cast 

net throws = 20 cast net throws per treatment). 

Species Common name Total Reference Subtidal Subtidal 2 

Anchoa mitchilli Bay anchovy 93 9.0 (5.1) 4.4 (1.2) 5.8 (2.6) 

Farfantepenaeus aztecus Brown shrimp 14 1.5 (0.3) 1.0 (0.0) 1.0 (0.0) 

Brevoortia patronus Gulf menhaden 11 0 (0.0) 0 (0.0) 11.0 (0.0) 

Membras martinica Rough silverside 7 1.0 (0.0) 2.0 (0.0) 1.0 (0.0) 

Micropogonias undulates Atlantic croaker 5 0 (0.0) 1.3 (0.3) 1.0 (0.0) 

Ariopsis felis Hardhead catfish 3 0 (0.0) 1.0 (0.0) 1.0 (0.0) 

Trachinotus carolinus Pompano 2 1.0 (0.0) 1.0 (0.0) 0 (0.0) 

Palaemonetes pugio Grass shrimp 1 0 (0.0) 0 (0.0) 1.0 (0.0) 

Mugil cephalus Striped mullet 1 1.0 (0.0) 0 (0.0) 0 (0.0) 

Callinectes sapidus Blue crab 1 0 (0.0) 0 (0.0) 1.0 (0.0) 

Bairdiella chrysoura Silver perch 1 1.0 (0.0) 0 (0.0) 0 (0.0) 

Strongylura marina Atlantic needlefish 1 1.0 (0.0) 0 (0.0) 0 (0.0) 

 Total 140 1.9 (1.1) 2.3 (0.7) 2.8 (1.1) 

Summary and Conclusions 

Because the original project called for comparison of subtidal and intertidal reef 

development and performance, the range of reef “ages” (from 1 to 30 months [mo]), combined 

with continued construction activities in the vicinity of the project, make any interpretation of the 

data, or reef development trajectories difficult at this stage. This project did successfully collect 

extensive detailed data on shoreline position and movement, on-reef oyster recruitment and 

survival, adjacent marsh vigor, and nekton communities by using the experimental reef areas 

from 2010 to 2012, thus providing a valuable baseline of data for future evaluations. 

Through 2010 and 2011 there was no development of a surviving oyster reef community 

on reefs at Vermilion Cove. As of July 2012, oysters recruited in fall 2011 were thriving, 

suggesting that perhaps this last year provided conditions for the development of a small reef 

community; however, it is difficult to interpret much from these data. During 2010 and 2011, 

confounding factors of continued construction activities very near established reefs, unidentified 

potential impacts of the Deepwater Horizon oil spill (2010), or low water impacts from the 100-

year floods in 2011 all may have contributed to our lack of viable oyster recruitment. 

Alternatively, because this area chosen for the creation of the reefs is well known to regularly 

experience low salinity caused by influence of the Atchafalaya River, and subsequently low 

growth and survival of oysters such that most oyster leases in the area are only productive 

approximately every 10 years, it is equally likely that the provision of the reef substrate must be 

timed with a successful year for oyster recruitment and survival before the reefs will become 

established. 
42 

Reefs created at Southwest Pass have only been constructed within the last 6 mo of the 

study, and no recruitment has been noted on the reefs. Southwest Pass is located along a busy 

navigation channel and is an area with rapid water movement and a relatively steep incline. The 

sediments in this area are more clay, and there is little shell and hard bottom as is found in 

Vermilion Cove. 

Although recruitment is occurring on the Vermilion Cove reefs, the local environment is 

not conducive every year to survival and development of the reef; given more years of 

monitoring, it is quite possible that over time, as appears to happen on the adjacent public seed 

grounds, conditions may occur which will support good recruitment, survival, and growth of an 

oyster set. This reef project highlights the need to examine these reef creation projects over the 

long term to truly identify sustainable reef trajectories; with highly variable salinity regimes in 

many areas of coastal Louisiana, success or failure may not be determined within a short time 

frame. For restoration in which immediate reef development is needed, an area known to have 

only an occasional “good” year for recruitment may not be most conducive to such restoration. 

Similarly, it is not clear with our current knowledge of oyster biology if Southwest Pass water 

conditions are conducive to spat recruitment and survival. Further investigation into 

hydrodynamics of the area and water velocity limits for spat and oysters would provide needed 

insight. 

Because many of the processes identified for monitoring reflect long-term processes, and 

we were interested initially in comparing the development trajectories of subtidal versus 

intertidal reefs, future work would be extremely interesting in understanding (1) if there are 

differences in the development of thriving oyster communities between subtidal and intertidal 

reefs, based on food availability, exposure and potential predation risks; (2) if subtidal reefs 

which develop a thriving oyster population will build upwards to resemble the intertidal reefs 

over time or will develop differently; (3) if subtidal reefs become intertidal reefs, will they then 

act on shoreline movement in the same way as the artificial intertidal reefs; (4) at what point, or 

what density and size of oysters, would a measurable water quality effect exist; and (5) do 

subtidal and intertidal reefs provide different nekton enhancement as measured by community 

composition, species richness, and abundances? 

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