Marine Sanctuaries Conservation Series ONMS-10-06

U.S. Department of Commerce 

National Oceanic and Atmospheric Administration 

National Ocean Service 

Office of Ocean and Coastal Resource Management 

Office of National Marine Sanctuaries November 2010 

N-Control 

Seagrass Restoration Monitoring Report 

Monitoring Events 2003-2008 

Florida Keys National Marine Sanctuary 

Monroe County, Florida 
About the Marine Sanctuaries Conservation Series 

The National Oceanic and Atmospheric Administration’s National Ocean Service (NOS) 

administers the Office of National Marine Sanctuaries (ONMS). Its mission is to identify, 

designate, protect and manage the ecological, recreational, research, educational, 

historical, and aesthetic resources and qualities of nationally significant coastal and 

marine areas. The existing marine sanctuaries differ widely in their natural and 

historical resources and include nearshore and open ocean areas ranging in size from 

less than one to over 5,000 square miles. Protected habitats include rocky coasts, kelp 

forests, coral reefs, sea grass beds, estuarine habitats, hard and soft bottom habitats, 

segments of whale migration routes, and shipwrecks. 

Because of considerable differences in settings, resources, and threats, each marine 

sanctuary has a tailored management plan. Conservation, education, research, 

monitoring and enforcement programs vary accordingly. The integration of these 

programs is fundamental to marine protected area management. The Marine 

Sanctuaries Conservation Series reflects and supports this integration by providing a 

forum for publication and discussion of the complex issues currently facing the sanctuary 

system. Topics of published reports vary substantially and may include descriptions of 

educational programs, discussions on resource management issues, and results of 

scientific research and monitoring projects. The series facilitates integration of natural 

sciences, socioeconomic and cultural sciences, education, and policy development to 

accomplish the diverse needs of NOAA’s resource protection mandate. 
N-Control 

Seagrass Restoration Monitoring Report 

Monitoring Events 2003-2008 

Florida Keys National Marine Sanctuary 

Monroe County, Florida 

A. A. Farrer 

Florida Keys National Marine Sanctuary, 33 East Quay Road, Key West, FL 33040 

Silver Spring, Maryland 

November 2010 

U.S. Department of Commerce 

Gary Locke, Secretary 

National Ocean and Atmospheric Administration 

Jane Lubchenco, Ph.D. 

Under Secretary of Commerce for Oceans and Atmosphere 

National Ocean Service 

David Kennedy, Acting Assistant Administrator 

Office of National Marine Sanctuaries 

Daniel J. Basta, Director
DISCLAIMER 

Report content does not necessarily reflect the views and policies of the Office of 

National Marine Sanctuaries or the National Oceanic and Atmospheric Administration, 

nor does the mention of trade names or commercial products constitute endorsement or 

recommendation for use. 

REPORT AVAILABILITY 

Electronic copies of this report may be downloaded from the Office of National Marine 

Sanctuaries web site at http://sanctuaries.noaa.gov. Hard copies may be available from 

the following address: 

 National Oceanic and Atmospheric Administration

 Office of National Marine Sanctuaries

 SSMC4, N/ORM62 

 1305 East-West Highway 

 Silver Spring, MD 20910 

COVER 

Clockwise: 

Bird stakes at the N-Control restoration site. (Credit: NOAA) 

The vessel N-Control aground on Knight Key bank. (Credit: NOAA) 

Injury to the seagrass bed from the N-Control vessel. (Credit: NOAA) 

Damage to Turtle grass (Thalassia testudinum) at the N-Control vessel grounding site. 

(Credit: NOAA) 

SUGGESTED CITATION

Farrer, A. A. 2010. N-Control Seagrass Restoration Monitoring Report, Monitoring 

Events 2003-2008. Florida Keys National Marine Sanctuary, Monroe County, Florida. 

Marine Sanctuaries Conservation Series ONMS-10-06. U.S. Department of Commerce, 

National Oceanic and Atmospheric Administration, Office of National Marine 

Sanctuaries, Silver Spring, MD. 32 pp. 

CONTACT 

Alicia A. Farrer, Environmental Specialist II 

Florida Keys National Marine Sanctuary, 33 East Quay Road, Key West, FL 33040 

Email: alicia.farrer@noaa.gov
i 

ABSTRACT 

This document presents the results of the monitoring of a repaired seagrass area injured 

by the N-Control vessel grounding incident of May 29, 2001. This grounding occurred in 

State of Florida waters within the boundaries of the Florida Keys National Marine 

Sanctuary (FKNMS) and impacted a total of 96.87 m2

 of seagrass habitat, predominantly 

Turtle grass (Thalassia testudinum). Restoration of this site was completed on March 25, 

2003 and consisted of forty-four seagrass planting units (Halodule wrightii and 

Syringodium filiforme) and 39 bird stakes. The monitoring program of the N-Control site 

was designed to determine whether the restoration effort provided services in a manner 

consistent with restoration goals, and to monitor the potential need for mid-course 

corrections. Monitoring consisted of both quantitative and qualitative methods adapted 

from Fonseca et al “Guidelines for the Conservation and Restoration of Seagrasses in the 

United States and Adjacent Waters”. A total of six monitoring events were conducted 

over five and a half years. After 64 months (5.5 years) post-restoration, the percent cover 

of total seagrass in the restored injury increased from 5.6% to 17%. The target species, T. 

testudinum, increased from 0.5% to 12.1% in the restoration area by the 5.5 year 

monitoring event. In comparison, the percent cover of T. testudinum was 28.5% in the 

reference area adjacent to the injury during the 5.5 year monitoring event. This 

restoration effort accelerated the recovery of the injured area but the injury has yet to 

reach pre-grounding baseline levels. Research on restoration techniques and natural 

recovery continues, and will provide valuable information on the practicality and 

effectiveness of seagrass restoration of vessel grounding injuries. 

KEY WORDS 

N-Control, Florida Keys National Marine Sanctuary, seagrass, vessel grounding, 

restoration, monitoring, planting units, bird stakes

 
ii 

TABLE OF CONTENTS 

Topic Page

Abstract ................................................................................................................................ i 

Key Words ........................................................................................................................... i 

Table Of Contents ............................................................................................................... ii 

Introduction ......................................................................................................................... 1 

Background ..................................................................................................................... 2 

Damage Assessment ....................................................................................................... 3 

Seagrass Restoration ....................................................................................................... 6 

Restoration Monitoring ................................................................................................... 9 

Methods............................................................................................................................. 10 

Field Methods ............................................................................................................... 10 

Statistical Analysis ........................................................................................................ 11 

Model Recovery Estimates ........................................................................................... 11 

Calculated Recovery Estimates ..................................................................................... 11 

Results ............................................................................................................................... 12 

0.5 Year Monitoring Event (September 29, 2003) ....................................................... 12 

1.0 Year Monitoring Event (April 26, 2004) ................................................................ 13 

1.5 Year Monitoring Event (October 21, 2004) ............................................................ 13 

3.0 Year Monitoring Event (April 17, 2006) ................................................................ 13 

3.5 Year Monitoring Event (September 27, 2006) ....................................................... 14 

5.5 Year Monitoring Event (August 07, 2008) ............................................................. 15 

Summary Of Aerial Coverage (Bb) Data ...................................................................... 16 

Statistical Analysis ........................................................................................................ 17 

Model Recovery Estimates ........................................................................................... 18 

Discussion ......................................................................................................................... 20

Acknowledgements ........................................................................................................... 23

Literature Cited ................................................................................................................. 24 

Appendix A: Photo Documentation Of The N-Control Vessel Grounding, Injury Site 

And Restoration Area. ...................................................................................................... 28

Appendix B: Braun-Blanquet (Bb) Cover-Abundance Scale With Range Mid-Point 

Values ............................................................................................................................... 30 

 
iii 

LIST OF TABLES AND FIGURES 

Table Number and Title Page

Table 1. Monitoring event timeline for the N-Control grounding restoration ................... 1

Table 2. Percent cover of seagrass species, total seagrass, macroalgae, and coral present 

at the N-Control grounding site on 06/05/2001.. ................................................................ 6

Table 3. Alternatives for seagrass restoration in the FKNMS ........................................... 7

Table 4. Categories and Timing of Monitoring ................................................................. 9

Table 5. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the NControl on 9/29/2003 ........................................................................................................ 12

Table 6. Mean shoot density of seagrass species at the N-Control on 9/29/2003 ........... 12

Table 7. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the NControl on 4/26/2004 ........................................................................................................ 13

Table 8. Mean shoot density of seagrass species at the N-Control on 4/26/2004 ........... 13

Table 9. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the NControl on 4/17/2006 ........................................................................................................ 14

Table 10. Mean shoot density of seagrass species at the N-Control on 4/17/2006 ......... 14

Table 11. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the 

N-Control on 9/27/2006 .................................................................................................... 15

Table 12. Mean shoot density of seagrass species at the N-Control restoration site on 

9/27/2006.. ........................................................................................................................ 15

Table 13. Percent cover of seagrass species, total seagrass, macroalgae and coral at the 

N-Control on 8/07/2008 .................................................................................................... 15

Table 14. Mean shoot density of seagrass species at the N-Control restoration site on 

8/07/2008.. ........................................................................................................................ 16

Table 15. Comparison of percent recovery between the restoration (RS) and reference 

(RF) areas for each species of seagrass, total seagrass, macroalgae, and coral over the 

course of six monitoring events. ....................................................................................... 16
iv 

Table 16. Model predicted percent recovery of T. testudinum at the N-Control restoration 

site. .................................................................................................................................... 19

Table 17. Model predicted percent recovery of H.wrightii/S.filiforme at the N-Control

restoration site. .................................................................................................................. 19

Table 18. Linear regression of the percent recovery of T. testudinum, S. filiforme and H. 

wrightii at the N-Control restoration site based on the density statistic Di. ...................... 19

Figure Number and Title Page

Figure 1. Location of the N-Control grounding injury at Knight Key Bank. .................... 4

Figure 2. Georeferenced map of the N-Control injury as surveyed 6/05/2001. ................ 5

Figure 3. Restoration activities conducted at the N-Control injury site on.3/25/2003 ...... 8

Figure 4. Scatter plot of Braun-Blanquet scores and Thalassia testudinum shoot counts 

from the 8/07/2008 monitoring event. .............................................................................. 18

Figure 5. Graphical depiction of the shoot density data from the 3, 3.5 and 5.5 year 

monitoring events.............................................................................................................. 21

Figure 6. Linear regression of the calculated percent recovery of T. testudinum over time 

post restoration. ................................................................................................................. 22
1 

INTRODUCTION 

This document presents the results of the monitoring of a repaired seagrass area injured by the NControl vessel grounding incident of May 29, 2001. This grounding occurred in State of Florida 

waters within the boundaries of the Florida Keys National Marine Sanctuary (FKNMS). The 

National Oceanic and Atmospheric Administration (NOAA) and the Board of Trustees of the 

Internal Improvement Trust Fund of the State of Florida, (“State of Florida” or “state”) are the 

co-trustees for the natural resources within the FKNMS and are responsible for mediating the 

restoration of the damaged marine resources and monitoring the outcome of the restoration 

action. The restoration monitoring program tracks patterns of biological recovery, determines the 

success of restoration measures, and assesses the resiliency to environmental and anthropogenic 

disturbances of the site over time. To evaluate restoration success, reference habitats adjacent to 

the restoration site are concurrently monitored to compare against the condition of restored 

seagrass areas. 

The monitoring program of the N-Control site was designed to determine whether the restoration 

effort provided services in a manner consistent with restoration goals, and to monitor the 

potential need for mid-course corrections. The monitoring program allowed for detection of, and 

response to, significant changes in seagrass recovery rates or damage to restoration components 

(e.g., bird stakes, seagrass transplants) as a result of external events, such as major storms or 

vandalism. The monitoring schedule was as follows: baseline (day 0), 0.5, 1.0, 1.5, 2.0, 2.5, 3.5 

and 4.5 years after restoration implementation. Restoration of this site was initiated on March 

25, 2003. The dates for each monitoring event are listed in Table 1. The planned 2.0 and 2.5 

year monitoring events were not completed due to staff availability and logistical difficulties. 

Table 1. Monitoring event timeline for the N-Control grounding restoration 

Event Date 

Vessel Grounding 05/29/2001 

Injury Assessment 06/05/2001 

Restoration 03/25/2003 

0.5 Year 09/29/2003 

1.0 Year 04/26/2004 

1.5 Year 10/21/2004 

3.0 Year 04/17/2006 

3.5 Year 09/27/2006 

4.5 Year 08/07/2008* 

 *referred to as 5.5 year event 
2 

Background 

Healthy seagrass communities serve an important ecological and socioeconomic function in the 

Florida Keys (FKNMS 1996). Seagrass beds are nurseries for numerous species of fish and 

invertebrates and many commercial fishery species rely on seagrass habitat during some part of 

their life cycle, including pink shrimp, lobster, snapper, and stone crab. Seagrass beds are 

effective storm surge buffers for the low-lying Keys, reducing property damage and coastal 

erosion during extreme weather events. Seagrasses also function as natural sediment filters that 

reduce water column turbidity. The natural filtration of water by seagrasses is a major 

contributor to the water clarity, a characteristic appreciated by those who live in or visit the 

Keysand is vital to other members of the living marine resources community, including coral 

reefs, which are vulnerable to suspended and dissolved substances in turbid water (Short and 

Short 1984). 

Seagrasses are vascular plants that produce flowers, fruits, and seeds. The predominant species 

of seagrass in the Florida Keys are Thalassia testudinum (Turtle grass), Syringodium filiforme

(Manatee grass), and Halodule wrightii (Cuban shoal grass). For these species, the horizontal 

rhizome and root system is underground, protecting much of the plant biomass from the 

elements. The root/rhizome system grows laterally, sending short shoots vertically, above the 

sediment surface. S. filiforme and H. wrightii disperse easily and can initiate growth rapidly in 

relatively unstable sediments, making them the principal seagrass colonizers in this region. T. 

testudinum dominates in most areas of the Florida Keys and maintains a robust root-rhizome 

system deep underneath the substrate. Of particular management concern are vessel grounding 

injuries to T. testudinum because it has the lowest rate of vegetative growth and the least 

dispersal capability of all the Floridian seagrass species (Fonseca and Kenworthy 1987) and has 

a documented slow rate of recovery from injury (Zieman 1976, Williams 1990, Fonseca and 

Kenworthy 1987, Kenworthy et al. 2000, Whitfield et al. 2002, Kirsch et al. 2005, Hammerstrom 

et al. 2007). 

Shallow seagrass beds in the Florida Keys are being negatively impacted by vessel groundings. 

The cumulative impact of these injuries has been extensive scarring of seagrass beds throughout 

the FKNMS (Sargent et al. 1995). In 2007, it was estimated that 217 reported boat groundings 

occurred in the FKNMS, with approximately 80% of these occurring on seagrass beds. This does 

not account for the hundreds more that happen every year and go unreported. 

Damages caused by vessel groundings typically include a combination of propeller scars, berms, 

and blowholes. Propeller scars are formed by the dredging effect of the turning propeller as the 

boat travels over a shallow bank. The severity (width and depth) of propeller scars varies 

depending on many factors including the size and draft of the vessel and the extent to which the 

propeller is forced into the seagrass bed. Another common injury feature, known as a blowhole, 

is formed from the concentrated force of propeller wash, either from the grounded vessel 

attempting to power off the bank or the propeller wash of the salvage vessel pulling the grounded 

vessel off the bank. The depth and area of the blowholes also vary depending on the size of the 

vessel, extent of power used to remove the vessel, and type of seagrass bed substrate. Berms, the 

third most common seagrass injury feature, are produced from sand, coral fragments, and other 
3 

materials excavated during the creation of propscars and blowholes and typically accumulate 

around the perimeter of blowholes, subsequently burying healthy seagrass. 

Damage Assessment 

[Note: The information in this section was adapted from the Discussion and Description of Injury sections of the NControl Vessel Grounding Assessment Report prepared by the NOAA Damage Assessment Center.] 

On May 29, 2001, the 45-foot Sea Ray powerboat, N-Control, ran aground on Knight Key Bank, 

a shallow seagrass bank which is approximately 0.5 kilometers (0.3 miles) northwest of 

Marathon, Florida (NOAA chart 11453 and Figure 1). Field personnel from the NOAA Damage 

Assessment Center (DAC) assessed the extent of seagrass injury caused by the N-Control on 

June 5, 2001. The assessment was conducted with differentially corrected, surveying-grade, 

digital global positioning system (DGPS) equipment. The grounding site was mapped by 

physically tracing the outline of the injury feature with the DGPS. The coordinates generated 

from the mapping were downloaded to a geographic information system (GIS) program to 

calculate the area of injury. 

This grounding incident occurred in State of Florida waters within the FKNMS and resulted in 

direct injury to a seagrass bed and additional resident species. Specifically, the injury occurred 

on a seagrass bank characterized as a Thalassia testudinum dominated seagrass community. The 

injuries from the N-Control were comprised of a blowhole, a berm, a “scrape” area caused by the 

vessel’s hull impacting the seafloor as it was turned by the salvage vessel, and two holes that 

were excavated within the scrape so the props could be removed from the vessel. The blowhole 

had an excavated planar area of 5.84 m2

 with a maximum depth of 0.7 meters below the 

surrounding seafloor. The ejected material from this blowhole created a berm due east covering 

an area of 20.92 m2. The “scrape” feature had an area of 66.04 m2 and the two holes had an area 

of 2.57 m2

 and 1.50 m2 respectively with a maximum depth of 0.5 meters below the surrounding 

seafloor. 

Percent cover of individual seagrass species, total seagrass, macroalgae and coral were 

determined using the Braun-Blanquet (BB) visual assessment method (Braun-Blanquet, 1932; 

Fourqurean et al. 2001). In this method, a numerical value is assigned based on the proportion of 

the total quadrat that is obscured by a species or functional group when observed from above. 

Only one species of seagrass, T. testudinum, was observed within the injury created by the NControl. This single species comprised no greater than 3.05% of the bottom cover within the 

injury, a nearly six-fold reduction relative to the reference area. In the reference area, two species 

were found. This area was predominantly T. testudinum with an average percent cover of 

17.50%. Percentage cover of each category is presented in Table 2. 

The total area impacted was calculated to be 96.87 m2 of seagrass habitat, predominantly 

Thalassia testudinum. 
4 

Figure 1. Location of the N-Control grounding injury at Knight Key Bank on May 29, 2001 (NOAA chart 11453). 
5 

Figure 2. Georeferenced map of the N-Control injury as surveyed June 05, 2001.

N-Control

-

Berm

Blowhole

Scrape

81°7'40"W

24°42'41"N

505 2.5

Meters
6 

Table 2. Percent cover of seagrass species, total seagrass, macroalgae, and coral present at the N-Control grounding 

site on June 05, 2001. Braun-Blanquet scores for each quadrat were converted to range midpoint values (Appendix 

B) and then averaged over the total number of quadrats assessed within each feature (total injury n=11; reference 

area n=9). Shaded columns show the calculated difference between cover in the reference area and that remaining in 

the injury area. 

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Seagrass Restoration 

Restoration is an important step in reducing the solitary and cumulative impact of seagrass 

injuries throughout the Keys. When the underground seagrass rhizome system is damaged and 

the surrounding sediment is altered by structural disturbances such as vessel groundings, the 

seagrass community experiences one of the most severe injuries possible and often has a difficult 

time re-establishing itself in the absence of restoration (Kenworthy et al. 2002). Often, nonrestored seagrass injuries are subject to secondary disturbance by storms that could impede 

recovery and/or expand the size of the injury (Whitfield et al. 2002). 

An objective in the FKNMS is to conduct feasible, cost-effective, in-kind restoration using the 

best available techniques to accelerate recovery to pre-grounding baseline levels. Depending on 

the size and severity of the injury, seagrass restoration techniques used in the FKNMS typically 

consists of one or a combination of the alternatives described in Table 3: 

Category Cover 

Remaining in 

Total Injury 

Area 

Cover in 

Reference Area 

Change in 

Cover 

T.testudinum. 3.05% 17.50% -14.45% 

H.wrightii 0.00% 0.28% -0.28% 

Total Seagrass* 3.05% 17.50% -14.45% 

Macroalgae 0.64% 7.78% -7.14% 

Coral 0.00% 4.17% -4.17% 
7 

Table 3. Alternatives for seagrass restoration in the FKNMS 

Alternative Site Condition 

No Action: Leaving the injury untouched. 

Chosen for injuries where there is a relatively 

small likelihood of secondary injury before natural 

recovery occurs, or where any restoration is 

considered too difficult to undertake due to high 

energy conditions. 

Seagrass Transplants: Planting seagrass (S. 

filiforme and H. wrightii) taken from donor sites 

into injured areas including berms, blowholes 

and/or propscars. 

Appropriate for low to moderate energy sites or 

where the probability of transplant loss due to high 

water velocity is lowest. 

Bird Stakes: Insertion of stakes upon which birds 

roost, dropping their feces on and thus fertilizing 

seagrass beds. Inserted into berms, blowholes 

and/or propscars. 

Used on seagrass beds in water depths of 1.5 

meters or less (mean high water). 

Fertilizer Spikes: Insertion of chemical fertilizer 

spikes that release fertilizer into the sediments of 

replanted seagrass beds over a period of 3-4 

months. 

Used on replanted seagrass beds when water 

depths are greater than 1.5 meters or when bird 

stakes are inappropriate due to hazards to 

navigation or risk of vandalism. 

Sediment Fill: Filling of blowholes, trenches or 

deep propeller scars with sediment similar to that 

of the surrounding area. 

Used in excavations greater than 20 centimeters 

deep. 

Sediment Tubes: Placement of biodegradable 

sediment-filled fabric mesh tubes inside the trench 

of a propscar or blowhole. 

Used as a cap for sediment fill. Tubes are often 

used in narrow excavations (such as propscars) 

deeper than 20 centimeters. 

Berm Redistribution: Returning displaced 

sediment back into the injury. 

Undertaken when doing so will prevent additional 

injury to the surrounding seagrass bed from the 

natural redistribution of the sediment that was 

displaced. Only used if the process will not cause 

more harm by damaging live seagrass below the 

berm. 

On March 25, 2003 DAC and FKNMS personnel completed the N-Control restoration. The 

primary restoration actions recommended for the N-Control included a combination of two 

alternatives: 1) the insertion of 97 bird stakes and 2) the placement of 104 planting units of H. 

wrightii. Due to changes in injury geometry post-occurrence (merging of the berm with the 

blowhole and some natural seagrass colonization on the south end of the scrape), adjustments to 

the original restoration plan had to be made on site resulting in a reduced number of bird stakes 

and planting units. In all, forty-four planting units (34 H. wrightii and 10 S. filiforme) and 39 bird 

stakes were installed within the injury (Figure 3). Though the original restoration plan called for 

H. wrightii planting units only, a combination of S. filiforme and H. wrightii was used due to the 

local availability of both species. 
8 

Figure 3. Restoration activities conducted at the N-Control injury site on March 25, 2003.

N-Control

-

" Bird Stake (40)

k H. wrightii planting unit (34)

k S. filiforme planting unit (10)

Berm

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9 

Restoration Monitoring 

Monitoring of restoration projects is necessary to determine whether the projects are providing 

services in a manner consistent with restoration goals and to assess the potential need for 

mid-course corrections to ensure that the projects meet designated restoration performance 

standards. The monitoring events reported here assessed transplant success as well as natural recolonization by measuring shoot density and aerial coverage, and collecting video 

documentation. The execution and application of the monitoring effort was adapted from 

“Guidelines for the Conservation and Restoration of Seagrasses in the United States and 

Adjacent Waters”, under “Appendices” pages 207-220, at 

http://www.cop.noaa.gov/pubs/das/das12.pdf. The monitoring data was used to determine if 

successful establishment of planted seagrass had occurred and whether the restoration was on an 

appropriate recovery trajectory. Video documentation was performed to provide a record of the 

status of the restoration. 

The following monitoring parameters were observed and/or measured at the site: 

 survival of seagrass transplants; 

 incidence of transplant expansion and/or encroachment from the adjacent, undisturbed 

seagrass population; 

 structural integrity of the bird stakes and planting units; 

 growth and survival rates of transplanted seagrass; 

 distribution and abundance of seagrass in surrounding reference areas; 

 video documentation 

The restoration monitoring plan developed for this site required six monitoring events over a 5-

year period. The events were scheduled to occur at 0.5, 1.0, 1.5, 2.0, 2.5, 3.5 and 4.5 years after 

the baseline event (installation). The actual dates and activities for each monitoring event are 

listed in Table 4. 

Table 4. Categories and Timing of Monitoring 

 

Event Date 

Completed 

Survival 

Monitoring 

Braun-Blanquet 

Abundance 

(reference and 

restored area) 

Shoot density 

(reference and 

restored area) 

Video 

Documentation 

0.5 Year 09/29/2003 x x x x 

1.0 Year 04/26/2004 x x x x 

1.5 

Year* 10/21/2004 N/A N/A x 

3.0 Year 04/17/2006 x x x 

3.5 Year 09/27/2006 x x x 

5.5 Year 08/07/2008 x x x 

*Braun-Blanquet and shoot density data were unavailable for this event. 
10 

METHODS 

Field Methods 

The N-Control restoration site was monitored using snorkel gear from a small vessel (6.1 m) on 

the dates listed in Table 4. 

For each monitoring event the structural integrity of the bird stakes and planting units (if 

distinguishable) was evaluated and noted on the data sheet. The restoration area was also 

inspected visually to assess planting unit survival, coalescence of planting units, and incidence 

of colonization from adjacent, undisturbed seagrass. This information was noted on the data 

sheet at each monitoring event. 

Growth and survival rates of transplanted and colonizing seagrass in the restoration area and the 

distribution and abundance of seagrass in the reference area was determined using a modified BB 

technique (Braun-Blanquet, 1932; Fourqurean et al. 2001). PVC quadrats (0.25 m2

) were 

haphazardly placed on the substrate within the restoration site. Reference quadrats were 

distributed haphazardly throughout the undisturbed habitat surrounding the restoration site (1 to 

3 meters from the perimeter of the original injury) in order to account for any variation exhibited 

by the habitat since restoration was initiated. The contents of each quadrat were visually 

inspected. Seagrass, macroalgae, and coral were identified and assigned a cover-abundance 

scale value (BB score) based on broad cover estimations describing the total quadrat area 

obscured when viewed from directly above. BB scores ranged from zero to five: 0 = not 

present; 0.1 = solitary specimen; 0.5 = few with small cover; 1 = numerous but less than 5% 

cover; 2 = 5 to 25% cover; 3 = 25 to 50% cover; 4 = 50 to 75% cover; and, 5 = 75 to100% cover. 

Braun-Blanquet scores for each quadrat were converted to range midpoint values (see Appendix 

B) and averaged over the total number of quadrats assessed within each feature. For each event, 

the change in seagrass cover as a result of the restoration was determined by comparing the 

percentage cover of the restoration area to that of the reference area immediately surrounding the 

restoration. 

Shoot density of transplanted and colonizing seagrass in the restoration area and the seagrass in 

the surrounding reference area was quantified by counting the number of short shoots of each 

seagrass present in one 100 cm2 quadrat placed in the center of the 0.25 m2 quadrat used in the 

modified BB technique. 

Video recordings of the N-Control restoration site were made during each monitoring event 

using a Sony DCR-PC1000 digital video camera with a Mako PC1000 underwater camera 

housing or a Sony DCR-TRV900 with an Amphibico Navigator 900 underwater camera housing.
11 

Statistical Analysis 

Data analyses were performed on the 2008 reference and restoration areas for T. testudinum

shoot counts, areal coverage using Braun-Blanquet (BB) scores, and coral and macroalgae cover 

utilizing BB scores. For the shoot counts, data met all requirements for application of t-tests. 

Because the shoot counts for T. testudinum were close to zero at the time of restoration and for 

some time afterwards, the restoration area shoot counts could only approach the reference counts 

from a single direction ( i.e. from a fewer number to a greater one). Therefore, a one-tailed t-test 

was deemed appropriate for this analysis. For the other three datasets, non-parametric methods 

were used, specifically, Mann-Whitney tests. Again one-tailed analysis was utilized, since levels 

of biota within the restoration area was nearly zero at the time of restoration (except for algae; 

for it, the directionality of the test makes no difference, as evidenced by the equality seen in 

Fig.4.c). All data analyses were performed with Prism 5.03 for Windows® (GraphPad 2009) and 

Statistix 9® (Analytical Software 2008). 

Model Recovery Estimates 

Prior to restoration, a cellular automata modeling technique was used to formulate a recovery 

trajectory for the N-Control berm and the blowhole/scrape features (Fonseca et al. 2000b; 2004). 

The model used an iterative process whereby each iteration represented a time step of one year 

and yielded a grid that continually filled with cells occupied by seagrass until all cells were 

designated as being occupied. The percentage of the injury that had recovered and the remaining 

years to complete recovery were calculated at each time step for T. testudinum and S. filiforme/H. 

wrightii combined. Percent recovery was then plotted by time in years to derive the recovery 

horizon for the entire injury. The resulting regression equations were used to calculate the 

expected percent recovery based upon two scenarios: with restoration conducted at the site 

(actual location and number of planting units); and without restoration (natural recovery from the 

surrounding population). 

Calculated Recovery Estimates 

From the original Braun-Blanquet cover estimates at each site, the following Density (D) statistic 

was calculated for the restoration area by seagrass species: 

n 

Di = Σ Sij / n

j=1 

where Di = density of species i; j = quadrat number from 1 to n, the total number of quadrats 

sampled in the restoration area; and Sij = the Braun-Blanquet score for species i in quadrat j

(Kenworthy et al. 1993; Fourqurean et al. 2001). Seagrass percent natural recovery by species 

was calculated following Uhrin et al. (2009): 

% Recovery = (Dir / Dic) x 100 
12 

where Dir = density of species i from samples r taken from directly within the restoration area 

and Dic = density of species i from control (reference) samples c taken at the time of each 

monitoring event. 

RESULTS 

0.5 Year Monitoring Event (September 29, 2003) 

On this event, the restoration area was missing ten bird stakes and it was decided not to replace 

themdue to the increase in coverage of H.wrightii at the site. Seagrass planting units were no 

longer discernable due to coalescence and recolonization from the surrounding populations of H. 

wrightii and S. filiforme. From the data obtained using the modified Braun-Blanquet technique, 

T. testudinum, H. wrightii and S. filiforme were observed in the reference area and in the 

restoration area. Percent cover of each category is presented in Table 5. The average shoot 

density of transplanted and colonizing seagrass in the restoration area is presented in Table 6. 

Shoot density data was not collected in the reference area for this event. 

Table 5. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the N-Control on September 

29, 2003. Reference n=10; Restoration n=10.

Category Cover in Restoration 

Area 

Cover in Reference 

Area Difference in Cover 

T.testudinum 0.5% 12.5% -12.0% 

S. filiforme 0.1% 0.9% -0.8% 

H.wrightii 5.0% 0.3% 4.7% 

Total Seagrass* 5.6% 13.8% -8.2% 

Macroalgae 7.4% 19.5% -12.1% 

Coral 0.0% 6.3% -6.3% 

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Table 6. Mean shoot density (±SE) of seagrass species at the N-Control on September 29, 2003. Short shoot counts 

for each quadrat (100cm2

) were averaged over the total number of quadrats assessed within the restoration area 

(n=17). 

Species Restoration Area 

S. filiforme 2.9±4.7 

H.wrightii 8.1±7.8 
13 

1.0 Year Monitoring Event (April 26, 2004) 

From the data obtained using the modified Braun-Blanquet technique, T. testudinum, H. wrightii

and S. filiforme were observed in the reference area and the restoration area. Percentage cover of 

each category is presented in Table 7. The average shoot density of transplanted and colonizing 

seagrass in the restoration area is presented in Table 8. Shoot density data was not collected in 

the reference area for this event. 

Table 7. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the N-Control on April 26, 

2004. Reference n=10; Restoration n=10.

Category Cover in Restoration 

Area 

Cover in Reference 

Area Difference in Cover 

T.testudinum 0.4% 12.6% -12.2% 

S.filiforme 1.8% 1.8% 0.0% 

H.wrightii 7.4% 0.3% 7.1% 

Total Seagrass* 10.7% 14.9% -4.2% 

Macroalgae 2.7% 5.4% -2.7% 

Coral 1.5% 19.9% -18.4% 

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Table 8. Mean shoot density (±SE) of seagrass species at the N-Control on April 26, 2004. Short shoot counts for 

each quadrat (100cm2

) were averaged over the total number of quadrats assessed within the restoration area (n=11). 

1.5 Year Monitoring Event (October 21, 2004) 

On this event the bird stakes were removed, which is standard after 18 months or when 75% 

planting unit coalescence is reached (NOAA, 2004). BB abundance and shoot density is 

unavailable for this event. Video documentation is available. 

 

3.0 Year Monitoring Event (April 17, 2006) 

At this monitoring event, one area in the original “scrape” feature remained devoid of seagrass 

and consisted of sparse macroalgae. The remaining majority of the restoration had some type of 

Species Restoration Area 

T. testudinum 0.3±0.6 

S.filiforme 3.6±7.0 

H.wrightii 3.5±8.1 
14 

seagrass coverage, either S. filiforme or H.wrightii, both of which were planted during the 

restoration. 

Using the modified Braun-Blanquet technique, two species of seagrass, T. testudinum and H. 

wrightii were observed in the reference area. In comparison, three species of seagrass, T. 

testudinum, H. wrightii and S. filiforme were observed in the restored area. Percent cover of each 

category is presented in Table 9. Shoot density of transplanted and colonizing seagrass in the 

restoration area and the seagrass in the surrounding reference area was recorded. The average 

shoot density for each species of seagrass is presented in Table 10. 

Table 9. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the N-Control on April 17, 

2006. Reference n=10; Restoration n=10.

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Table 10. Mean shoot density (±SE) of seagrass species at the N-Control on April 17, 2006. Short shoot counts for 

each quadrat (100cm2) were averaged over the total number of quadrats assessed within the restoration (n=10) and 

reference areas (n=10). 

3.5 Year Monitoring Event (September 27, 2006) 

Using the modified Braun-Blanquet technique, only T. testudinum was observed in the reference 

area. In comparison, all three species of seagrass were observed in the restoration area. Percent 

cover of each category is presented in Table 11. Shoot density of seagrass in the restoration area 

and in the reference area was recorded. The average shoot density for each species of seagrass is 

presented in Table 12. 

Category Cover in Restoration 

Area 

Cover in 

Reference Area 

Difference in Cover 

T.testudinum 2.5% 45.0% -42.6% 

S.filiforme 1.5% 0.0% 1.5% 

H.wrightii 14.3% 0.3% 14.0% 

Total Seagrass* 18.0% 45.0% -27.0% 

Macroalgae 6.1% 2.1% 4.1% 

Coral 1.8% 4.0% -2.3% 

Species Reference Area Restoration Area 

T.testudinum 8.6±2.2 0.7±1.2 

S.filiforme 0.3±0.9 9.6±7.8 

H.wrightii 0.0 0.6±1.9 
15 

Table 11. Percent cover of seagrass species, total seagrass, macroalgae, and coral at the N-Control on September 

27, 2006. Reference n=10; Restoration n=10.

 

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Table 12. Mean shoot density (±SE) of seagrass species at the N-Control restoration site on September 27, 2006. 

Short shoot counts for each quadrat (100cm2

) were averaged over the total number of quadrats assessed within the 

restoration (n=10) and reference areas (n=10). 

Species Reference Area Restoration Area 

T.testudinum 7.5±4.9 0.9±1.1 

S.filiforme 0.0 0.0 

H.wrightii 0.0 23.3±15.3 

5.5 Year Monitoring Event (August 07, 2008) 

Using the modified Braun-Blanquet technique, all three species of seagrass were observed in the 

reference and the restoration area. Percent cover of each category is presented in Table 13. Shoot 

density of transplanted and colonizing seagrass in the restoration area and the seagrass in the 

reference area was recorded. The average shoot density for each species of seagrass is presented 

in Table 14. 

Table 13. Percent cover of seagrass species, total seagrass, macroalgae and coral at the N-Control on August 07, 

2008. Reference n=10; Restoration n=10. 

Category Cover 

Remaining in 

Restoration 

Cover in 

Reference Area 

Difference in Cover 

T.testudinum 12.1% 28.8% -16.7% 

Category Cover 

Remaining in 

Restoration 

Cover in 

Reference Area 

Difference in Cover 

T.testudinum 1.3% 28.5% -27.2% 

S.filiforme 1.0% 0.0% 1.0% 

H.wrightii 27.5% 0.0% 27.5% 

Total Seagrass* 27.8% 28.5% -0.8% 

Macroalgae 4.5% 4.9% -0.4% 

Coral 0.5% 6.6% -6.1% 
16 

S.filiforme 1.0% 0.8% 0.2% 

H.wrightii 2.5% 0.8% 1.7% 

Total Seagrass* 17.0% 31.5% -14.5% 

Macroalgae 13.8% 12.5% 1.3% 

Coral 5.6% 5.1% 0.5% 

* Total Seagrass cover is scored separately and may not equal the sum of the individual species range midpoint 

values. 

Table 14. Mean shoot density (±SE) of seagrass species at the N-Control restoration site on August 07, 2008. Short 

shoot counts for each quadrat (100cm2

) were averaged over the total number of quadrats assessed within the 

restoration (n=10) and reference areas (n=10). 

Species Reference Area Restoration Area 

T.testudinum 4.9±2.8 3.2±1.9 

S.filiforme 1.2±2.7 1.7±2.5 

H.wrightii 0.3±0.9 0.7±1.5 

Summary of aerial coverage (BB) data 

From the 0.5 year monitoring event to the 5.5 year monitoring event, the percent recovery of 

total seagrass in the restoration area increased from 5.6% to 17% (Table 15). H. wrightii, one of 

the two transplanted species, reached a maximum percent recovery of 27.5% at the 3.5 year 

event and decreased to 2.5% by the 5.5 year event. The other transplanted species, S. filiforme, 

reached a maximum percent recovery of 1.8% at the 1 year event and decreased to 1% by 5.5 

year event. The climax species, T. testudinum , did not increase significantly from 0.5 year to 3.5 

year, but went from 1.3% to 12.1% from the 3.5 year to the 5.5 year events. On the 0.5 year 

event, the percent recovery of macroalgae was 7.4% and for coral was 0%. By the 5.5 year event 

the percent recovery of macroalgae in the restoration area was 13.8% and in the reference area 

was 12.5%. For coral the percent recovery in the restoration area was 5.6% and 5.1% in the 

reference area by the final monitoring event. 

Table 15. Comparison of percent recovery between the restoration (RS) and reference (RF) areas for each species 

of seagrass, total seagrass, macroalgae, and coral over the course of six monitoring events. 

Monitoring Event 0 * 0.5 1 3 3.5 5.5 

T. testudinum RS 3.0% 0.5% 0.4% 2.5% 1.3% 12.1% 

RF 17.5% 12.5% 12.6% 45.0% 28.5% 28.8% 

 

H. wrightii RS 0.0% 5.0% 7.4% 14.3% 21.8% 2.5% 

RF 0.3% 0.3% 0.3% 0.3% 0.0% 0.8% 
17 

 

S. filiforme RS 0.0% 0.1% 1.8% 1.5% 1.0% 1.0% 

RF 0.0% 0.9% 1.8% 0.0% 0.0% 0.8% 

 

Total Seagrass** RS 3.1% 5.6% 10.7% 18.0% 27.8% 17% 

 RF 17.5% 13.8% 14.9% 45.0% 28.5% 31% 

 

Macroalgae RS 0.64% 7.4% 2.7% 6.1% 4.5% 13.8% 

 RF 7.8% 19.5% 5.4% 2.1% 4.9% 12.5% 

Coral RS 0.0% 0.0% 1.5% 1.8% 0.5% 5.6% 

RF 4.2% 6.3% 19.9% 4.0% 6.6% 5.1% 

 

 *Day of injury assessment 

**Total Seagrass cover is scored separately and may not equal the sum of the individual species values 

Statistical Analysis 

The graphical depiction of results in Figure 4 shows that by the time of the August 7, 2008 (5.5 

year) monitoring event, most parameters had nearly converged between the Reference and 

Restoration areas. For the coral as well as the macroalgal cover (Figure 4c & d), no statistically 

significant differences were evident. Regarding the T.testudinum shoot count data (Figure 4a), 

which depicts Reference and Restoration area means of 4.9 and 3.2, respectively, statistical 

analysis likewise yielded no significant difference. However, significant difference was 

detected, with a p-value = 0.0376 for Thalassia areal coverage. 
18 

Figure 4. Circles indicate Braun-Blanquet scores. On shoot count graph (a) long horizontal lines represent means; 

shorter lines above and below represent +/- SEM. For all other graphs (b, c, d) long horizontal lines represent 

medians. The T. testudinum cover data (b) evidenced significant difference between the restoration and the reference 

area; there were no significant differences among the remaining datasets. 

Model Recovery Estimates 

The recovery model predicted that with the addition of the 44 planting units it would take 5.64 

years for T. testudinum to be 100% recovered in the berm,. Without planting units, the model 

predicted it would take 9.4 years. For the blowhole/scrape, it would take 22.56 years to reach 

100% with the planting units and 30.08 years without (Table 16). For H. wrightii and S. 

filiforme, the model predicted it would take 0.92 years for the berm and 3.66 years for the 

blowhole/scrape to reach 100% recovery with the addition of planting units. Without planting 

units, it would take 1.53 years for the berm and 4.88 years for the blowhole/scrape (Table 17). 
19 

Table 16. Model predicted percent recovery of T. testudinum at the N-Control restoration site. 

Years 

Berm with 

PUs 

Berm without 

PUS 

Blowhole/Scrape 

with PUs 

Blowhole/Scrape 

without PUs 

3.76 75.71% 40.24% 51.69% 28.76% 

5.64 100.00% 71.95% 

7.52 93.90% 76.78% 54.52% 

9.40 100.00% 

11.28 87.27% 70.90% 

15.04 94.01% 82.27% 

18.80 98.88% 90.97% 

22.56 100.00% 96.99% 

26.32 99.67% 

30.08 100.00% 

Table 17. Model predicted percent recovery of H.wrightii/S.filiforme at the N-Control restoration site. 

Years 

Berm with 

PUs 

Berm without 

PUS 

Blowhole/Scrape 

with PUs 

Blowhole/Scrape 

without PUs 

0.61 75.71% 40.24% 51.69% 28.76% 

0.92 100.00% 71.95% 

1.22 93.90% 76.78% 54.52% 

1.53 100.00% 

1.83 87.27% 70.90% 

2.44 94.01% 82.27% 

3.05 98.88% 90.97% 

3.66 100.00% 96.99% 

4.27 99.67% 

4.88 100.00% 

Calculated Recovery Estimates 

The density statistic (Dir) of the restoration area was inclusive of all features (blowhole/scrape 

and berm) that were restored. Based on the percent recovery calculation, T. testudinum was 66% 

recovered 5.5 years after restoration was initiated (Table 18). For H. wrightii and S. filiforme, 

percent recovery was calculated to be 200% and 133.3%, respectively, on the 5.5 year event 

(Table 18). 

Table 18. Percent recovery of T. testudinum, S. filiforme and H. wrightii at the N-Control restoration site based on 

the density statistic Di.

Year 

Density of 

Restoration 

(Dir) 

Density of 

Reference 

(Dic) 

Percent 

Recovered 

T. testudinum 

0.5 0.2 1.8 11.1% 

1.0 0.03 1.8 1.6% 

3.0 0.6 3.3 18.2% 

3.5 0.55 2.6 21.15% 

5.5 1.65 2.5 66% 
20 

S. filiforme 

0.5 0.1 0.5 20% 

1.0 0 1.6 0 

3.0 0.2 0 0 

3.5 0.4 0 0 

5.5 0.4 0.3 133.3% 

H. wrightii

0.5 0.8 0.1 800% 

1.0 0 0.3 0 

3.0 1.7 0.1 1700% 

3.5 2.2 0 0 

5.5 0.6 0.3 200% 

DISCUSSION 

The purpose of monitoring the N-Control restoration site was to determine whether successful 

establishment of the planted seagrass had occurred and if it was on an appropriate recovery 

trajectory. The monitoring data was also used to assess the potential need for mid-course 

corrections and to ensure that the restoration project was meeting designated restoration 

performance standards. 

This monitoring consisted of six events over a five and a half year period. The data collected 

using the modified Braun-Blanquet technique formed the basis of our comparison of the aerial 

coverage in the restoration and reference area. Over the monitoring period, the percent cover of 

total seagrass in the restoration area increased. We also observed an initial increase in the 

transplanted species, H. wrightii and S. filiforme, and then an eventual decrease, which occurred 

after the removal of the fertilizer source (bird stakes). The target species, T. testudinum also 

increased in percent cover in the restoration area during the monitoring period. Two other 

functional groups, macroalgae and coral, exhibited complete recovery by the final monitoring 

event. 

At this time, the FKNMS DARRP program does not actively restore Porites spp. coral in this 

habitat type. As we continue to monitor restorations in seagrass beds where Porites spp. coral 

had been injured, we have observed the eventual natural recolonization of Porites spp. back into 

the site. The presence of this coral is very important because the consolidated Porites spp. rubble 

form the geologic framework of the seagrass banks in this particular area and is essential to 

maintaining their stability (McNeill 1988). 
21 

Shoot density (no. m-2, mean ±SE) of T. testudinum, S. filiforme and H. wrightii in the restored and 

reference area. Shoot density data was unavailable for the reference area for the 0.5 and 1 year events, therefore only 

the 3, 3.5 and 5.5 year events are presented.

Based on the shoot density data, recovery was exhibited in the restoration area (Figure 5). 

Specifically, the shoot density of H. wrightii decreased post planting but then displayed rapid 

growth, typical of early colonizing seagrass species (H. wrightii and S. filiforme) in the Florida 

Keys. By the 5.5 year event, H. wrightii had decreased substantially and T. testudinum had 

become the dominant species, but had yet to reach the density of the reference area. S. filiforme

was present in the restoration area at four out of five monitoring events, but did not exhibit the 

sporadic growth seen by H. wrightii and was only observed in the reference area on the 5.5 year 

event. 

For the monitoring of this particular restoration project, the injury features were not consistently 

defined at each event, so they were combined into one “restoration area”. The recovery model, 

using the cellular automata technique, accounts for a difference in the rate of recovery between 

the blowhole/scrape and berm. For the N-Control, the berm was predicted to recover at a rate 

four times that of the blowhole with the addition of planting units. This recovery model predicted 

it would take 5.64 years for T. testudinum to be 100% recovered in the berm, and 22.56 years to 

be 100% recovered in the blowhole/scrape, with the addition of the 44 planting units. Using the 

figures from the calculated recovery estimates, a linear regression was generated and it projected 

that the “restoration area” would be 100% recovered for T. testudinum in 10.57 years (Figure 6). 

Figure 5. 

0

200

400

600

800

1000

3 3.5 5.5

Shoot density (no. m -2) Thalassia testudinum

0

50

100

150

200

250

300

3 3.5 5.5

Syringodium filiforme

0

500

1000

1500

2000

2500

3000

3 3.5 5.5

Halodule wrightii

Time (Years post restoration)
22 

Figure 6. Calculated percent recovery of T. testudinum over time post restoration. 

The N-Control ran aground in a mixed seagrass species system. In this type of habitat it is 

common for fast-growing, opportunistic species to temporarily substitute for, or even replace, the 

dominant climax species (Olesen et al. 2004). We know from existing literature that seagrass 

succession happens naturally in the Caribbean (Williams 1990, Gallegos et al. 1994, Kenworthy 

et al. 2002, Di Carlo and Kenworthy 2008) and this pattern of succession seems to hold true for 

injury features in seagrass (den Hartog 1971, 1977, Walker et al. 1989, Rasheed 1999, Olesen et 

al. 2004). The restoration area benefited from both the planting of H. wrightii and S. filiforme

and the presence of opportunistic species in the surrounding reference area. Planting seagrass in 

injured areas is known to be an effective way of stabilizing the sediments and decreasing the 

injury recovery time (Fonseca et al. 1998). Research has shown that planting faster growing, 

opportunistic species like H. wrightii or S. filiforme serves as a temporary substitute for the 

climax species, T. testudinum. This temporary substitution is referred to as “modified 

compressed succession” (Durako and Moffler, 1984; Lewis, 1987). The addition of bird stakes as 

a form of “natural” fertilizer aided in the establishment of the newly planted fast growing species 

of seagrass (Kenworthy et al. 2000). The added fertilizer also encouraged the “in-growth” of 

seagrass from the surrounding reference area. 

The goal of this restoration was to accelerate recovery of the injured area to pre-grounding 

baseline levels. The results show that the injured area is gaining seagrass and coral coverage and 

though it has yet to reach pre-grounding baseline levels for the climax species, T. testudinum, the 

coverage of the climax species is increasing. Results from the recovery model show that the time 

to 100% recovery has been reduced compared to if no restoration was conducted. This is of 

particular importance because the model was recently found to under predict recovery time of 

vessel grounding injuries (Uhrin et al. 2009). If the injury site had been left alone it could take 

11.10%

1.60%

18.20%

21.15%

66%

R2 = 0.78

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 2 4 6 8 10 12

Percent recovered

Years post restoration
23 

much longer to recover. Research has shown that natural recovery is slow, taking several years to 

several decades, depending on the location and severity of the injury (Uhrin et al. 2009 ). Larger 

polygonal injuries, particularly those where sediment has been excavated in addition to the 

seagrass rhizomes, are particularly slow to recover and may increase substantially in area and 

volume, especially if subjected to strong storms, such as hurricanes (Kenworthy et al. 2002, 

Whitfield et al. 2002, Hammerstrom et al. 2007, Di Carlo and Kenworthy 2008, Uhrin et al. in 

prep). Research on restoration techniques and natural recovery continues to provide valuable 

information on the practicality and effectiveness of seagrass restoration on vessel grounding 

injuries (Uhrin et al. 2009, Uhrin et al. in prep). In the FKNMS, seagrass restoration is a 

common practice at vessel grounding sites. There are currently over thirty ongoing restorations 

that have been implemented by the FKNMS. The data collected from the monitoring of these 

sites will also play an important role in the further development of restoration and monitoring 

techniques and recovery model development. 

ACKNOWLEDGEMENTS 

This manuscript would not have been possible without the assistance of J. Schittone, A. Stratton, 

M. Fonseca, A. Uhrin and J. Kenworthy. I am grateful for the field and technical support 

provided by L. Anderson, H. Bailey, S. Braynard, S. Donahue, W. Goodwin, K. Grimshaw, K. 

Kirsch, A. Massey, S. Meehan and R. Reardon. 
24 

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28 

Appendix A: Photo documentation of the N-Control vessel grounding, injury site and 

restoration area. 

Photo 1: The N-Control vessel aground Photo 2: The berm injury feature 

Photo 3: The scrape injury feature Photo 4: Severed T. testudinum rhizomes 

Photo 5: Bird stakes installed as part of the 

restoration.

Photo 6: An H. wrightii planting unit at the 

restoration site. 
29 

Photo 7: Evidence of expansion of an H. 

wrightii planting unit 6 months after planting.

Photo 8: Coral recruitment in the restoration 

area on the 1.0 year event. 

Photo 9: S. filiforme in the restoration area on 

the 1.0 year event. 

Photo 10: Part of the restoration area covered 

with H. wrightii on the 1.5 year event. 

Photo 11: Braun-Blanquet quadrat from the 

restoration area on the 3.5 year event. 

Photo 12: Image taken of the restoration area 

on the 5.5 year event. 
30 

Appendix B: The modified Braun-Blanquet Cover-Abundance Scale used in the estimation of 

benthic cover for this assessment. 

Braun-Blanquet (BB) Cover-Abundance Scale with Range Mid-Point Values 

BB Score Cover Range Mid-Point 

0 = Not Present 0 

0.1 = Solitary individual 1% * 

0.5 = Few, with small cover 1% * 

1 = Numerous, <5% 2.5% 

2 = 5% to 25% 15% 

3 = 25% to 50% 37.5% 

4 = 50% to 75% 62.5% 

5 = 75% to 100% 87.5% 

* Mid-point was assigned the value of 1%. Whereas the higher BB scores reference specific 

ranges in percent cover, the lower scores are primarily estimates of abundance (i.e. the number 

of individuals). 

 
1 

NMSP CONSERVATION SERIES PUBLICATIONS

To date, the following reports have been published in the Marine Sanctuaries Conservation Series. All 

publications are available on the Office of National Marine Sanctuaries Web site 

(http://www.sanctuaries.noaa.gov/). 

Dynamics of hard substratum communities inside and outside of a fisheries habitat closed area in 

Stellwagen Bank National Marine Sanctuary (Gulf of Maine, NW Atlantic) (ONMS-10-05) 

Stellwagen Bank Marine Historical Ecology Final Report (ONMS-10-04) 

Variation in Planning-Unit Size and Patterns of Fish Diversity: Implications for Design of Marine 

Protected Areas (ONMS-10-03) 

Examples of Ecosystem-Based Management in National Marine Sanctuaries: Moving from Theory to 

Practice (ONMS-10-02) 

The Application Of Observing System Data In California Current Ecosystem Assessments (ONMS-10-

01) 

Reconciling Ecosystem-Based Management and Focal Resource Conservation in the 

Papahānaumokuākea Marine National Monument (ONMS-09-04) 

Preliminary Comparison of Natural Versus Model-predicted Recovery of Vessel-generated Seagrass 

Injuries in Florida Keys National Marine Sanctuary (ONMS-09-03) 

A Comparison of Seafloor Habitats and Associated Benthic Fauna in Areas Open and Closed to Bottom 

Trawling Along the Central California Continental Shelf (ONMS-09-02) 

Chemical Contaminants, Pathogen Exposure and General Health Status of Live and Beach-Cast 

Washington Sea Otters (Enhydra lutris kenyoni) (ONMS-09-01) 

Caribbean Connectivity: Implications for Marine Protected Area Management (ONMS-08-07) 

Knowledge, Attitudes and Perceptions of Management Strategies and Regulations of FKNMS by 

Commercial Fishers, Dive Operators, and Environmental Group Members: A Baseline Characterization 

and 10-year Comparison (ONMS-08-06) 

First Biennial Ocean Climate Summit: Finding Solutions for San Francisco Bay Area's Coast and Ocean 

(ONMS-08-05) 

A Scientific Forum on the Gulf of Mexico: The Islands in the Stream Concept (NMSP-08-04) 

M/V ELPIS Coral Reef Restoration Monitoring Report Monitoring Events 2004-2007 Florida Keys 

National Marine Sanctuary Monroe County, Florida (NMSP-08-03) 

CONNECTIVITY Science, People and Policy in the Florida Keys National Marine Sanctuary (NMSP-08-

02) 

M/V ALEC OWEN MAITLAND Coral Reef Restoration Monitoring Report Monitoring Events 2004-2007 

Florida Keys National Marine Sanctuary Monroe County, Florida (NMSP-08-01) 
2 

Automated, objective texture segmentation of multibeam echosounder data - Seafloor survey and 

substrate maps from James Island to Ozette Lake, Washington Outer Coast. (NMSP-07-05) 

Observations of Deep Coral and Sponge Assemblages in Olympic Coast National Marine Sanctuary, 

Washington (NMSP-07-04) 

A Bioregional Classification of the Continental Shelf of Northeastern North America for Conservation 

Analysis and Planning Based on Representation (NMSP-07-03) 

M/V WELLWOOD Coral Reef Restoration Monitoring Report Monitoring Events 2004-2006 Florida 

Keys National Marine Sanctuary Monroe County, Florida (NMSP-07-02) 

Survey report of NOAA Ship McArthur II cruises AR-04-04, AR-05-05 and AR-06-03: Habitat 

classification of side scan sonar imagery in support of deep-sea coral/sponge explorations at the Olympic 

Coast National Marine Sanctuary (NMSP-07-01) 

2002 - 03 Florida Keys National Marine Sanctuary Science Report: An Ecosystem Report Card After 

Five Years of Marine Zoning (NMSP-06-12) 

Habitat Mapping Effort at the Olympic Coast National Marine Sanctuary - Current Status and Future 

Needs (NMSP-06-11) 

M/V CONNECTED Coral Reef Restoration Monitoring Report Monitoring Events 2004-2005 Florida 

Keys National Marine Sanctuary Monroe County, Florida (NMSP-06-010) 

M/V JACQUELYN L Coral Reef Restoration Monitoring Report Monitoring Events 2004-2005 Florida 

Keys National Marine Sanctuary Monroe County, Florida (NMSP-06-09) 

M/V WAVE WALKER Coral Reef Restoration Baseline Monitoring Report - 2004 Florida Keys National 

Marine Sanctuary Monroe County, Florida (NMSP-06-08) 

Olympic Coast National Marine Sanctuary Habitat Mapping: Survey report and classification of side scan 

sonar data from surveys HMPR-114-2004-02 and HMPR-116-2005-01 (NMSP-06-07) 

A Pilot Study of Hogfish (Lachnolaimus maximus Walbaum 1792) Movement in the Conch Reef 

Research Only Area (Northern Florida Keys) (NMSP-06-06) 

Comments on Hydrographic and Topographic LIDAR Acquisition and Merging with Multibeam 

Sounding Data Acquired in the Olympic Coast National Marine Sanctuary (ONMS-06-05) 

Conservation Science in NOAA's National Marine Sanctuaries: Description and Recent Accomplishments 

(ONMS-06-04) 

Normalization and characterization of multibeam backscatter: Koitlah Point to Point of the Arches, 

Olympic Coast National Marine Sanctuary - Survey HMPR-115-2004-03 (ONMS-06-03) 

Developing Alternatives for Optimal Representation of Seafloor Habitats and Associated Communities in 

Stellwagen Bank National Marine Sanctuary (ONMS-06-02) 

Benthic Habitat Mapping in the Olympic Coast National Marine Sanctuary (ONMS-06-01) 

Channel Islands Deep Water Monitoring Plan Development Workshop Report (ONMS-05-05) 
3 

Movement of yellowtail snapper (Ocyurus chrysurus Block 1790) and black grouper (Mycteroperca 

bonaci Poey 1860) in the northern Florida Keys National Marine Sanctuary as determined by acoustic 

telemetry (MSD-05-4) 

The Impacts of Coastal Protection Structures in California's Monterey Bay National Marine Sanctuary 

(MSD-05-3) 

An annotated bibliography of diet studies of fish of the southeast United States and Gray's Reef National 

Marine Sanctuary (MSD-05-2) 

Noise Levels and Sources in the Stellwagen Bank National Marine Sanctuary and the St. Lawrence River 

Estuary (MSD-05-1) 

Biogeographic Analysis of the Tortugas Ecological Reserve (MSD-04-1) 

A Review of the Ecological Effectiveness of Subtidal Marine Reserves in Central California (MSD-04-2, 

MSD-04-3) 

Pre-Construction Coral Survey of the M/V Wellwood Grounding Site (MSD-03-1) 

Olympic Coast National Marine Sanctuary: Proceedings of the 1998 Research Workshop, Seattle, 

Washington (MSD-01-04) 

Workshop on Marine Mammal Research & Monitoring in the National Marine Sanctuaries (MSD-01-03) 

A Review of Marine Zones in the Monterey Bay National Marine Sanctuary (MSD-01-2) 

Distribution and Sighting Frequency of Reef Fishes in the Florida Keys National Marine Sanctuary 

(MSD-01-1) 

Flower Garden Banks National Marine Sanctuary: A Rapid Assessment of Coral, Fish, and Algae Using 

the AGRRA Protocol (MSD-00-3) 

The Economic Contribution of Whalewatching to Regional Economies: Perspectives From Two National 

Marine Sanctuaries (MSD-00-2) 

Olympic Coast National Marine Sanctuary Area to be Avoided Education and Monitoring Program 

(MSD-00-1) 

Multi-species and Multi-interest Management: an Ecosystem Approach to Market Squid (Loligo 

opalescens) Harvest in California (MSD-99-1)