CONDUCTING LARGE-SCALE INTERTIDAL OYSTER (CRASSOSTREA VIRGINICA)

RESTORATION AS MITIGATION IN SOUTH CAROLINA ESTUARINE WATERS

Michael Hodges*, William Anderson, Nancy Hadley, Holly Dyar, Allison Kreutzer

South Carolina Department of Natural Resource Office of Fisheries Management

Shellfish Management Section

Background Information• SCDNR is conducting mitigation for seaport expansion by the South Carolina State Ports Authority• Minimum of eight acres of intertidal oyster reefs will be

constructed after 5 years• 7.26 acres of shoreline have been planted at 24 sites since 2008 • Approximately 125,000 bushels of oyster shells will be planted

along shorelines in Charleston Harbor watershed • Community volunteer component to the mitigation project • Oyster reefs will be monitored for certain success criteria by

SCDNR staff

South Carolina State Ports Authority Port Expansion

•SCSPA is constructing a new 286 acre container port on the Cooper River (highlighted in red)

•This will be the 5th port in the Charleston Harbor watershed (highlighted in red)

•Currently there are two container terminals and two break bulk terminals

•The new port will increase the capacity of the Port of Charleston by 1.4 million twenty-foot equivalent units (TEU) , currently at 2.6 million TEU Photo provided by SCSPA

Required Mitigation for Port Expansion

• The SCSPA’s terminal mitigation plan includes more than $10 million in environmental and community mitigation activities.

• $1 million to restore 8 acres of oyster reefs for direct impacts to aquatic resources and wetlands

• $2.5 million to recreate 22 acres of tidal marsh on Drum Island

• $2 million for land protection for indirect environmental impacts and serve the public interest

• $4 million in community programming to fund education and job training programs, establish an affordable housing trust and other projects.

Photos courtesy of SCSPA

Oyster Restoration Mitigation Plan• SCSPA provided funding to SCDNR to be

used for the purpose of restoring, enhancing and monitoring eight acres of living oyster (Crassostrea virginica) reefs

• Reefs are to be constructed in Charleston Harbor watershed

• Reefs will be placed in intertidal areas pre-determined by SCDNR

• Planting of shells will be contracted out to industry professionals

• Planting sites will be monitored by SCDNR staff pre/post shell deployment

Why Oysters?• Oysters are designated as essential fish

habitat (EFH) by The South Atlantic Fishery Management Council (SAFMC)

• Federally managed species that depend on oysters include red drum (Scienops ocellatus)and Penaeid shrimp

• In S.C., intertidal oyster reefs generate biodiversity and are identified as critical habitats of concern in both the State Conservation Plan and DNR’s Comprehensive Wildlife Conservation Strategy

• Oysters filter water, thus improving water quality and clarity

• Intertidal oysters provide structure to aid in shoreline stabilization and erosion prevention Photo courtesy of

Affinity Charters

Charleston Harbor Watershed• Consists of Charleston Harbor (20.7

km2), 3 Main Rivers (Cooper, Wando and Ashley Rivers), and associated Tidal Creeks

• Numerous Industrial, Commercial and Residential areas on Harbor and Main Rivers

• Part of Intercoastal Waterway (ICW)• High wave energy from currents,

container ships, recreational boat traffic

• Run off from surrounding impervious surfaces, coastal development and the SC upstate

• High commercial/recreational pressure from boating and fishing

Challenges facing Oyster Restoration

• Funding is difficult to obtain for restoration in areas closed to shellfishing

• Mitigation is one of the few avenues for obtaining funding in these areas

• Projects requiring mitigation often have a difficult time finding suitable projects that meet objectives

• Finding suitable restoration sites can be challenging in areas of interest

(i.e. wave energy/currents slope, bottom type)

Pic of closed waters

Restoration Sites

• 10.83 acres (44 sites) of restorable shoreline has been mapped with Trimble GPS Pro®

• 7.26 acres (20 large scale sites, 4 small scale) have been planted since Summer 2008

• 1.75 acres (10 sites) will be planted in 2011

• 0.625 acres will be constructed by community volunteers

Shell Supply and Deployment

• Oyster shell (Crassostrea virginica) and mined shell aggregates are purchased and delivered from Florida and North Carolina (700-900 bushels/delivery)

• Shell prices are based on cost/bushel including delivery (increasing every year)

• To date we have purchased 82,715 bushels of material

• Shell is loaded onto contractors barge with bobcat and conveyor loader

• Barge is able to transport 1200-1350 bushels per trip

• Shell is transported to predetermined sites, Transport time is between 30-120 minutes based on site location

Photo courtesy of L.Coen

Large Scale Shell Planting• Shells are deployed from barge

using high pressure water cannon at high tide

• Outer boundary of area to be restored is marked with 10’ PVC stakes

• SCDNR monitors planting of shell to insure proper placement within staked boundaries

• Volume of shell planted is based on size of restoration site (10,000-12,000 bushels/acre)

• Deployment time is 45-120 minutes

Success Criteria for Restored Reefs• >70% vertical live oyster at

the end of three years • Density, mean and max

size of oysters will be within 1 SD of natural populations after three years

• Population parameters of restored reefs will meet or exceed F1 Strata characteristics• 1,926 bushels live

oysters/acre• Size distribution after 3

years will include at least 30% recruits (<25mm) to insure reef propagation

Long Term Oyster Recruitment Tray Monitoring

1998 1999 2000 2201 2002 2003 2004 2005 2006 2007 2008 20090

1000

2000

3000

4000

5000

6000

7000

8000

Oyster Recruitment in South Carolina 1998-2009 (number of sites in column)

Year of Deployment

Oys

ter

per m

2 (+

1SE)

6 8 8 13 26 33 39 49 49 18 23 24

12 season grand mean = 4267 oysters /m2, 2 Season SPA mean = 3143 oysters/m2 (6 sites)

2003 2004 2005 2006 2007 2008 20090

1000

2000

3000

4000

5000

6000

7000

8000

9000

Oyster Recruitment at One Year Old Large-Scale Sites

Year of Deployment

Oys

ter R

ecru

itmen

t/m

2 (+

1SE)

Long Term Average= 4048 oysters/m2 SPA Average= 1321 oysters/m2

Ranking sites based on Natural Resource Restoration Targets

Clouter 3136 +- 852.08Wando 2946.6668 +- 464.36Beresford 31b 2173.33 + 430.79Wando 28b 2076 + 697.38Hobcaw 23b 1729.33 + 307.34Hobcaw 23a 1401.3332 +-119.24Horlbeck 9 1389 + 337.5Wando 35 1370.67 + 135.63Beresford 14 1060 + 214.90Beresford 1a 1028 + 52.46Horlbeck 8 813.33 + 263.54Beresford 12 810.6668 +- 462.8Hobcaw 25a 601.33 + 382.43Beresford 16 532 + 36.66Hobcaw 22 316 +- 119.28Clouter 30 241.33 + 92.73Beresford 2 157.3333 +- 60.04

Density of small oysters #/m2

Good >1400 Fair 450-1400 Poor <450

Documenting Site DevelopmentAugust 2008January 2010

Monitoring Changes in Shoreline •Changes in sediment compositionPre-construction vs. Post construction (annually)

•Spartina ExpansionPre-construction vs. Post construction(annually)

•Marsh edge erosion(annually at selected sites)

South Carolina Oyster Restoration and Enhancement Program (SCORE)

• Community-based habitat restoration and monitoring program of SCDNR

• Allows community volunteers to work with scientists to restore and monitor oyster habitat along the South Carolina coast

• Increase oyster habitat at a minimum cost to taxpayers

• Develop a citizen constituency for oysters

• Initiate a grass-roots effort to restore oysters

• Increase public awareness of the value of oysters to the ecosystem

SCORE Reefs• Uses 2/3 bushel of shell per bag• Shell bags are made and deployed by

volunteers• Can be constructed in higher energy

environments than large scale reefs• 0.625 acres will be constructed after 5

years• Increased shoreline stabilization

compared to large scale reefs• Can be used as living classrooms for

school groups• Sites can be used for volunteer fish

sampling efforts• Water quality is monitored by

volunteers at restoration sites

Volume of Shell Planted each Year

2008 2009 2010 2011 20120

5,000

10,000

15,000

20,000

25,000

30,000

35,000

Large ScaleSCOREMaintenance

Year

Bush

els P

lant

ed

Potential Impacts of Restoration• Documented Success=Future

Funding for other Mitigation Projects• >8 acres of oyster reefs established• 8 acres of habitat for fish, crab, fish

and organisms associated with oyster reefs

• Increased water filtration Improved water quality

• Denitrification• Shoreline stabilization/erosion

prevention• Involving the public in restoration

efforts

Acknowledgments• South Carolina State Ports Authority• SCORE Volunteers and Organizations• SCDNR Employees• Contract Employees (Capt Pee Wee, Capt Hatt, Froggy, Chip, Trey)• Delivery Drivers (Disco, Brian, Todd, Jim)• Shell Suppliers

Questions?