1. Majbritt Bolton-Warberg
Shoreline Stabilization and Changes in Sediment Composition Associated with Small-Scale Oyster Reefs in South Carolina
Michael Hodges
Nancy Hadley
Loren Coen
Steve Roth
Lindsay Goodwin
Majbritt Bolton-Warberg

2. The South Carolina Oyster Restoration and Enhancement Program (SCORE) was established to:
Involve citizens in oyster restoration activities
Educate the public and foster environmental stewardship
Utilize volunteer assistance to recycle shell
Use volunteer manpower to establish multiple research platforms annually along South Carolinas coast and aid in data collection

3. In Five Years, SCORE Has
Established 128 reefs (2,115m2) at 29 sites along 320 km of coastline
Encompassed a broad spectrum of environmental conditions
Involved over 2,000 volunteers/over 15,000 hours of service
Trained weekly water quality monitors at most of these sites

5. Typical Site Layout
14 m2

6. A Sites Firmness Can Vary Depending on Sediment Profile
Sand
Shell
Fine Sediment

7. We Monitor Regularly for the Following
Marsh erosion
Marsh expansion
Sedimentation rate and composition
Chlorophyll a
Water quality (pH, DO, Salinity, Water Clarity, Temp)
Utilization by other organisms
Population parameters
Reef observations

8. Marsh Erosion
Natural phenomenon caused by winds, waves, currents, and tides
Destabilization of fringing marsh is a cause for concern and seriously affected by erosion
Human activities such as boat traffic, wetland drainage, and dredging increase rates of erosion
Oysters act as natural breakwaters for fringing marsh to help decrease the rate of shoreline loss

9. Marsh Erosion

10. SCORE Erosion Site Results, 2001-7/06
Monthly Mean Erosion Rates
Mean Overall Erosion
Mean monthly rates ranged from
1.3 – 5.5 cm
Overall shoreline losses ranged from 40.5 – cm.
Numbers in columns indicate total length of assessment, 21 – 59 mo.

11. Erosion Rates Are Decreasing With Time Behind Reefs

12. Spartina Expansion
Although marsh edge continues to retreat, overtime Spartina is growing seaward
Expansion has been noted at 10 sites, significant expansion at 9 sites
Generally takes place years post-construction
Appears to be associated with the accumulation of soft sediments and stabilization behind reefs
Has grown seaward as much as 13 meters at some sites

13. Length of Deployment (months)
Marsh Expansion
 These are totals for the original reefs deployed at these sites, negative numbers represent retreat of marsh
Site
Mean Expansion (m)
Max Expansion
at Single Reef (m)
Length of Deployment (months)
Kiawah
-1.0 29
Boy Scout
-0.6
3.5 65
Waddell
3.3
6.3 52
Dataw
6.2
Palmetto
4.6
8.5
Trask
7.6
13.9

14. Spartina Expansion at Boy Scout
2006
2004
2002
2002
2003

15. Spartina Expansion at Dataw Island
2006
2006
2004
2002
2003
2002
2001

16. Port Royal Sound (High Energy) Expansion
2006
2003
2004

17. Charleston Harbor (High Energy) Expansion
2004
2006
2001

18. Marsh Expansion Along Entire Shoreline
2002
2005

19. (m)

20. Sediment Depth Poles
Used to measure rate at which sediments settle at reefs
Poles are 40 cm in length
Placed behind reefs
Measured quarterly or bi-annually

21. Sediment Depth Poles

22. Sediment Analysis

23. Sediment Grain Size Analysis
We wanted to examine pre-construction sediment composition vs. post-construction sediment composition
There is a significant difference in the sediment composition accumulating behind reefs vs. sediment composition not associated with constructed reefs
(p= .003)
At all sites monitored , there has been an increase in the amount of fine sediments settling at our reefs.
The sediment is either washing down from above salt marshes or settling out with reduced flow rates around new reefs

24. Changes in Sediment Composition
AVG  29% (13 sites)

25. % Composition
Site/Years

26. Things To Consider When Constructing Reefs
Spacing Between Reefs
Spacing Between Reefs
Boat Ramp

27. Ways to Address Sediment and Shoreline Changes
Add Stumps Behind Reef
Elevate Back Row

28. Conclusions
Spacing of reefs is important when considering shoreline protection
Reef deployment aids in marsh expansion
Sediment compositions are changing at sites as reefs are introduced
Early adaptive management techniques will help to deal with excessive sedimentation
Using volunteers will help facilitate work load and increase community awareness on environmental concerns
Filling knowledge gaps of sheltered coastal systems

29. Future Objectives
Continue to intensely monitor erosion behind reefs and areas not associated with reefs to see if they differ significantly
Continue to monitor changes in sediment composition and marsh expansion
Use findings to establish oyster restoration metrics
Construct more reefs in Northern part of SC

30. Acknowledgements All SCORE Volunteers Community Partners
SRS Staff (past and present)
Jason Comer and Andy Jennings
Environmental Action Volunteers
Beaufort Marine Institute
Wesley Willis (RIP)
Mr. T