Evaluating%20Oyster%20Shell%20Alternatives%20for%20Enhancing/Restoring%20Shellfish%20Beds%20and%20Associated%20Impacts

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Evaluating Oyster Shell Alternatives for
Enhancing/Restoring Shellfish Beds and Associated
Impacts

• Loren Coen
• Marine Laboratory, Sanibel-Captiva Conservation
  Foundation
• lcoen_at_sccf.org

K. Schulte, A. Powers , L. M. Taylor ,
MRRI-SCDNR http//www.sccf.org,
http//www.oyster-restoration.org/
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All U.S. States (Atlantic, Gulf of Mexico, C. v.)
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Percent decline (biomass, catch, percent cover)
for fauna and flora from various marine
environments. Chart based on data from JBC
Jackson, 2008. Ecological extinction and
evolution in the brave new ocean. PNAS 105 Suppl.
1
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Oyster Shell Getting Scarce
One years shell from a single Chesapeake Bay
shucking house Typical of 19th and early 20th
centuries
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Going Elsewhere, Despite New Awareness and
Recycling
http//saltwaterfishing.sc.gov/oyster.html
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Novel Approaches/Materials For Erosion Control
Experiments by DISL (above) Sea Grant (below)
to reduce shoreline wave impacts
Units deployed for shoreline stabilization in
TX (Mad Island Reefs) along the GICWW.  
Recruitment and growth (lt 1 year)
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Overview of Talk

• Concerns about whether alternative materials or
  habitats can ever function as well as natural
  ones?
• Large-scale attempts in VA, LA, TX (sorting,
  interstitial space, longevity, weight)
• Intertidal Focus
• For intertidal oyster resource/habitat
  restoration, are any alternative materials
  feasible under a range of conditions?
• All things being equal (side by side)
• Bagged material vs. loose whelk
• Shell vs. alternative materials for use in
  areas with significant wave energy
• Designed study to evaluate this along shoreline
  in National Wildlife Refuge in SC (in progress)
• Novel methods for assessing restoration
• Following marsh erosion/mussels as stabilizers
  also

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Intertidal Oyster Reefs in Southeastern U.S.
Flats vs. Fringing Reefs
Photo by J. Monck, SCDNR
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REEF TYPE INTERSTITIAL
VOLUME Oyster shell 70
Coal Ash 58 Clam
shell 45
From M. Luckenbach
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Materials Investigated (n 7) Recruitment Trays
Range, 48 lbs SC Shell To gt70 lbs for granite and
Gulf Shell
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Seven Alternatives in Trays
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Deployed Trays in Blocks (4 total), Out for 90
Days
Each tray 2 m apart, each block is 22 m long with
15 m between blocks (n 28, 7 x 4)
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Randomized Block Design
Sign
Sign
5/07
?
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Trays Simple Way to Assess Larval Supply and
Growth
361 days (2007-08) _at_Ashepoo/Coosaw Cut,
SCORE/SCDNR
Whelk 2F, 90 days
Concrete 2A, 90 days
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Tray Recruitment Density (3 Mo.)
(n 4 7 materials)
B
B
B
?
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Tray Recruitment Size (3 Mo.)
(n 4 7 materials)
A
A
AB
B
B
C
D
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Scaling-Up in the National Wildlife Refuge
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ICW, Cape Romain NWR, SC
ICW
ICW
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Whelk Treatments, Side by Side Loose and Bagged
in High Wave Energy Area
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2.5 Months After Planting, July to Oct.
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Results After 15 Mo.
gt6 Months Post-Planting
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Site 2 R292 Cape Romain NWR
Plantings Erosion poles
In Progress samples collected this week
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Intact Intertidal Reefs as Natural Breakwaters

• Protects fringing salt-marsh
• Reduces bank erosion when developed
• Dissipate wave energy impacts

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High Wave Energy, Randomized Blocks 5 of 7
materials Folly trays 4 Reps.
Shoreline gt100 m shoreline (high erosion),
washed shell soft sediment from marsh
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Prep of Site (5 materials, 4 Reps.)
Looking from Block A to D. Each is 5 m2, 6 m
between blocks 3 m between footprints within a
block
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Delivery of Materials To Planting Site
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Experimental Design (4 blocks, 5 treatments 20)
Block 1
Rep 1
Rep 1
Rep 1
Rep 1
Rep 1
Fossil,7/07
SC, 7/07
Gulf, 7/07
Limestone, 7/07
Concrete, 7/07
Block 2
Rep 2
Rep 2
Rep 2
Rep 2
Rep 2
Fossil,7/07
Gulf, 7/07
SC, 7/07
Limestone, 7/07
Concrete, 7/07
Block 3
Rep 3
Rep 3
Rep 3
Rep 3
Rep 3
Fossil,7/07
Gulf, 7/07
SC, 7/07
Limestone, 7/07
Concrete, 7/07
Block 4
Rep 4
Rep 4
Rep 4
Rep 4
Rep 4
Gulf, 7/07
SC, 7/07
Fossil,7/07
Concrete, 7/07
Limestone, 7/07
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Five Materials Compared In NW Refuge
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Roughly 22-24 Containers Used/Footprint
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Uniform Pieces Reef 2A Limestone after 1 mo.
Little to no wash Some Spat
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Reef 1A Fossil Shell After 1 month
Little to no wash Some Spat
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Less Uniform Pieces Reef 3A Concrete after 1 mo.
Little to no wash Some Spat
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Reef 4A SC Shell, after 1 mo.
Wash
Wash
Some wash Some Spat
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Reef 5A Gulf Shell after 1 mo.
Little to no wash Some Spat
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1 Month After Planting
Spat on Fossil Shell from Reef 1A
25 spat counted on this shell
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Recruitment (gt2 mo.) Post-Planting
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Survey Grade RTK GPS (Vertical and Horizontal,
cm accuracy)
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Fossil
Gulf
Gulf
Block 1
Block 2
Blocks 3 4 not assessed
Block 3
Gulf
Block 4
?
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May 08 (10 mo.)
SC footprints, and later Gulf
shell impossible to assess
Fossil
Gulf
Gulf
Block 1
Block 2
sc
Recruitment Assessments in progress
Block 3
Gulf
Block 4
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Preliminary Results Change in Planted Material
Area July 2007 vs. May 2008 by GPS
NQ
NQ
NQ not quantifiable for SC/Gulf shell, spread
moved too much
NQ
?
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Overview/Summary

• Most materials performed reasonably well in trays
  (side by side) over an extended period of time.
  Use vs. Landfill
• Larger, poorly-sorted (variable-sized) materials
  did the best (e.g., concrete), lots of voids and
  surface area for recruits, also moved less
• Bagged materials, as demonstrated previously
  works better than loose shell, especially in
  areas with wind or boat wave impacts
• However, bagged material is not feasible for
  larger projects and still concerns about
  stabilized plastic mesh
• New molluscan shell (3) overall performed well
  relative to alternatives (4)
• Loose or bagged whelk shell consistently
  outperformed other shell, but is getting scarcer
  and scarcer to find in southeastern U.S.
• In Progress but of the shell treatments
  planted, fossil shell (FL) performed well, as did
  denser materials (e.g., concrete) in wave-washed
  areas
• Novel approaches for assessing shell cover, etc.
  especially for intertidal habitats
• Using surveying GPS can be a rapid
  cost-effective method and highly repeatable for
  assessing changes in intertidal planted
  footprints over time, shoreline erosion, etc.
• Overhead camera methods also an alternative for
  smaller areas

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Acknowledgements
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Surveys with RTK GPS