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Evaluating Oyster Shell Alternatives for Enhancing/Restoring Shellfish Beds and Associated Impacts Loren Coen Marine Laboratory, Sanibel-Captiva Conservation.

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Presentation on theme: "Evaluating Oyster Shell Alternatives for Enhancing/Restoring Shellfish Beds and Associated Impacts Loren Coen Marine Laboratory, Sanibel-Captiva Conservation."— Presentation transcript:

1 Evaluating Oyster Shell Alternatives for Enhancing/Restoring Shellfish Beds and Associated Impacts Loren Coen Marine Laboratory, Sanibel-Captiva Conservation Foundation K. Schulte *, A. Powers *, L. M. Taylor *, *MRRI-SCDNR

2 All U.S. States (Atlantic, Gulf of Mexico, C. v.) * SR Gulf

3 Percent decline (biomass, catch, percent cover) for fauna and flora from various marine environments. Chart based on data from JBC Jackson, Ecological extinction and evolution in the brave new ocean. PNAS 105 Suppl. 1

4 One year’s shell from a single Chesapeake Bay shucking house Typical of 19th and early 20 th centuries Oyster Shell Getting Scarce

5 Going Elsewhere, Despite New Awareness and Recycling Recycle Oyster Shell

6 Units deployed for shoreline ‘stabilization’ in TX (Mad Island Reefs) along the GICWW. Units deployed for shoreline ‘stabilization’ in TX (Mad Island Reefs) along the GICWW. Recruitment and growth (< 1 year) Novel Approaches/Materials For Erosion Control Experiments by DISL (above) & Sea Grant (below) to reduce shoreline wave impacts

7 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 

8 Photo by J. Monck, SCDNR Intertidal Oyster Reefs in Southeastern U.S. Flats vs. Fringing Reefs

9 REEF TYPE INTERSTITIAL VOLUME Oyster shell 70% Coal Ash 58% Clam shell 45% From M. Luckenbach

10 Materials Investigated (n = 7): Recruitment Trays Fossil Granite Recycl. Concrete Range, 48 lbs SC Shell To >70 lbs for granite and Gulf Shell

11 X Seven Alternatives in Trays

12 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) 

13 Granite, Avg. #4 Gulf Crushed Concrete, Avg. #4 SC Lime- stone, Avg. #4 Whelk Fossil Shell, Whole Block 1 Crushed Concrete Avg. #4 Fossil Shell, Whole Granite, Avg. #4 Lime- Stone, Avg. #4 GulfWhelkSC Block 2 WhelkSC Crushed Concrete, Avg. #4 Lime- Stone, Avg. #4 Granite, Avg. #4 Fossil Shell, Whole Gulf Block 3 SCGulf Crushed Concrete, Avg. #4 Lime- Stone, Avg. #4 Whelk Granite, Avg. #4 Fossil Shell, Whole Block 4 5/07 22 m 2 m tray spacing 22 m 2 m tray spacing 22 m 2 m tray spacing 22 m 2 m tray spacing Sign  Randomized Block Design

14 361 days Cut, SCORE/SCDNR Trays Simple Way to Assess Larval Supply and Growth Whelk 2F, 90 daysConcrete 2A, 90 days

15 Tray Recruitment: Density (~3 Mo.) A A A A B BB (n = 4; 7 materials) 

16 AB AA BB D C (n = 4; 7 materials) Tray Recruitment: Size (~3 Mo.) 

17 Scaling-Up in the National Wildlife Refuge

18 ICW, Cape Romain NWR, SC ICW

19 Whelk Treatments, Side by Side Loose and Bagged in High Wave Energy Area

20 2.5 Months After Planting, July to Oct.

21 Results After 15 Mo. Loose Bagged >6 Months Post-Planting

22 Site 2: R292 Cape Romain NWR Plantings Erosion poles In Progress: samples collected this week 

23  Protects fringing salt-marsh  Reduces bank erosion when developed  Dissipate wave energy impacts Intact Intertidal Reefs as Natural Breakwaters 

24 Shoreline >100 m shoreline (high erosion), washed shell soft sediment from marsh shoreline (high erosion), washed shell soft sediment from marsh High Wave Energy, Randomized Blocks 5 of 7 materials Folly trays: 4 Reps.

25 Looking from Block A to D. Each is 5 m 2, 6 m between blocks; 3 m between ‘footprints’ within a block Prep of Site (5 materials, 4 Reps.)

26 Delivery of Materials To Planting Site

27 Fossil,7/07Gulf, 7/07SC, 7/07 Limestone, 7/07 Concrete, 7/07 Fossil,7/07 Gulf, 7/07SC, 7/07 Limestone, 7/07 Concrete, 7/07 Gulf, 7/07SC, 7/07Fossil,7/07 Concrete, 7/07 Limestone, 7/07 Fossil,7/07 Limestone, 7/07 Concrete, 7/07 SC, 7/07Gulf, 7/07 Rep 1 Rep 2 Rep 3 Rep 4 Block 1 Block 2 Block 3 Block 4 Experimental Design (4 blocks, 5 treatments = 20)

28 Reef 3A, Recycled Concrete Reef 1A, Fossil Shell Reef 2A, Limestone Reef 4A, SC Oysters Reef 2B, Gulf Oysters Five Materials Compared In NW Refuge

29 Roughly Containers Used/Footprint

30 Little to no wash Some Spat Uniform Pieces Reef 2A – Limestone after 1 mo.

31 Little to no wash Some Spat Reef 1A – Fossil Shell After 1 month

32 Little to no wash Some Spat Less Uniform Pieces Reef 3A – Concrete after 1 mo.

33 Some wash Some Spat Reef 4A – SC Shell, after 1 mo. Wash

34 Reef 5A – Gulf Shell after 1 mo. Little to no wash Some Spat

35 Spat on Fossil Shell from Reef 1A 25 spat counted on this shell 1 Month After Planting

36 Recruitment (>2 mo.) Post-Planting

37 Survey Grade RTK GPS (Vertical and Horizontal, cm accuracy)

38 March 08 (8 mo.) SC footprints, later Gulf shell impossible to assess Fossil Gulf Block 1 Block 2 Block 3 Block 4 Blocks 3 & 4 not assessed 

39 May 08 (10 mo.) SC footprints, and later Gulf shell impossible to assess Gulf Fossil Gulf sc Block 1 Block 2 Block 3 Block 4  Recruitment Assessments in progress

40 Preliminary Results: Change in Planted Material Area July 2007 vs. May 2008 by GPS NQ NQ: not quantifiable for SC/Gulf shell, spread & moved NQ: not quantifiable for SC/Gulf shell, spread & moved too much NQ 

41 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 

42 Acknowledgements

43 Surveys with RTK GPS March (8 mo.) May (10 mo.)


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