OYSTER REEFS 101: AN ENGINEERS PERSPECTIVE Restore America s Estuaries, Tampa FL October 2012 Dr. Jon D. Risinger, Ph.D. Lead Coastal Engineer MWH Global, Inc.
THE EASTERN OYSTER CRASSOSTREA VIRGINICA Sessile Gregarious Fecund Amorphoditic 14 days Bi-Annual Spawning Oyster Life Cycle (after Berrigan et. al 1991) 11/13/2012 2
COASTAL BIO-BREAKWATERS Detached Intertidal/Submerged Segmented Modular High Relief (3-D) OysterBreak Armor Units ORA Estuaries, 2011 11/13/2012 3
BIO-ENGINEERED OYSTER REEFS 11/13/2012 4 Coast & Harbor Engineering, 2011
BIO-BREAKWATER ALTERNATIVES Reef Balls Reef BLKS Eco Disks 11/13/2012 5
BREAKWATER DESIGN VARIABLES When the breakwater is long and/or located close to shore, conditions favor TOMBOLO formation. Dally and Pope (1986) recommend: Ls/Y > 1.5-2 for single breakwater Ls/Y = 1.5 for segmented breakwater (L<Lg<Ls) L-wavelength at the structure Y-Distance of breakwater from nourished shoreline Ls-Length of breakwater structure Lg-Gap distance between adjacent breakwater segments Short breakwaters at greater distance from shore favor SALIENT formation. Dally and Pope (1986) recommend: Ls/Y > 0.5-0.67 for single & segmented breakwater 11/13/2012 6
ROCKEFELLER WILDLIFE REFUGE DEMONSTRATION PROJECTS 11/13/2012 7
ARTIFICIAL OYSTER REEF DEPLOYMENTS/EMPLACEMENTS 11/13/2012 8
OYSTER REEF BIOMETRICS Oyster shell height measurements of 50 mm were recorded after 6 months growth Oyster counts exceeding 500 per m^2 on the artificial concrete modular units Oyster Height (mm) 60 40 20 0 6-Month Oyster Reef Growth (2011) May June July 11/13/2012 9 August * * September October Oyster Height (mm) 6-Month Oyster Growth in Water Column 80 60 40 20 0 a High b Medium b Low Oyster Weight (g) 80 6-Month Oyster Weight in Water Column 60 40 20 0 a High b Low b Medium
SPAT PLATES MONITORING OYSTER SETTLEMENT Spat Plates Temperature Salinity 11/13/2012 10
SPATFALL ANALYSIS OYSTER LARVAE SETTLEMENT Spat plate data exceeded 10,000 spat/m^2 in some locations. Seasonal Spatfall Distribution (2011) 15000 2011 Seasonal Spat Counts 30000 Spatfall Distribution Fall Distribution Vertical Tiles Vertical Tiles, (Spring Spring 2011) 2011 15000 Spatfall Fall Distribution on Longshore Longshore, (Spring 2011) spat/m^2 10000 5000 spat/m^2 20000 10000 spat/m^2 10000 5000 0 March April May June August September October 0 H-Top H-Bottom M-Top M-Bottom L-Top L-Bottom 0 x=20 x=50 x=100 Longshore Distance from Brood Stock Reef (x=0 feet) 11/13/2012 11
BIOFOULING Oysters Barnacles Bryozoans Algae 11/13/2012 12
CULTCH PLATES SPAT SETTLEMENT & OYSTER RECRUITMENT 11/13/2012 13
ENGINEERING ANALYSIS: GEOMETRY, WEIGHT, & FORCES Stress Strain Displacement 11/13/2012 14
CONCRETE COMPRESSIVE STRENGTH Dolomite Clay Mix Lava Mix Clay Oyster Shell Dolomite Clay No significant difference in material strength using lightweight aggregates 11/13/2012 15
FLEXURAL MATERIAL STRENGTH 1500 y Load (lbs) 1000 500 0 Control 6 Months 2 Years 11/13/2012 16
SEDIMENT ACCRETION Pilot scale breakwater emplacements dominated by biological growth accumulated nearly 4 cubic meters of leeward sediment over 4 years. Tombolo Heavy emplacements installed for less than one year accreted 1.6 cubic meters of sediment Light emplacements accreted 0.37 cubic meters of sediment. 11/13/2012 17
VALUE ADDED ECOSYSTEM SERVICES OF OYSTER REEFS Carbon Sequestration (Blue Carbon Potential) Water Quality Wave Attenuation Sediment Accretion Living Shorelines Aquatic Habitat Sustainable Resilient Oysters were once valued primarily as a fishery resource, but today increasing attention is being focused on other ecosystem services that oysters and the reefs provide in coastal bays and estuaries (Brumbaugh & Coen, 2009). 11/13/2012 18
CASE STUDIES: BIO-ENGINEERED OYSTER REEF DEMONSTRATION PROJECTS Vermillion Bay (Low Energy) Rockefeller Refuge (High Energy) 11/13/2012 19
FUTURE RESEARCH Living Shorelines Clemson Reef Oyster Reef Sills Vegetative Plantings 11/13/2012 20
ACKNOWLEGEMENTS MWH Global, Inc. ORA Estuaries, LLC Wayfarer Environmental Technologies, LLC Louisiana State University (LSU), LSU AgCenter Clemson University BioSystems Engineering Group LDWF, Rockefeller State Wildlife Refuge Louisiana Transportation Research Center (LTRC) 11/13/2012 21
QUESTIONS