Effects of shoreline reef creation on edge erosion, marsh resilience and nekton assemblages in south Louisiana

1. Effects of shoreline reef creation on edge erosion, marsh resilience and nekton assemblages in south Louisiana Megan La Peyre U.S. Geological Survey, Louisiana Fish and Wildlife Cooperative Research Unit School of Renewable Natural Resources Louisiana State University Agricultural Center Baton Rouge, LA Austin Humphries School of Renewable Natural Resources Louisiana State University Agricultural Center Baton Rouge, LA

2. Photo by Tyrone Turner – National Geographic Wetland loss 64 – 91 km2 y-1 25% of nation’s total fishery production in lower 48

3. > 500 projects Louisiana’s 2007 Master Plan: 1) hydrologic restoration 2) shore protection

4. Shore Protection Tires, Wooden Structures, Christmas trees, Concrete Limestone rock - costly ($1 million / mile) - heavy (sink) - imported from out-of-state Oyster reefs - native - sustainable - potential added ecosystem benefits

5. research objectives: examine effects of created reef size, shoreline orientation, and location on: • shoreline erosion • nekton (fish and decapod crustaceans) use • reef sustainability/oyster populations (Casas poster)

6. North West Sister Lake South “low” energy shorelines “medium” energy shorelines Gulf of Mexico

7. reef establishment: march 2009 Cost: < $300,000/linear mile “narrow” = 25 m x 1 m x 1 m “wide” = 25 m x 2 m x 1 m

8. approach Measured quarterly: • Shoreline position • Soil characteristics • Vegetation • Nekton use

9. marsh vegetation community 100% S. americanus J. roemerianus 80% S. patens 60% S. alterniflora % species composition D. spicata 40% B. maritimus 20% 0% north west south Similar production at all sites: 805.9 ± 74.0 g m-2

10. A % soil organic matter B B marsh soil properties 35 25 15 5 north west south Universal soil loss equation: increase OM 1-3%, reduces erosion 20-33%

11. shoreline change Narrow Reef A **site interaction Wide Reef 0.6 Reference AB AB 0.4 Shoreline retreat (cm d-1) B B 0.2 0 Medium Low Energy Environment

12. April 2009-August 2010 0.8 Narrow Reef Wide Reef Reference 0.6 Shoreline retreat (cm d-1) 0.4 0.2 0 North West South Medium Energy Gulf of Mexico

13. shoreline effects - sites experienced extremely high erosion (1-3 m/18 mo) - at low energy sites reefs failed to reduce retreat - at medium energy sites, site-specific effects • Restoration implications: • Need to understand local site environment, such as currents, morphology, bathymetry • Understand local weather patterns and in particular, dominant storm passages

14. sampling nekton Gillnet Seine Trays shoreline reef Quarterly: March, June, August, December 2009, 2010

15. transient species West 250 North 200 South 150 CPUE 100 50 0 Winter Summer Fall Spring 9.2 ± 0.4 5 8.6 ± 0.5 4 Water quality: only difference between sites in salinity 3 12.4 ± 0.5 1 fall winter Season Gulf of Mexico

16. Reef Mud Resident abundance CPUE June Aug Dec March 2010 2009

17. Does shell quantity impact resident abundance? 100 Adj r2 = 0.22 80 60 CPUE (# individuals/tray) 40 20 0 0 1 2 3 4 Tray shell volume (L)

18. Four treatments Mud bottom Cage structure Cage plus low volume Cage plus high shell volume Low High

19. b b abundance Mean abundance (# of indˉ²) a a Mud Cage Low High b b b Shannon diversity (H’) a diversity High Mud Cage Low

20. 6000 Oyster density (m2) 3000 0 L-N L-N L-N L-N L-N L-N M-N M-N M-N M-N M-N M-N M-W M-W M-W M-W M-W M-W nekton support - transient abundance not affected by reef presence - possible redundancy of marsh edge habitat - residents more abundant and diverse at reef sites - presence of structure per se most important factor determining assemblages • Restoration implications: • How do spatial location and adjacent habitats affect added value of reefs to transients • Does added structure impact resident communities? • How might resident species, oyster population structure affect nekton communities? 100 September 2010 dead M-N = medium energy, narrow reef M-W = medium energy, wide reef L-N = low energy, narrow reef live 75 50 Frequency of size distribution (%) June 2010 Spat: < 25 mm Seed: 25-50 mm Seed: 50-75 mm Commercial: >75 mm 25 0 North West North West South South POSTER: Casas et al.

21. What are the key parameters to consider to identify the most viable shorelines for shore protection ? 1) local site conditions: energy, currents, morphology 2) oyster population response What factors influence the value of restored fringing reefs for resident or transient nekton? 1) characteristics of structure 2) functional response of nekton

22. Grand Isle, Breton Sound, Biloxi Marsh • Experimental lab and field studies: • Location effects (shoreline, nekton, oyster populations) • Base material, size, design • Link oyster physiology, oyster population structure with nekton use • Foraging success with different structure Vermilion Bay Sister Lake

23. Funding Louisiana Department of Wildlife and Fisheries Collaborators Jerome La Peyre, Louisiana State University AgCenter Sandra Casas-Liste, Louisiana State University AgCenter Acknowledgments LA DWF – Heather Finley, Patrick Banks, Steve Hein, Willie Cheramie LSU – Shea Miller, Shannon Martin, Steve Beck, Ben Eberline, Anna Catalanello, John Gordon, Gary Decossas, Lainey Pitre, Matt Kimball Community - Wilson Voisin, Stephen Champagne, Antill Pipeline Construction Co.