Salt Marsh Erosion Control. Danielle Kreeger Partnership for the. Haskin Shellfish Research Lab Rutgers University

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1 Mussel Powered Living Shorelines for Salt Marsh Erosion Control Danielle Kreeger Partnership for the Delaware Estuary David Bushek Haskin Shellfish Research Lab Rutgers University Other Scientists: Laura Whalen, Joshua Moody and Angela Padeletti Funding: National Fish and Wildlife Foundation, NJ DEP Coastal Management Program, New Jersey Sea Grant

2 Delaware Estuary Spartin na Marsh The Problem

3 Shoreline Erosion Courtesy D. Bushek, Rutgers Courtesy J. Gebert, ACOE

4 Severely Stressed 35% Minimally or Not Stressed 17% Moderately Stressed 48%

5 Tidal marshes need to move: Horizontally and/or Vertically Slide adapted from Michael Craghan, Rutgers DK 5

6 Delaware Estuary Livin ng Shoreline Initiative Shellfish as Natural Breakwaters Oysters South Carolina Absorb wave energy and trap sediments Reduce bank erosion Protect salt marsh Non-target ecoservices: habitat creation, water filtration, carbon sequestration and nutrient sinks Slide from Dave Bushek, Rutgers

7 Ecosystem Engineers Ribbed Mussels

8 Ribbed Mussels: An Alt ternative To Oysters Geukensia demissa Similar ecological services Not harvested Protect salt marsh Reduce wave energy and bank erosion Trap silt, building levees Trap nutrients which fertilize plants Filter water Enrich habitat for other biota Combine with oysters and marsh plants for greater impact

9 Kathy Klein Mussel Spartina Mutualism

10 Observation: Erosion appears inversely proportional to mussel density Shoreline erosion at the Maurice River

11 Delaware Estuary Livin ng Shoreline Initiative Pilot Study in themaurice River D Objective: Develop tactics to combat shoreline erosion and enhance condition along eroding coastal marshes. C B Approach: Use natural materials that slow erosion and attract assemblages of mussels, oysters and plants as intertidal reefs along the marsh edge Question: Which methods and materialsperform best along the energy gradient?

12 Maurice River sites Energy and erosion decreases from A to D Energy B Site B - Highest Energy Tested A At each site, various treatments were deployed and untreated areas were left as controls

13 Living Shorelines

14 Coir Logs and Mats can they attract mussel recruitment? Fibrous structure can attractnatural mussel recruitment if larvae are abundance Mussels can be seeded from wild populations, hatcheries or shellfish gardeners Mussels (and plants) can be salvaged from areas of erosion

15 DELSI Methods: Log Deployment

16 Coir biolog Coir mat Coir biolog Shell bags Marsh edge Upper terrace Root mass Lower terrace Peat mass water Adapt treatments to varying erosion and shoreline conditions

17 Importance of Shellfish to Early Success the Delaware Estu uary Watershed

18 Monitoring: Sediments are trapped quickly and generate rich benthic algae mats. Mussels and grass seeded into logs are surviving and growing well. Evidence of good mussel and oyster recruitment t to coir and cultch.

19 Velo ocity cm s Wave Energy at DELSI Sites Yokoyama et. al Preliminary Observations Coconut logs and mats survived best at low energy Site D # of Logs B C D Maurice River Sites Monitoring Coir Logs B C D DELSI Sites Logs Survived Logs Moved or Deflated Logs at Sites B and C did not work if tucked against marsh; likely wave slap zone Logs survived best if oyster shell bags were placed on mats in front of logs

20 Site B Highest Energy Only stakes remain where a mat and log were installed only months before. Marsh retreat is evident here day to day Logs that survived at B contained many juvenile mussel recruits

21 Site C Moderate Energy Sediment Trapping Behind Log and Shell Bags Buried Log Site C has considerable boat wake erosion. Sedime ent accretion was evident landward of treatments that survived.

22 Site D Lower Energy Sediment accreted behind and around most treatments of logs and/or shell bags Sdi Sediment ttrapping bhidl behind log Mat + Log Most effective deployments were where ebb runoff was reduced such as by this closed off scallop

23 Site D1 Lower Energy March months Log + Log + Shell Bags

24 Site D1 Lower Energy October months Log + Log + Shell Bags

25 Site D1 Lower Energy March 31, months Log + Log + Shell Bags

26 Site D Most Suitable Conditions Sediment Elevation Changes Site D 120 Log + Log + Shell Bags % Sediment Elevation Increase Log Double Log Shellbag + Log Control Treatment Type

27 Conclusions Shellfish based living shorelines provide a new tactic to slow marsh erosion by trapping sediment and stabilizing ing edge commun nities at low moderate energy sites, compared with controls Ribbed mussels (and oysters) successfully attached onto natural substrates used in this living shoreline design. Planting with salvage ed mussels and grass enhanced success. DELSI provides a promising new appro ach for stemming salt marsh loss in some areas, the long term benefits need to be assessed. More substantial tactics will be neededin high energy areas DRBC Supermussels

28 DELSI Next Steps Continue measuring sedimentation, shellfish and Spartina recruitment, and changes in shoreline relative to control sites Validate/quantify relationship between erosion and marsh mussels Assess habitat use by other fish and wildlife Expand to additional sites and more specialized applications Adjacent to marina s, on private property Explore as alternative to bulkheads and rip rap Create a educational outreach de emonstration project

29 Thank you