Salt marshes offer significant ecosystem functions including nutrient cycling and trophic support as a result of extremely high primary production (Barbier et al., 2011; Engle, 2011), as well as several services to humans, including coastal erosion protection, food, tourism, recreation, education, water filtration, and sustaining fisheries (Dreyer & Niering, 1995; Bertness, 1999; Barbier et al., 2011). Fiddler crabs (Uca spp.) are an essential part of salt marsh ecosystems due to their actions and contributions to food-web dynamics (Krauter 1976, Montague 1980). Among the most abundant organisms in salt marshes along the Atlantic coast (Grimes et al., 1989; Bertness & Miller, 1984), fiddler crab burrows can reach densities as high as 300 per square meter (Montague 1980; McCraith et al., 2003).

It has been found that there are significantly lower burrow abundances where active erosion is occurring at the low-marsh, as burrowing appears to be discouraged in these conditions (Luk & Zajac, 2013). A living shoreline is a termed erosion control technique comparable to natural habitat that provides a gradually sloped intertidal interface, an inhabitable environment conducive for species diversity and productivity, and helps improve water quality (Currin et al., 2010; Georgia Department of Natural Resources, 2013).

The main objective of this study is to gather baseline data on fiddler crab (Uca spp.) burrow abundance in an area of preliminary living shoreline construction. I tested the hypothesis that there will be lower burrow densities in areas of active erosion on the low marsh. It is expected that fiddler crabs will actively colonize the living shoreline.

 

In early June 2015 I established two transects 10 m in length, an experimental and control, on Mordecai Island, Ocean County, New Jersey. The experimental transect was parallel to a section of a sand filled geotube, intended to be the preliminary step in the implementation of a living shoreline. The control transect was along an adjacent shoreline without the offshore geotube barrier. Spartina stem densities were measured along both transects and were determined to be similar (Control-818/m²) (Experimental-826/m²). To quantify the distribution abundance of fiddler crab burrows, I haphazardly placed six 0.25-m2 quadrats at 2 m intervals along each transect. In each quadrat I counted all burrows and measured the burrow entrance diameter with calipers to the nearest millimeter. I censused the quadrats every two weeks from June to August 2015.

On July 23rd, I sampled burrows in the same manner as above at Money Island, Cumberland County, New Jersey where a Living Shoreline constructed with natural materials was installed in the spring of 2014.

Barbier E.B., Hacker S.D., Kennedy C., Koch E.W., Stier A.C. & Silliman B.R. 2011. The value of estuarine and coastal ecosystem services. Ecological Monographs. 81: 169–193.Bertness M.D. & Miller T. 1984. The distribution and dynamics of Uca pugnax (Smith) burrows in a New England salt marsh. Journal of Experimental Marine Biology and Ecology 83(3):211-

237.Bertness M.D. 1999. The Ecology of Atlantic Shorelines. Sunderland, MA.Currin C.A., Chappell W.S, & Deaton, A. 2010. Developing alternative shoreline armoring strategies: The living shoreline approach in North Carolina, in Shipman, H., Dethier, M.N.,

Gelfenbaum, G., Fresh, K.L., and Dinicola, R.S., eds., 2010, Puget Sound Shorelines and the Impacts of Armoring—Proceedings of a State of the Science Workshop, May 2009: U.S. Geological Survey Scientific Investigations Report 2010-5254, p. 91-102.

Dreyer G.D. & Niering W.A. 1995. Tidal Marshes of Long Island Sound: Ecology, History, and Restoration. Connecticut College Arboretum Bulletin 34.Engle V.D. 2011. Estimating the provision of ecosystem services by Gulf of Mexico coastal wetlands. Wetlands 31: 179–193.Georgia Department of Natural Resources. 2013. Living Shorelines along the Georgia Coast: A Summary Report of the First Living Shoreline projects in Georgia. Coastal Resources Division,

Brunswick, GA. plus appendix.Grimes H.H., Huish M.T., Kerby J., & Moran D. 1989. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Atlantic Marsh Fiddler.

US Fish and Wildlife Service, Biological Report 82(11.114). Lafayette, LA. 18 pp.Kraeuter J.N. 1976. Biodeposition by saltmarsh invertebrates. Marine Biology. 35: 21-5223.Luk Y.C. & Zajac R.N. 2013. Spatial ecology of fiddler crabs, Uca pugnax, in southern New England salt marsh landscapes: potential habitat expansion in relation to salt marsh change.

Northeastern Naturalist. 20(2):255-274.McCraith, B.J., Gardner, L.R., Wethey, D.S., & Moore, W.S. 2003. The effect of fiddler crab burrowing on sediment mixing and radionuclide profiles along a topographic gradient in a

southeastern salt marsh. Journal of Marine Research 61:359-390.Montague C. 1980. A natural history of temperate western Atlantic fiddler crabs (genus Uca) with reference to their impact on the salt marsh (Uca pugnax, Uca pugilator, Uca minax).

Contributions in Marine Science. 23:25-55.

We would like to thank the Misericordia University Student Summer Research Fellowship Program and the Student Research Grant program for financial support. We would also like to thank Jim Merritt and Albert Nitche of Reclam the Bay, and Josh Moody of the Partnership for the Delaware Estuary for their contributions and allowing us access to Mordecai Island and Money Island.

• Mean burrow abundance at Mordecai Island was significantly greater on the control transect compared to the experimental transect (geotubes).

• Mean burrow abundance was not significantly different between the control and experimental transect (organic living shoreline) at Money Island.

• Mean burrow diameter at Money Island was significantly smaller along living shoreline transects than control transects in the low marsh.

• The mean burrow diameter along Money Island’s living shoreline transect was significantly smaller than along Mordecai’s geotube transect.

• Our results suggest that the use of organic material is a more effective living shoreline method in enhancing fiddler crab recruitment and in reestablishing marsh habitat as compared to the use of geotubes.

A Living Shoreline Approach to Erosion Prevention and its Effect on Fiddler Crab (Uca spp.) Burrow Densities on Mordecai Island, Barnegat Bay and Money Island, Cumberland County, New Jersey 

Hunter D. Pates and Barbara J. McCraith, PhD          Department of Biology, Misericordia University, Dallas, PA

Introduction 

Methods

 Conclusions 

 References

 Acknowledgements

* = significantly different

A female fiddler (Uca pugilator) on Mordecai Island (left).

A fiddler crab burrow on Mordecai Island (right).

 Results

Money Island’s living shoreline composed of organic material such as coir fiber logs and oyster bags.

Mordecai Island’s offshore geotubes, made of a high strength woven geotextile material filled with sand.

2015 2015