Utilization of a citizen monitoring protocol to assess the structure and function of natural and stabilized fringing salt marshes in North Carolina

Abstract

Narrow fringing salt marshes dominated by Spartina alterniflora occur naturally along estuarine shorelines and provide many of the same ecological functions as more extensive marshes. These fringing salt marshes are sometimes incorporated into shoreline stabilization efforts. We obtained data on elevation, salinity, sediment characteristics, vegetation and fish utilization at three study sites containing both natural fringing marshes and nearby restored marshes located landward of a stone sill constructed for shoreline stabilization. During the study, sediment accretion rates in the restored marshes were approximately 1.5-to 2-fold greater than those recorded in the natural marshes. Natural fringing marsh sediments were predominantly sandy with a mean organic matter content ranging between 1.5 and 6.0%. Average S. alterniflora stem density in natural marshes ranged between 130 and 222 stems m À2 , while mean maximum stem height exceeded 64 cm. After 3 years, one of the three restored marshes (NCMM) achieved S. alterniflora stem densities equivalent to that of the natural fringing marshes, while percentage cover and maximum stem heights were significantly greater in the natural than in the restored marshes at all sites. There was no significant difference in the mean number of fish, crabs or shrimp captured with fyke nets between the natural and restored marshes, and only the abundance of Palaemonetes vulgaris (grass shrimp) was significantly greater in the natural marshes than in the restored ones. Mean numbers of fish caught per 5 m of marsh front were similar to those reported in the literature from marshes adjacent to tidal creeks and channels, and ranged between 509 and 634 fish net À1 . Most of the field data and some of the sample analyses were obtained by volunteers as they contributed 223 h of the total 300 h spent collecting data from three sites in one season. The use of fyke nets required twice as many man-hours as any other single task. Vegetation and sediment parameters were sensitive indicators of marsh restoration success, and volunteers were capable of contributing a significant portion of the labor needed to collect these parameters.

Where is the avoidance in the implementation of wetland law and policy?

“…While the use of citizen scientists is a relatively recent phenomenon, citizens are increasingly being included in conservation and restoration planning (Currin et al 2008;Oscarson and Calhoun 2007) and have been found to be effective assistants to local land managers (Sharpe and Conrad 2006). If a standard protocol is used (e.g., Christmas Bird Count), a diverse public can be used as a local resource that is capable of collecting data on both wetland structure and function (Currin et al 2008).…”

“…If a standard protocol is used (e.g., Christmas Bird Count), a diverse public can be used as a local resource that is capable of collecting data on both wetland structure and function (Currin et al 2008). By utilizing citizen participation, not only are costs lowered compared to traditional data collection methods, but local stewardship is also promoted, with local communities benefiting directly from the educational value of participation (Hudson 2001).…”

Salt marsh stabilization affects algal primary producers at the marsh edge

“…There is some evidence that current nitrate concentrations exceed levels observed several decades ago (Micheli et al 2008), suggesting some deterioration in water quality, but the lack of longterm records leaves this trend inconclusive. In response to rising sea levels, rock sills have been installed in Bogue Sound marshes since 1998 (Currin et al 2008).…”

“…The area behind the sill is then backfilled with sediment and marsh cordgrass (Spartina alterniflora) is planted. The extent to which such restored and stabilized marshes achieve ecosystem function of natural marshes is beginning to be evaluated (Currin et al 2008). Some ecosystem properties such as marsh grass density and fish abundance return fairly quickly to levels similar to natural marshes, but accretion rates and other biogeochemical processes such as soil nitrogen storage may take longer (Piehler et al 1998;Currin et al 2008).…”

“…The extent to which such restored and stabilized marshes achieve ecosystem function of natural marshes is beginning to be evaluated (Currin et al 2008). Some ecosystem properties such as marsh grass density and fish abundance return fairly quickly to levels similar to natural marshes, but accretion rates and other biogeochemical processes such as soil nitrogen storage may take longer (Piehler et al 1998;Currin et al 2008). One of the most important metrics of ecosystem function is standing stocks of primary producers (benthic micro-and macroalgae and marsh grass), though effects of sills on benthic algal primary producers have yet to be examined.…”