Assessing Salt Marsh Resilience at Moody Point, Great Bay Estuary, NH

Salt marshes are incurring stress from several anthropogenic causes: sea level rise, invasive species, eutrophication, and increased intensity and frequency of storms. These stressors are causing the marsh edge to erode and the vegetation to retreat landward. The residential community of Moody Point located along the shores of Great Bay in Newmarket, New Hampshire is particularly susceptible to these changes, and is already experiencing erosion of walking paths which will soon threaten infrastructure. To determine if Moody Point is a viable location for a coastal restoration project, the Landowner Technical Assistance Program, operated by NH DES and UNH Cooperative Extension, has assessed the property and decided to begin a long-term study on this salt marsh. For this study erosion pins (iron rebar rods) were installed horizontally into the marsh edge at 25 locations and were monitored over a four-month period to determine erosion rates. Other environmental parameters were monitored including vegetation (species composition, percent cover) and porewater (pH, salinity, redox potential, and sulfides). Preliminary data shows vegetated percent cover decreases from low marsh to high marsh, and species richness is greatest in the high marsh. Salinity, pH, and sulfide concentrations are highest in the low marsh, while the redox potential is the most negative. Comparing salinity, pH, sulfides, and redox potential to plot distance away from the vegetated edge produces a stronger relationship than comparison to plot elevation. Changes in porewater chemistry and vegetation communities may indicate more frequent flooding and higher risk of erosion.