Saltmarsh Elevation Monitoring
Why are wetlands important?
Wetlands provide habitat and security for many different species. Many juvenile fish and other sea creatures live in the wetlands, as well as, birds stopping in to get food. Since tides, wave energy and sediment deposit are all part absorbed by the wetlands, they prevent possible erosion and also protect inland areas from floods. Wetlands process nutrients that might otherwise enter surface waters in excess and detract from pond water quality.
With climate change, rising sea level has the potential to cover and drown wetlands, if the wetlands are not able to compensate by growing upward. Another outcome of climate change is the prevalence of short-term drought punctuated by more aggressive rain storms. This will affect the wetlands, since they are vulnerable to the impacts of pulses of fresh, turbid water. It is essential to begin as soon as possible to monitor the elevation of saltmarshes on Martha’s Vineyard to plan for the needs of these vital habitats as climate change proceeds.
How will we monitor the wetlands?
The Rod-SET system has been developed in order to precisely measure
and monitor minute changes in the elevation of saltmarshes. The monitoring stations are carefully sited and installed, and the SET survey armature is placed atop each monitoring station in turn and an array of monitoring pins is dropped to the surface and the elevation recorded. The survey armature will be used at a number of other stations around Martha’s Vineyard.
The first saltmarsh elevation monitoring site on Martha’s Vineyard is the
Sengekontacket marsh at Felix Neck Wildlife Sanctuary. Part of the response of the saltmarsh to sea level rise is to emerge by growth upward. That is what the R-SET equipment will measure. Another important planning piece is the lateral migration of marsh to adjacent areas presently in
upland habitat. The MVC is taking a hard look at upland areas where there is sufficient undeveloped land for existing saltmarsh to overtake as those lands become submerged. Lands adjacent to Sengekontacket Pond will serve as critically- important resource for such future landward migration.
The graphic illustrates the generous potential for these future saltmarsh habitat. After 1.5 feet of sea rise (by about 2050), some wetlands will be covered. The light blue represents 1.5 feet of inundation. After 5 feet of sea level rise (by about 2100) the present wetlands are completely covered. The dark blue represents 5 feet of inundation. There is adjacent upland where the marsh can grow landward as the water rises.
Felix Neck Wildlife Sanctuary is shown below after 5 feet of sea level rise (dark blue, by about 2100). This map shows the light green (conservation land) and light speckled green (undeveloped upland buffer) that make this marsh an ideal candidate for landward migration with sea level rise, and an essential first location to begin monitoring saltmarsh elevation on Martha’s Vineyard. The red circle represents the site that is the focus of the proposed elevation monitoring project. Three Rod-SET stations are installed in the marsh, to be monitored by MVC staff over the coming years. These R-SET stations will be visible from the walking path, and an informative sign will be maintained there to educate the public about what is going on and why it is important.