Mapping erosion potential of the urban coastal fringe in Jamaica Bay, NY

Background/Question/Methods

Jamaica Bay, a unit of the Gateway National Recreation Area, on the southern shore of Long Island, New York, is a large lagoon characterized by coastal ecosystems.  The fate and resilience of Jamaica Bay’s coastal fringe is unknown in the face of combined ecological stressors, particularly storm events and sea level rise. To enhance the resilience of natural communities in the area, we must understand the impacts of these stressors and the changes in ecosystem services as a result. Ecosystem services are the benefits that humans receive via ecological function either directly or indirectly from a given type of ecosystem. Typically land managers use ecosystem services to assess the value of an ecosystem and allocate resources efficiently. 

We performed a spatial assessment of the Jamaica Bay coastal fringe using the modeling tool InVEST to assess the value of ecosystem services (e.g. coastal resiliency and protection) provided by marsh islands.  We modeled erosion potential under two scenarios: 1) current habitat, and 2) removal of marsh islands, a possible consequence of sea level rise.

Results/Conclusions

The model projects that 17% of the shoreline would be erodible under current conditions compared to 20% given removal of marsh islands.  Most of the vulnerable shoreline is projected to be along the Rockaway Peninsula; very little of the potentially erodible areas are projected to be along the interior shoreline of the bay.  Areas that are projected to experience a slightly higher degree of erosion given removal of the marsh islands are mostly along the northern edge of the Rockaway Peninsula.  This demonstrates that the marsh islands are possibly providing some degree of protection to the northern Rockaways but not the rest of the shoreline areas of the bay.  Thus, the removal of marsh islands, possibly through sea level rise, is projected to slightly increase erosion in discreet areas in the bay.

Our results help us identify particularly valuable and vulnerable areas and guide restoration efforts in this sensitive coastal ecosystem given possible sea level rise.  Managers can also use information from our modeling efforts to predict loss of ecosystem services, resilience and vulnerability to future storms.