Providing Nature a Right of Way: Adapting to Sea-Level Rise in the Northwest

Estuarine vegetation communities provide critical habitat to diverse assemblages of species including migratory birds, resident shorebirds, and anadromous or resident fishes.  Vegetation communities are distributed across a saline gradient from low tidal habitats through salt and brackish marsh types.  Predicted increases in sea-level have the potential to flood current vegetation communities and push the boundary between fresh and salt water further inland.

We will discuss the results of recent sea-level rise modeling work in several of the major estuaries along the Washington and Oregon coast.  The results of this work show significant changes in vegetation communities in some estuarine systems including the loss of low tidal habitats and shifting quantities and configurations of salt marsh, brackish marsh and other transitional marsh types.  We review the extent of the projected habitat type changes and their potential effect on salmonids and other wildlife.

Allowing coastal systems to migrate inland could compensate for the loss of current vegetation communities.  However, much of the coast is now bordered by hard sea walls or earthen dikes that prevent this thereby causing wetlands seaward of barriers to gradually drown as the sea rises.  Sea-level rise modeling can be used, however, to identify coastal areas that can be returned to the sea thereby mitigating for areas lost in front of barriers.  Protecting these areas from development using a carefully planned land protection strategy is a first step in combating the effects of sea- level rise.