Sustaining Coastal Wetlands: Sea-Level, Sediments and Society

The threat of 21st century sea-level rise, combined with local subsidence, suggests to many Gulf coast residents that coastal wetlands are doomed and restoration efforts are futile. The implications of coastal wetland loss are serious both for coastal ecosystem dynamics and the fisheries production, water filtration, and wave protection roles they play for society. Predicting wetland fate and developing effective restoration approaches requires appreciation of the biogeophysical processes that sustain wetlands as sea-level rises, and how society has manipulated these processes to the detriment of wetlands.

The need for sediment to rebuild and strengthen levees, restore barrier islands, and nourish marshes has led to renewed interest in sediment sources and sinks on the coast. While sediment mining is often seen as the best approach for both stop-gap and long-term measures, the implications for borrow areas are not always fully considered. Renewable sediment supplies are limited and often restricted further by upstream management. Planning for sustainable wetlands in the future thus requires an emphasis on the processes that allow them to maintain their elevation in the face of rising sea-levels: regular flooding and draining, storm sediment pulses, nutrient supply, and dynamic estuarine salinity regimes.

The importance of coastal wetlands and their potential role in reducing the vulnerability of coastal communities has received great attention since Hurricane Katrina. As with other ecosystem goods and services provided by natural coastal systems, the assemblage of features comprising the landscape is an important influence on wave and surge attentuation. The non-linearities of service provision associated with each feature combine to reduce the vulnerability of coastal communities but also to support fisheries production, nutrient uptake, and toruist opportunities on which the communities depend. The future of coastal wetlands and the benefits they provide for communities depends on a system level approach to coastal restoration and management.