Adaptive Management in Coastal Louisiana Barrier Island Restoration: Improved Implementation Through Design, Monitoring and Evaluation

Over almost two decades of barrier island restoration in Louisiana, millions of dollars have been spent on dredging and placement of sediment, sand fencing and vegetative plantings. Louisiana’s barrier islands are low-lying and frequently overwashed by storm surges and waves. However, they also provide important habitat for marine and estuarine-dependent fish and macrocrustaceans, as well as providing a separation between the open Gulf of Mexico and the sheltered waters of the coastal bays. Thus they have intrinsic habitat value but within a landscape context the maintenance of the islands provides structural control to tidal exchange between the Gulf and the estuaries. In terms of the adaptive management cycle:

• Assess – the dual problems of providing habitat on the islands and maintaining the barrier between Gulf and bay were recognized early, and restoration plans were thus developed based on using natural materials rather than the, to many, more robust approaches of rock walls and breakwaters

• Design – early designs focused on recreating the characteristics of existing adjacent barriers, in terms of elevation, slope profile, and beach materials. The result was projects with varying characteristics based on local conditions.

• Implement –the Coastal Wetlands Planning Protection and Restoration Act provided funding for specific barrier restoration, including beach/shoreface, dune and backmarsh, while in other areas beneficial use of dredged material was used to build back barrier marshes.

• Monitor – both project-specific monitoring and the coast-wide Barrier Island Comprehensive Monitoring Program used a combination of field measurements and historical imagery to identify the fate of barriers built in the 1990s with century-scale trends in barrier shoreline change.

• Evaluate – the findings of monitoring have resulted in both scholarly publications and the development of extensive datasets on shoreline change that allow restoration designers and engineers to identify sustainable source areas for material and track the relative role of prior project characteristics, e.g., dune crest height, island width, dune-marsh ratio, in influencing island longevity.

• Adjust – 21^st century barrier island design and implementation, funded under new restoration initiatives, seeks to provide maximum longevity of important island components, including back marsh and shoreface to ensure the provision of fisheries habitat as the barrier islands naturally migrate

Abstract to be revised to include additional authors and more specific information on fisheries use of different barrier habitat components.