Lower Perdido Islands

Conservation Goals

Marsh, sandy shoreline, forest and seagrass beds are all habitat types found on and adjacent to the Lower Perdido Islands. These unique habitats support a diverse array of wildlife, especially shorebirds, wading birds and waterfowl. Common birds include tricolor herons, reddish egrets, little blue herons, snowy egrets, white ibis, and brown pelicans. Great blue herons, great egrets, clapper rails, willets and woodcock also forage in the marsh. Migratory waterfowl and neotropical migrants use the area seasonally. The seagrass beds and calm, protected waters surrounding the islands provide nursery areas for coastal finfish and shellfish such as speckled seatrout, redfish, Atlantic croaker, shrimp, and blue crabs.

Due to the wide variety of biodiversity found on and around the islands, TNC’s conservation goals include protecting and sustaining wildlife habitat while maintaining recreational opportunities for the public. Achieving these goals requires pursuing strategies that focus on habitat protection and also on raising public awareness of current rules and regulations and the importance of the unique habitats of the Lower Perdido Islands. Some of the conservation strategies highlighted in TNC’s plan include:

• Planting trees and shrubs for nesting and roosting wading birds
• Controlling vegetation in shorebird nesting and loafing areas
• Cordoning off areas to maintain distance between birds and humans
• Installing signs for public awareness (seagrass, no motor, no dogs, trash, etc.)
• Enforcing rules and regulations to protect the natural resources and for public safety

Restoration Concepts

While TNC’s conservation strategies focus on management, the concept recommendations propose habitat restoration actions developed by a team of ecologists and engineers that provide large-scale, sustainable options while ensuring space for recreation. Informed by stakeholder and public feedback, hydrodynamic modeling, morphological modeling, a series of surveys, design charrettes and existing conditions, the team developed these priority restoration concepts to push towards 100% designs. This work will focus on Walker Island and Robinson Island, while maintaining Bird Island as is for recreational use. Once complete, Robinson Island will be open to the public while Walker Island will remain off limits to foot traffic just like before restoration efforts.

Designs

Once TNC and partners developed conservation and restoration goals for protecting valuable island habitats while maintaining recreational space, Moffatt & Nichol led a rigorous design process to bring ideas to reality. This involved topographic and bathymetric surveys, cultural resource surveys, hydrodynamic modeling, sediment transport studies, water level monitoring and seagrass assessments. 

On Robinson Island, the team approached designs with the goals of addressing degraded marsh habitats, increasing areas of marsh and bird habitats, and reducing erosion to balance wildlife and public uses. Moving forward, reinforcing the existing revetment on the north end will provide protection from the strong currents that erode the island. In addition, placing a thin layer of sediment in strategic locations will help increase the marsh platform for improved habitat health. Also, developing a protective dune feature on the west end will reduce erosion, provide recreational space and protect the adjacent marsh habitat.  Additional sediment placement along the eastern side of the island will cover roots exposed due to storm activity and improve upland habitat quality while stabilizing the shoreline. Overall, restoration efforts will provide almost three acres of newly created and/or restored marsh habitat and more than four acres of dune habitat.

For Walker Island, Moffatt & Nichol designed two restoration placement areas to provide significant habitat for birds and other wildlife since it is off limits to the public. The western placement area will create over five acres of high marsh habitat, around one acre of upland habitat, and some subtidal shoal habitat. The eastern placement area will address degradation of marsh habitat and maximize dune and scrub shrub habitat to restore habitat lost over time due to storms and other impacts.  This will result in over eight acres of high marsh and over three acres of upland habitat.

Each design aims to minimize impacts to existing seagrass beds surrounding the Robinson, Walker and Bird Islands. Specifically, the “hummingbird” shape of the western placement area and the “kidney bean” shape of the eastern placement area on Walker Island are designed to protect and reduce impacts to valuable seagrasses and allow room for their expansion. In these areas, the team will install native plants such as sea oats, marsh grasses and other species following sand placement. These plants will help hold the new material in place, reduce erosion on the islands, and provide shelter and foraging areas for both fish and wildlife species. 

Seagrass on the Move

While the design team made every effort to minimize impacts to seagrass beds, a few patches of seagrass existed within the sediment placement areas.  In partnership with the U.S. Army Corps of Engineers and NOAA’s National Marine Fisheries Service, we prepared a documents outlining our approach to relocating the seagrasses within impact areas and monitoring transplanted sods (plants, roots  and sediment) throughout the life of the project.  These seagrass beds are extremely valuable as they have been steadily expanding over 20+ years, contrary to other areas exhibiting drastic declines in seagrasses worldwide. Thus, our project is doing everything possible to make sure this positive trend continues.

To prepare for construction, TNC, the Dauphin Island Sea Lab, CSA Ocean Sciences, Inc., Moffatt and Nichol, and many volunteers moved over 4,000 sods of Shoalgrass (Halodule wrightii) in July and August 2024 from sediment placement areas. The team placed the sods adjacent to the southern edge of an existing healthy seagrass bed located within a protected no-motor zone and outside of the construction footprint. The sods were planted in a checkerboard pattern to cover approximately 1.5 acres.  The team will monitor the transplants for five years for survivability, adding additional plants if coverage declines. 

Looking Ahead

Moving into 2025, TNC and partners announced that the team would soon break ground for construction after hiring a local contractor based in Orange Beach, MD Thomas Construction, to lead restoration efforts. Likely, the work would begin at Robinson Island and then to Walker Island. During this time, dredging pipelines will impact normal navigation, so boaters are encouraged to navigate the area slowly and cautiously and to look for buoys and signs marking the pipelines. 

Throughout this process, TNC will post signage and regular social media updates about the status of construction activities, which will initially look “ugly” before long-term improvements to natural habitat and recreational access become more visible.