Using Floating Islands to Create Wetland and Coastal Habitat

Project Lead

Sep

Henry Pullin

Sep

Floating islands offer a range of ecological benefits such as providing critical habitat for wildlife and improving water quality. MRRI has implemented two types of floating islands: A least tern nesting platform and vegetated floating wetlands. These pilot projects are carefully monitored to assess their effectiveness and wildlife usage, with the goal of refining future designs.

Tern Nesting Platform

The least tern nesting platform is specifically designed to create a safe and suitable nesting habitat for these small, social seabirds. Constructed with dock floats, dock hardware, and lumber, the platform is topped with several inches of sand to mimic the natural beach nesting areas preferred by least terns. To encourage colonization, the platform features decoys of least terns and a solar-powered call box that plays recorded tern calls on a timed loop. Additionally, the platform includes small shelters to protect nesting birds, guardrails to prevent chicks from falling off, and gangplanks to allow juvenile birds to climb back onto the island if they need to.

Floating Wetland

Floating wetlands are an innovative and sustainable technology that replicates the ecological functions of natural wetlands. These constructed ecosystems typically consist of a floating frame or foam mat, a growing medium (either artificial or natural), and native wetland plants. Above the waterline, the vegetation offers habitat and shelter for various species, while below, the submerged roots provide additional aquatic habitat and filter suspended sediments. Floating wetlands are also effective at removing excess nutrients like phosphorus and nitrogen, helping to improve overall water quality. MRRI is actively testing multiple floating wetland designs, with several installations deployed at strategic locations throughout the district to evaluate their performance and ecological impact.

View from onboard the least tern platform, showing the decoys and the callbox.
View of the least tern platform from a distance, showing a gangplank on the left side.
A floating wetland populated with native Spartina alterniflora, secured in place by a post with a tree swallow nesting box attached.
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