Remove invasive red mangrove to restore Kawainui estuary habitat

Mangrove removal for flood mitigation and habitat restoration

Project proposal for removal of the invasive red mangrove (Rhizophora mangle) to restore native estuarine habitat in the waterways surrounding Kawainui, Hawaiʻi's largest freshwater wetland, in Kailua, Oʻahu. The goal is to eliminate this "invasive marine weed tree" because it has reduced critical foraging and nesting habitat for endangered waterbirds, destroyed native fishponds and archaeological sites, and altered local hydrology and sedimentation patterns. Activities include a non-herbicide removal method of cutting prop-roots at low tide, continued invasive species control, and the out-planting of native plants to restore the estuary's natural biofiltration capacity and combat erosion. The project will also coordinate community engagement and education through volunteer service days and field trips.

Expected outcomes: substantial ecological and cultural restoration. Since mangroves are alien in Hawai‘i, their removal addresses the documented problem of overgrowth onto native Hawaiian archaeological sites (e.g., fishponds), which has been problematic and costly to resource managers. The effort aligns with community commitments to enhance cultural, aesthetic, recreational, and natural services. Ecologically, mangrove removal restores open habitat, reversing the reduction of prime foraging and nesting habitat for four endangered waterbird species and has been shown to favor a shift toward sandier environments, which can increase the abundance of other native aquatic species. The project serves as a pilot for adaptive ecosystem management and allows the involvement of local community and schools to actively participate in the removal of mangrove and native outplanting.

How ready is this project for implementation?

Already underway (seeking funding to accelerate/expand)

Can this project be executed by or in partnership with a state department/agency or county government? Yes: DLNR, C&C, C&C DFM