Joanna C. Ellison, Nicholas J. Crameri, Ena Suarez

The Central Pacific mangrove province is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology) including the marine ecoregions of the Gilbert/Ellis Islands, Marshall Islands, Phoenix/Tokelau/Northern Cook Islands, and Samoa Islands. The Central Pacific mangroves had a mapped extent in 2020 of 4.8 km2, representing less than 0.01% of the global mangrove area. The biota is characterized by 7 species of true mangroves, and 77 associate animals are listed on the Red List of Threatened Species (RLTS) database.
While the Central Pacific islands have relatively small mangrove areas, mangroves provide a critical contribution to remote island biodiversity, and provide ecosystem benefits to adjacent corals and seagrass systems. Geomorphic settings of mangrove ecosystems include lagoonal fringes of calcareous atolls, small estuaries of Samoa, American Samoa and Wallis, and inland mangrove ponds separated from the coast that are extremely rare globally. Threats recorded include mangrove vegetation clearance and conversion, solid waste, unsustainable exploitation of mangrove wood and crabs, sand mining and erosion causing mangrove dieback, contaminated wastewater runoff and agricultural fertilisers.
The Central Pacific mangroves are Data Deficient for the majority of IUCN ecosystem classification assessment criteria, reflecting lack of on-ground mangrove research and lack of historical spatial imagery. While information available indicates mangrove net area change of -0.5% since 1996, higher resolution spatial analysis is needed. Furthermore, under a high sea level rise scenario (IPCC RCP8.5) ≈-50.8% of the Central Pacific mangroves would be submerged by 2060. Relative sea level rise trends are higher than those globally recorded owing to vertical land movement subsidence, data indicating that +1.5-2.0 mm/year should be added to the IPCC projected rates. Overall, the Central Pacific mangrove ecosystem is assessed as Endangered (EN).