Tomomi Inoue, Shigeyuki Baba, Yasuaki Akaji, Shingo Miura, Nozomi Oshiro, Mio Kezuka, Ena Suarez

Mangroves of the South Kuroshio is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology). It includes the marine ecoregions of the Central Kuroshio Current and South Kuroshio. In 2020, the mapped extent of the South Kuroshio mangrove province was 8.0 km2, representing less than 0.01% of the global mangrove area; the biota is characterized by 19 true mangrove species.
Mangroves in this province are now well conserved, and their distribution is tending to expand through natural processes. Because this province is close to the northern limit of mangrove distribution, mangrove flora and fauna are adapted to low temperatures and distinct seasonality. Many of the effects of climate warming on the organisms living among mangroves remain unclear and need to be monitored.
In 2020, the South Kuroshio mangroves cover 43% more area than our estimate for 1970. Since 1996, there has been a net increase in mangrove area of 0.39%. Although this trend might continue linearly over the next 50 years, in reality, the mangrove area should plateau when the maximum potential growth area of mangroves is reached. In contrast, spatially isolated and small-scale mangrove ecosystems are vulnerable in the event of a severe disruption impacting a wide area. Under a high sea-level rise scenario (IPCC RCP8.5) ≈8.2% of the South Kuroshio mangroves would be submerged by 2060. Moreover, 0.43% of the province’s mangrove ecosystem is undergoing degradation, with the potential to increase to 1.26% within a 50-year period, based on a vegetation index decay analysis.
Overall, the South Kuroshio mangrove ecosystem is assessed as Least Concern (LC).