Modeling Potential Shifts in Hawaiian Anchialine Pool Habitat and Introduced Fish Distribution due to Sea Level Rise

(Uploaded by Plazi for the IPBES Invasive Alien Species Assessment) Global mean sea levels may rise between 0.75 and 1.9 m by 2100 changing the distribution and community structure of coastal ecosystems due to flooding, erosion, and saltwater intrusion. Although habitats will be inundated, ecosystems have the potential to shift inland, and endemic species may persist if conditions are favorable. Predictions of ecosystem migration due to sea level rise need to account for current stressors, which may reduce the resilience of these ecosystems. This study predicts the potential consequences of sea level rise on the groundwater-fed anchialine pool ecosystem in Hawaii. Scenarios of marine and groundwater inundation were compared with current patterns of habitat, introduced fishes, and land use. Results show that current habitats containing endemic anchialine shrimp will be increasingly inundated by marine waters. New habitats will emerge in areas that are low lying and undeveloped. Because of subsurface hydrologic connectivity, endemic shrimp are likely to populate these new habitats by moving through the coastal aquifer. In some areas, rising sea levels will provide surface connectivity between pools currently containing introduced fishes (tilapia, poeciliids) and up to 46 % of new or existing pools that do not contain these fish. Results predicting future habitat distribution and condition due to sea level rise will support conservation planning. Additionally, the interdisciplinary approach may provide guidance for efforts in other coastal aquatic ecosystems.