ESR 2:21-30 (2006)  -  doi:10.3354/esr002021

ABSTRACT: Climate models predict that global average sea level may rise considerably this century, potentially affecting species that rely on coastal habitat. The Northwestern Hawaiian Islands (NWHI) have high conservation value due to their concentration of endemic, endangered and threatened species, and large numbers of nesting seabirds. Most of these islands are low-lying and therefore potentially vulnerable to increases in global average sea level. We explored the potential for habitat loss in the NWHI by creating topographic models of several islands and evaluating the potential effects of sea level rise by 2100 under a range of basic passive flooding scenarios. Projected terrestrial habitat loss varied greatly among the islands examined: 3 to 65% under a median scenario (48 cm rise), and 5 to 75% under the maximum scenario (88 cm rise). Spring tides would probably periodically inundate all land below 89 cm (median scenario) and 129 cm (maximum scenario) in elevation. Sea level is expected to continue increasing after 2100, which would have greater impact on atolls such as French Frigate Shoals and Pearl and Hermes Reef, where virtually all land is less than 2 m above sea level. Higher elevation islands such as Lisianski, Laysan, Necker, and Nihoa may provide longer-term refuges for species. The effects of habitat loss on NWHI biota are difficult to predict, but may be greatest for endangered Hawaiian monk seals, threatened Hawaiian green sea turtles, and the endangered Laysan finch at Pearl and Hermes Reef. This study marks the first effort to detail the topography and evaluate sea level rise effects on NWHI species.

KEY WORDS: Sea level rise · Habitat loss · Northwestern Hawaiian Islands · Hawaiian monk seal · Green sea turtle · Laysan finch