Ecological Potential of Hawaii's Fluvial Systems: A Landscape Scale Classification to Help Determine Sensitivity to Current and Future Conditions

Partners from Michigan State University and the Hawaii Fish Habitat Partnership are collaborating to identify protection, restoration, and enhancement opportunities of habitat in Hawai’i‘s streams.  Work completed in 2010 included the development of a composite disturbance index characterizing multiple impacts to fluvial habitat applied to all stream reaches state-wide.  Despite this index’s utility, streams are known to respond differently to similar levels of disturbances due to differences in natural characteristics like catchment geology, topography, and stream size.  To improve the index, we have recently classified stream reaches to characterize their natural ecological potential, with resulting classes assumed to reflect varying degrees of sensitivity to disturbances.  This classification builds on results of the Atlas of Hawaiian Watersheds and incorporates 1) natural landscape variables (i.e. stream slope, groundwater delivery) and 2) climate variables important to stream habitat.  We used CART analysis, reach-specific habitat data, and both state-wide and regional datasets of native stream biota to determine variable classes.  With streams organized into ecologically-meaningful groups, we can better characterize their sensitivity to landscape changes and also anticipate how altered landscape factors may affect organisms, allowing for better management of Hawai’i’s unique river systems now and into the future.