Characterizing mauka to makai connections on Maui for aquatic ecosystem conservation

Abstract

Mauka-to-makai connectivity –commonly referred to as ridge-to-reef –directly affects biogeochemical processes and ecological functions across terrestrial, aquatic, and marine systems. This is especially true in Hawaiʻi, where the land and sea are in close proximity. This connectivity has substantial symbolic cultural value, which is perpetuated by water flowing from uplands to the sea. The supply of freshwater to estuarine, wetland, and nearshore environments supports the food, water, and habitats utilized by endemic aquatic fauna. The ecosystem services supported by this interconnectivity supports cultural practices including fishing, aquaculture, wetland agriculture, religious ceremonies and recreational practices. To effectively guide aquatic resource management a comprehensive accounting of the connections among these environments is critical. The objective of this study was to identify spatial linkages in landscapes that promote multiple and diverse uses, following the ridge-to-reef concept, at an island-wide scale. I used diverse data, including wetland locations, indicators of freshwater input from streams, nearshore fish biomass, fishpond locations, agricultural land in watersheds, coral cover, beach recreation use, and dynamically downscaled CMIP5 future climate projections scenarios (RCP 4.5 & 8.5), to examine the spatial linkages from land to the sea. I specifically included social data in the analyses because incorporating human well-being factors such as Indigenous cultural values and traditions within resource management has been proven to be engaging, well-received by local communities, and effective to achieve sustainable usage of resources. I used the Zonation Conservation Planning Software to identify areas of high conservation prioritization to help inform aquatic resources management. I selected the Island of Maui for the pilot study as a representative island for tropical Pacific Islands. The areas of high conservation prioritization include many minimally-disturbed streams in east Maui and the coastal zones of diverse coral reefs. With this information, resource managers can incorporate the results to understand the diverse natural and social influences on habitat condition and other values in these areas, and strategically plan future management and conservation actions.