Mālama Loko Iʻa: Salinity and Primary Productivity Relationships at Honokea Loko. Hale o Lono, and Waiāhole/Kapalaho on Hawaii Island, Hawaiʻi

Abstract

Along the coastlines of the Hawaiian Islands, there is a valuable and critical resource known for its brackish water habitat – loko i‘a (Hawaiian fishponds). They are dynamic systems dependent on the balance between fresh groundwater inputs from uka (uplands) and landward flow of kai (seawater), which all vary depending on the behavior of our climate, including rainfall, tides, and storms. Nutrient-rich groundwater mixing with the seawater at the coast allows for an abundant growth of limu or primary productivity attracting many of Hawaii’s favorable native brackish water and herbivorous species. Having an intimate relationship with this natural coastal nursery, Hawaiians effectively modified these coastal habitats into loko i’a to provide a sustainable food source for the communities in which they reside. In support of these invaluable resources and practices, this study seeks to understand primary productivity and salinity relationships along the same coastline at Honokea Loko of Waiuli, and Hale o Lono and Waiāhole/Kapalaho of Honohononui, Hawaii. Weekly water quality monitoring by kiaiʻ loko (fishpond steward) and biweekly water column sampling, salinity in the three loko i’a ranged from 3.1 to 18.8 and was significantly different throughout different areas of each pond. Benthic primary productivity experiments, found significantly more growth at higher salinity locations across all sites. Due to these strong correlations, loko iʻa communities would greatly benefit from these methodologies to quantify the variability of environmental changes through time and specific impacts of climate phenomena, changes in rainfall and sea level. These factors have the potential to interfere with primary productivity and alter loko iʻa systems interactions entirely.