Trends in coastal ocean conditions on Oʻahu, Hawaiʻi

Abstract

Hawai‘i’s coastal ocean environments exhibit variability across a broad array of temporal and spatial scales, from short-term fluctuations like tidal forcing, heavy rain and wind events, to long-term fluctuations like El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and global climate change. Such dynamic variability is difficult to scientifically describe, especially when environmental concerns including coastal water quality are of interest to the coastal community and ocean researchers. The Pacific Islands Ocean Observing System (PacIOOS) Nearshore Sensor Group monitors and measures coastal waters to determine the influences that water coming from both land and sea have on the nearshore environment. The installment of nearshore monitoring stations captures a wide spectrum of water quality parameters along the south shore of the island of O‘ahu, Hawai‘i. A twelve-year time-series of water quality data provided the foundation for quantifying water quality conditions across Mamala and Maunalua Bay and allowed for us to make connections between some of the environmental processes described here. Data from this collaboration shows increasing trends in water column temperature, chlorophyll a, turbidity, and pressure (depth); and decreasing trends in salinity. These data reveal a changing coastal environment, and the parameters stated above will affect O‘ahu’s coastal ecosystems and nearshore, urban setting. Hawai‘i is undergoing difficult decisions in planning to combat the effects of global climate change. Thus, the data provided in this collaboration can be a valuable contribution towards Hawai‘i’s climate change strategy and may benefit in the states approach to adaptation, resiliency, and future planning, to protect both the urban and coastal environments.