Surface Water Metabolism Potential in a Tropical Estuary, Hilo Bay, Hawai’i, USA, During Storm and Non-storm Conditions

Abstract

Surface water gross primary production potential (pGPP), respiration (RESP), metabolism potential (pMET), and CO2 fluxes in Hilo Bay, Hawai'i, USA, were examined along two river plumes during storm (high-flow) and non- storm (low-flow) conditions. Significant differences in pGPP, RESP, and pMET were found between low- and high-flow conditions, with lowest rates of all processes occurring during high-flow conditions. CO2 fluxes were influenced by metabolic processes at all but one site, with the bay's surface waters being autotrophic and a sink for atmospheric CO2 during low-flow conditions and less autotrophic and a source of atmospheric CO2 during high- flow conditions. Significant differences in pMET were found between the two river plumes during low-flow conditions at spatial scales of 1.5 km; however, no differences between river plumes were found during high- flow conditions. Our study suggests that an increase in storms associated with global climate change could impact surface water metabolic dynamics of tropical estuaries.