Constraining growth rates and the ratio of living to nonliving particulate carbon using beam attenuation and adenosine‐5′‐triphosphate at Station ALOHA

Abstract

AbstractCarbon is not only the foundation of all life on our planet, but also an element that persists in detrital material long after living organisms die. Quantifying the relative amount of living and nonliving carbon in suspended particles in the ocean is challenging and rarely done; yet it is key to understanding the fate of organic matter and informing food web models. Here, we use particulate adenosine‐5′‐triphosphate (ATP) and particulate carbon (PC) data collected as a component of the Hawaii Ocean Time‐series program to show that living particles comprise only ~ 26–42% of the total PC pool in the surface waters of the North Pacific Subtropical Gyre, regardless of time of year. Diel‐resolving particulate beam attenuation data are then used in conjunction with PC and ATP data to constrain living particle net growth rates for this system, yielding rates of ~ 0.5–0.7 d−1 year‐round. These estimates are realistic and consistent with previous microscopy and incubation‐based work in the region.