Microbial respiration in contrasting ocean provinces via high-frequency optode assays

• DOI: 10.3389/fmars.2024.1395799
• Publication Date: 2024-06-05T04:48:42Z
• Authors: Melanie R. Cohn; Brandon M. Stephens; Meredith G. Meyer; Garrett Sharpe; Alexandria K. Nie...; Jason R. Graff; Nicolas Cassar; Adrian Marchetti; Craig A. Carlson; Scott M. Gifford
• Keywords: Mesopelagic zone; Optode; Abyssal zone; Respiration rate

Microbial respiration is a critical component of the marine carbon cycle, determining proportion fixed that subject to remineralization as opposed being available for export ocean depths. Despite its importance, methodological constraints have led an inadequate understanding this process, especially in low-activity oligotrophic and mesopelagic regions. Here, we quantify rates low 0.2 µ mol O 2 L -1 d contrasting productivity provinces using oxygen optode sensors identify size-fractionated trends. In region North Pacific Ocean at Station Papa, surface whole water microbial was relatively stable 1.2 . Below surface, there decoupling between bacterial production coincided with increased phytodetritus small phytoplankton. Size-fractionated analysis revealed cells <5 m were responsible majority Pacific, both below mixed layer. At Atlantic Porcupine Abyssal Plain, higher (1.7 ) than decreased by 3-fold euphotic zone. The size-fraction contributions total shifted on order days during evolution phytoplankton bloom regular storm disturbances. high-resolution method used captured these significant shifts consistent coinciding stain-based methods historical site estimates. This study highlights dynamic nature across vertical, temporal, factors, emphasizing need sensitive, high-throughput techniques better understand ecosystem metabolism.