Deep-sea prokaryotic heterotrophic activity in the biogeographical provinces of the world’s ocean

Thomas Reinthaler, Taichi Yokokawa, Toshi Nagata, Gerhard Herndl

Prokaryotic heterotrophic production using radiolabeled leucine is one of the most sensitive methods assessing prokaryotic activity in the ocean and is thus useful to evaluate the impact of heterotrophic microbes on the microbial carbon pump. Here we aimed at testing the hypothesis that regional processes in the surface ocean constrain dark ocean heterotrophic activity. We divided the ocean into biogeographical provinces that provide a framework to spatially aggregate data and compare biogeochemical processes over broad regions, and analyzed a global set of about 2600 prokaryotic production measurements from a depth range of 200 – 4000 m. The prokaryotic activity decreased less with depth in the high latitude North Atlantic provinces than in the oligotrophic subtropical gyre regions. Our results generally suggest that dark ocean prokaryotic activity in the more productive North Atlantic provinces is primarily influenced by sinking organic matter derived from the surface layers. In contrast, buoyant or slowly sinking particles and dissolved organic matter partly originating from the source water regions might be relatively more important in the oligotrophic gyre regions than in the northern North Atlantic. Similar regional differences in dark ocean prokaryotic activity were also apparent in available Pacific and Arabian Sea datasets, indicating a common set of processes influencing prokaryotic activity in distinct oceanic provinces.

Functional and Evolutionary Ecology
External organisation(s)
Ehime University, University of Tokyo
Publication date
Austrian Fields of Science 2012
106026 Ecosystem research, 106022 Microbiology
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