Coupling carbon and energy fluxes in the North Pacific Subtropical Gyre.

The major biogeochemical cycles of marine ecosystems are driven by solar energy. Energy that is initially captured through photosynthesis is transformed and transported to great ocean depths via complex, yet poorly understood, energy flow networks. Herein we show that the chemical composition and specific energy (Joules per unit mass or organic carbon) of sinking particulate matter collected in the North Pacific Subtropical Gyre reveal dramatic changes in the upper 500 m of the water column as particles sink and age. In contrast to these upper water column processes, particles reaching the deep sea (4000 m) are energy-replete with organic carbon-specific energy values similar to surface phytoplankton. These enigmatic results suggest that the particles collected in the abyssal zone must be transported by rapid sinking processes. These fast-sinking particles control the pace of deep-sea benthic communities that live a feast-or-famine existence in an otherwise energy-depleted habitat.