Revisiting carbon flux through the ocean's twilight zone.

Microbial gardening in the ocean's twilight zone: Detritivorous metazoans benefit from fragmenting, rather than ingesting, sinking detritus

Sinking organic particles transfer ∼10 gigatonnes of carbon into the deep ocean each year, keeping the atmospheric CO2 concentration significantly lower than would otherwise be the case. The exact size of this effect is strongly influenced by biological activity in the ocean's twilight zone (∼50-1,000 m beneath the surface). Recent work suggests that the resident zooplankton fragment, rather th...

Effects of Ocean Acidification on the Ballast of Surface Aggregates Sinking through the Twilight Zone

The dissolution of CaCO(3) is one of the ways ocean acidification can, potentially, greatly affect the ballast of aggregates. A diminution of the ballast could reduce the settling speed of aggregates, resulting in a change in the carbon flux to the deep sea. This would mean lower amounts of more refractory organic matter reaching the ocean floor. This work aimed to determine the effect of ocean...

Bacterial vs. zooplankton control of sinking particle flux in the ocean’s twilight zone

The downward flux of particulate organic carbon (POC) decreases significantly in the ocean’s mesopelagic or ‘twilight’ zone due both to abiotic processes and metabolism by resident biota. Bacteria and zooplankton solubilize and consume POC to support their metabolism, but the relative importance of bacteria vs. zooplankton in the consumption of sinking particles in the twilight zone is unknown....

Bacterial vs . zooplankton control of sinking particle flux in the ocean ’ s twilight zone 1 2

Rapid oxygen utilization in the ocean twilight zone assessed with the cosmogenic isotope

[1] The rate of oxygen utilization beneath the sunlit surface ocean provides a measure of the export rate of biologically produced carbon to the deep sea, and its variation with depth suggests where remineralization of that carbon occurs. The latter consideration is relevant to the efficiency of carbon sequestration in deep water. However, accurate characterization of this process, particularly...