ABSTRACT
Rates of consumption of dissolved organic compounds (DOC) by heterotrophic bacteria in deep-sea sediments may be estimated by evaluating the time-course fate (incorporation into macromolecules and release as respired CO2) of tracer amounts of C-labeled DOC in cold, repressurized sediment slurries. With the advent of affordable and easy-to-use pressure equipment, the recreation of deep-sea hydrostatic pressure during sample incubation shipboard is becoming standard practice for evaluating not only DOC consumption, but also a variety of other deep-sea microbial activities. The concepts that heterotrophic bacteria in deep-sea sediments are barophilic (achieving optimal rates under elevated pressures) and dominant over other size classes of benthic organisms in the cycling of organic carbon at the abyssal seafloor have been confirmed using the C-incubation approach. The C-tracer method for deep-sea sediments borrows from protocols developed by Wright and Hobbie, Williams and Askew, and Hobbie and Crawford for measuring heterotrophic microbial activity in aquatic waters, and from later modifications.
