Hydrostatic pressure impedes the degradation of sinking copepod carcasses and fecal pellets

TY - JOUR

T1 - Hydrostatic pressure impedes the degradation of sinking copepod carcasses and fecal pellets

AU - Franco Cisterna, Belén

AU - Stief, Peter

AU - Glud, Ronnie N.

N1 - Data archiving: on request

PY - 2024/2/1

Y1 - 2024/2/1

N2 - Fast-sinking zooplankton carcasses and fecal pellets appear to contribute significantly to the vertical transport of particulate organic carbon (POC), partly because of low temperature that decreases microbial degradation during the descent into the deep ocean. Increasing hydrostatic pressure could further reduce the degradation efficiency of sinking POC, but this effect remains unexplored. Here, the degradation of carcasses and fecal pellets of the abundant marine copepod Calanus finmarchicus was experimentally studied as a function of pressure (0.1–100 MPa). Samples were either exposed to elevated pressure in short 1-day incubations or a gradual pressure increase, simulating continuous particle sinking during a 20-day incubation. Both experiments revealed gradual inhibition of microbial respiration in the pressure range of 20–100 MPa, corresponding to 2–10-km depth. This suggests that hydrostatic pressure impedes carbon mineralization of fast-sinking carcasses and fecal pellets and enhances the deep-sea deposition rate of zooplankton-derived organic material.

AB - Fast-sinking zooplankton carcasses and fecal pellets appear to contribute significantly to the vertical transport of particulate organic carbon (POC), partly because of low temperature that decreases microbial degradation during the descent into the deep ocean. Increasing hydrostatic pressure could further reduce the degradation efficiency of sinking POC, but this effect remains unexplored. Here, the degradation of carcasses and fecal pellets of the abundant marine copepod Calanus finmarchicus was experimentally studied as a function of pressure (0.1–100 MPa). Samples were either exposed to elevated pressure in short 1-day incubations or a gradual pressure increase, simulating continuous particle sinking during a 20-day incubation. Both experiments revealed gradual inhibition of microbial respiration in the pressure range of 20–100 MPa, corresponding to 2–10-km depth. This suggests that hydrostatic pressure impedes carbon mineralization of fast-sinking carcasses and fecal pellets and enhances the deep-sea deposition rate of zooplankton-derived organic material.

KW - zooplankton

KW - copepod

KW - deep sea

KW - hydrostatic pressure

KW - fecal pellet

KW - carbon

U2 - 10.1093/plankt/fbae002

DO - 10.1093/plankt/fbae002

M3 - Article

SN - 0142-7873

JO - Journal of Plankton Research

JF - Journal of Plankton Research

M1 - fbae002

ER -