The biological pump's efficiency, determined by particle transformations in the euphotic zone and mesopelagic processes, is typically parameterized using the Martin curve. This study uses in situ experiments from C-RESPIRE to measure microbially mediated POC flux attenuation across six oceanic regimes. Microbial degradation comprised 7–29% of flux attenuation, suggesting a more significant zooplankton role. Microbial remineralization varied 20-fold across sites and depths, with lower rates at high POC fluxes. Vertical trends were linked to temperature gradients at low-latitude sites, but other factors influenced mid- and high-latitude sites. This deconstruction of the Martin curve reveals the mechanisms driving microbially mediated POC flux attenuation.

M. Bressac, E. C. Laurenceau-Cornec, F. Kennedy, A. E. Santoro, N. L. Paul, N. Briggs, F. Carvalho, P. W. Boyd