THE FECAL PELLET FRACTION OF OCEANIC PARTICLE FLUX (MARINE GEOLOGY, BIOGEOCHEMISTRY, SEDIMENT TRAP).

摘要

Particle flux research has shown that the mass transport of micron-sized organic and inorganic material to the deep-sea is accomplished via particle aggregates (>63(mu)m). Ubiquitous fecal pellets produced by crustacean zooplankton have been frequently cited as a significant mode of large particle transport in the open-ocean. The objectives of this study are to quantify the mass flux of pelagic zooplankton fecal pellets, determine their contribution to the total biogeochemical fluxes of oceanic particulate matter, and to examine such fluxes as a function of time and depth.; Fecal pellet samples were obtained from five open-ocean stations using moored PARFLUX sediment traps deployed at depths between 389m to 5068m. The sampling sites chosen represented a broad range in surface productivity levels from oligotrophic to eutrophic. The stations were located in the north central Pacific (P(,1)), the western tropical Atlantic (E), the eastern tropical Pacific (CL II), and in the Pacific Panama Basin (PB(,1), PB(,2) sites).; A wide range of fecal pellet mass flux values were obtained, reflecting the varying degrees of primary and secondary productivity at the stations. The pellet mass flux at P(,1) site was 1-2 orders of magnitude less than that measured at the moderately productive E and CL II sites. At the PB sites, the pellet fluxes were 3-7-fold greater than those reported from the E and CL II sites. Upwelling-induced cycles of productivity levels as well as deep-water current activity, had significant effects on the PB pellet fluxes.; The fecal pellet data presented here show that contrary to previous assumptions, these ubiquitous biogenic particles represent less than 5% of the total mass flux of particulate material through the open-ocean. Despite the fact that large numbers of intact pellets are collected at abyssal depths, they contribute an average of only 1-10%, 0.5-4%, 1-3%, and 0.5-4% to the total measured deep-sea fluxes of particulate organic, carbonate, opaline silica, and lithogenic silica material, respectively. However, the pelletal organic carbon may provide up to 66% of the calculated energy requirements of the deep-sea benthos. The absence of pellets from the sites' cores indicates that they are rapidly remineralized at the oxic sediment-water interface.