Particulate Matter Distributions, Chemistry and Flux in the Panama Basin: Response to Environmental Forcing

J. K. B. Bishop, J. C. Stepien and P. H. Wiebe

Progress in Oceanography V17, 1-59, 1987


Multidisciplinary studies of the particle cycle were carried out during two cruises in July-August and November-December 1979 at 5N 82W in the Panama Basin as part of the Sediment Trap Intercomparison Experiment (STIE) and Composition, Flux and Transfer Experiments (C-FATE). Measure- ments included: primary production; new production; hydrography; nutrient distributions; 12-kHz echo sounding; macrozooplankton biomass and group abundances; microzooplankton group abundances; vertical distributions, chemistry, and morphology of suspended and sinking particulate matter; and vertical particulate matter fluxes.

Comparisons were made among particle fluxes determined by several means. Size distributions of fecal matter and fecal pellets determined on samples from the Large Volume in - situ Filtration System (LVFS) were used in settling models to calculate vertical particle fluxes. These results were compared with fluxes estimated from measurements of new production, with fluxes determined by short-term deployments of sediment traps in the upper 300m, and with fluxes recorded by moored time-series traps at 1268m.

Previous C-FATE results had shown that the rates of primary production and new production are determined by the physical and chemical environment of the euphotic zone at this location. Results presented here indicate that new production and particle flux are in balance in the euphotic zone on the time scale of days. The data also demonstrate that particulate matter distributions, chemistry and fluxes in the water column extending from the euphotic zone to lO00m are closely related to rates of primary production and new production in the euphoric zone. Finally, the data show that the vertical particle flux gradient in the upper lO00m is determined by the instantaneous distributions, feeding activities, and migratory behaviour of zooplankton and fish present in the water column.

Figure 17: showing vertical profiles of POC flux and Zooplankton Biomass Particulate Organic Carbon flux (nmol C per square meter per day). Zooplankton Biomass (umol C per cubic meter). The gradient of vertical POC flux was strongly related to Zooplankton biomass distribution.

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