The contribution of deep-sea macroplankton to organic remineralization: results from sediment trap and zooplankton studies over the Madeira Abyssal Plain

Abstract

At a subtropical deep-sea site of water depth 5440 m the flux of material entering and leaving a 900 m thick stratum 100 m above the seabed was measured using sediment traps. Differences between the organic carbon entering the stratum and that leaving was taken as a measure of the remineralization rate within it. At the same site the biomass of the net zooplankton was measured, and using published estimates of their respiratory requirements, their organic carbon demands were calculated. The results indicate that the zooplankton were responsible for about 9% of the remineralization occurring in that body of water but possibly much higher further up in the water column. The remainder is presumably carried out by those organisms too small, too fragile or too agile to be captured by the net. Although the zooplankton may not contribute greatly to organic carbon remineralization, they are likely to modify sinking and suspended particles in such a way as to have a significant effect on material flux.