Pelagic zooplankton and fish release faecal material which rapidly sinks through the water column and contributes various amounts and types of organic and other chemical constituents to bottom sediments. The major importance of this process in linking biological events in the water column with inputs to sediments has been well demonstrated in a number of sea areas through the use of field experiments with pumps or traps (Bishop et al. 1977; Gagosian, Volkman & Nigrelli, 1983; Honjo, 1978; Knauer, Martin & Bruland, 1979; Prahl, Bennett & Carpenter, 1980; Wakeham et al. 1980; Wakeham, Farrington & Volkman, 1983). In general, field studies have shown that the deposition of organic matter of pelagic origin occurs with considerable alterations both quantitative and qualitative (Gagosian, Nigrelli & Volkman, 1983; Prahl et al. 1980; Wakeham, 1982). Such studies, however, have not clearly defined how individual biological processes competing in the water column influence the overall composition of organic matter in vertically transported paniculate material.