ABSTRACT
The downward ux of particulate organic material is an important process in biogeochemical cycles in the marine environment (Jahnke 1996). Downward uxes of organic particles vary widely in different areas of the world’s oceans, they are largely dependent upon the primary production pulses from the upper layers of the water column, and are typically characterized by strong seasonal uctuations (Honjo 1982; Deuser and Ross 1990). In shallow coastal ecosystems, the export of organic material to the sea oor generally accounts for 30%–50% of the primary productivity of the photic layer, whereas in the open ocean it accounts for 1%–3% (Lampitt and Antia 1997). This “rain” of organic matter supplying the sea oor represents a key process determining the quantity and composition of sedimentary organic matter on the seabed (Danovaro et al. 2003; Dell’Anno et al. 2005) and is one of the major factors controlling the distribution, dynamics, and metabolism of the benthos (Graf 1989; Pfannkuche 1993; Danovaro et al. 1999a; Smith and Kaufmann 1999).
