Vertical profiles of settling particles in the water column.

During 16 months of deployment, 239 g m−2 dry matter settled in the 40-m trap, with an average flux of 14.9 g m−2 month−1 (Table 2 and Fig. 2). The content of organic carbon was 21.9% at that depth and that of total nitrogen 1.6% (Table 2 and Fig. 2). The resulting atomic C/N ratio of 15 indicated that the sedimented material resulted from the autochthonous production by suspended phytoplankton and that terrigenous input is likely to be negligible at that site. The amount of pigments gathered during the 16 months deployment in the 40-m trap was 193.1 μmol m−2 for chlorophyll a and 797 μmol m−2 for chlorophyllide a+pheopigment a. The average flux was hence 61.8 μmol m−2 month−1 settled chlorophyll a+chlorophyllide a+pheopigment a (Table 1). It is worth noting that the replicate samples of the 40-m trap deviated strongly (coefficient of variation: 60.5%), whereas the coefficients of variation for the replicate samples in the traps