A sediment trap experiment was carried out in the Bay of Calvi (Corsica, France) over a Posidonia oceanica seagrass bed, at a depth of 36 m. The traps collected 44 samples over a complete annual cycle and allowed a rough partition between 'sinking' and 'resuspended' matter. The measured annual flux of particulate matter amounted to 1.3 kg m-2, of which about 70% arose from sediment resuspension, this process being particularly enhanced during northerly gales. Resuspended material consisted mainly of seagrass-derived detritus, as evidenced by SEM photomicrographs. Chemical analyses of trapped material showed seasonal variations in inorganic carbon content, organic C/N ratio and delta13C. Benthic signature (Cinorg-, Corg- and 13C-enriched Posidonia-derived matter) was emphasized when resuspension occurred, while planktonic features (N- and 12C-enriched matter) prevailed during bloom conditions.
Suspended matter . Seagrass . Detritus . Plankton . Sediment trap
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