The interactions of mussel aquaculture with physico-chemical properties and the biogenic elemental
composition of the surface sediment were studied at a long-line farm, located in a 12 km2 area, which
included the farm (4 km2) characterized by relevant freshwater inputs along the North-Western Adriatic
coastline. Negative redox potentials were detected at two stations directly affected by the farm. Total
phosphorus content reached the highest concentration at stations located beneath the farm. OC/TP and
TN/TP showed similar patterns, which was characterized by average values underneath the farm
(respectively 45.5 and 4.5) that were significantly lower than those measured at the control stations. Our
hypothesis, that these patterns could be related to organic matter enrichment of the surface sediment
underneath the farm, due to intense mussel biodeposition, was confirmed by the mass accumulation
rates, estimated to be respectively 23, 2.3, 0.94 and 0.26 g m2 y-1 for organic carbon, total nitrogen, total
and organic phosphorus. Data concerning the sediment chemistry were normalized with respect to the
pelite fraction thus increasing the capability of detecting the environmental impact of the farm under
variable background sedimentary fluxes.
