Influence of suspended mussel lines on the biogeochemical fluxes in adjacent water in the Iles-de-la-Madeleine (Quebec, Canada)

Oxygen consumption and nutrient fluxes were measured in 80 L enclosures containing water, 1- or 2-year-old mussels, or 1- or 2-year-old line sections (mussels plus associated fauna - organic matter complex: AFOM) in August and September 2003 in the Iles-de-la-Madeleine. Mussel lines acted as nutrient sources and oxygen sinks in adjacent water. The magnitude of fluxes at the mussel line interface depended on the nutrient (NH4 >> Si(OH)(4), PO4 > NO3 > NO2). Mussel metabolism contributed greatly to O-2 consumption and NH4 and PO4 releases. Mussel influence was greater in stressful periods. The AFOM complex mainly contributed to NO3, NO2, and Si(OH)(4) fluxes. These fluxes could originate from organic matter decomposition rather than from associated faunal metabolism. The influence of AFOM depended on its composition and thus on line immersion time. Mussel lines by ammonia releases could be a factor of reduction of N limitation in the water column. Mussel line should be integrated as a new interface of biogeochemical exchanges in environmental carrying capacity studies.