Impacts of biodeposits from suspended mussel (Mytilus edulis L.) culture on the surrounding surficial sediments

The effects of increased sedimentation on the macrobenthic community physical structure, and biogeochemistry of the surficial sediment around two farms in southwest Ireland were examined in conjunction with current characteristics. Both farms had been in production for over eight years, were of reasonably large size (> 100 MT) and located in low-energy environments. At one site, the benthic community was subjected to bulk sedimentation and organic enrichment and reduced macrobenthic infaunal diversity and elevated levels of organic carbon were recorded close to the farm. In general, effects were restricted to a radius of 40 m around the farm. Conversely. at the second sits, there were no observed effects of mussel biodeposits on the benthos and a diverse macrobenthic community persisted. We propose that variations in the dispersion of biodeposits caused by local current patterns had a significant influence on the impact observed, and that this could also account for differences reported in other studies. (C) 2001 International Council for the Exploration of the Sea.