Culture of mussels, Mytilus edulis L. is a developing industry in Irish coastal waters. Settling larvae are collected on 10 m long ropes which are suspended from g.r.p. rafts at a density of five ropes per square metre or from paired long lines, buoyed by plastic floats, at a density of some four hundred ropes per hundred metres. Mussels are harvested after eighteen months when the ropes yield up to 5 kg live weight per metre or approximately 250 kg m−2. Commercial culture at this density clearly exerts a considerable effect on energy and nutrient flow in the coastal ecosystem. In order to quantify the role of cultured mussels we investigated the carbon and nitrogen budget for production rafts and long lines in Killary Harbour, a fjordic inlet on the Irish west coast (Rodhouse et al. 1984) and compared these with estimates for the wild population on the shore.
Significance of microheterotrophs in the decomposition of phytoplankton: estimates of carbon and nitrogen flow based on the biomass of plankton communities