BLUE MUSSEL SEA FARMING – EFFECTS ON WATER QUALITY
Water currents through a blue-mussel culture have been studied together with inorganic nutrients, oxygen, salinity and temperature. A hanging long-line culture of Mytilus edulis L. was followed from June 1978 to March 1980. There were considerable changes in all parameters during the farming period. These changes were to some extent attributable to the seasonal cycle. However, still greater and more rapid changes in concentrations of the nutrients were caused by changes of the water masses in the area. The conclusions are that in this case the mussel culture did not give rise to any measurable effects on the water quality in the area with respect to inorganic nutrients and oxygen. Nevertheless, special sections through the culture showed that nutrient excretion from the mussels could be measured in situ on some occasions, especially by warm water and low current velocity. On these occasions the concentration of ammonium-nitrogen was doubled and the concentration of phosphate-phosphorus was quadrupled in the water mass that passed through the culture. “Complete abstract not presented.”