Effects of a floating fish farm in Kiel Fjord on the sediment

The effects of a floating fish farm in Kiel Fjord, Western Baltic, have been studied in the summer 1991 by underwater video, sediment and benthos samples. Significant alterations of the benthos and sediment geochemistry as compared to control stations were documented. The sediment under the farm is anoxic, organically enriched (1.5 to 3.5 fold), covered by sulfur bacteria, and almost free of benthic macro fauna. Rates of decay of organic carbon and oxygen uptake (derived from porewater profiles) are high and account for 100–150 mmol m-² d-¹ in summer.