Prediction of benthic impact for salmon net-pens based on the balance of benthic oxygen supply and demand

Abstract

The ratio between oxygen supply and oxygen demand was examined as a predictor of benthic response to organic enrichment caused by salmon net-pen aquaculture. Oxygen supply to the benthos was calculated based on Fickian diffusion and near-bottom flow velocities. A strong linear correlation was found between measured carbon sedimentation rates and rates of benthic metabolism. This relationship allowed an estimation of oxygen demand based on sedimentation rates. Comparison of several production sites in Maine (USA) coastal waters showed that for sites where oxygen demand exceeded supply benth~c impacts were high and for sltes where oxygen supply exceeded demand benthic impacts were low These findings wrl-e s~~mmanzed In the form of a predict~ve model that should be useful in siting salmon production fac~litles