Although the most visible effect of fish cage aquaculture is the output of particulate organic waste, 80% of the total nutrient losses from fish farming are plant-available as potentially eutrophicating substances. This project will assess the ability of commercially important seaweeds, cultivated in the immediate vicinity of caged fish, to reduce the impact of such nutrient releases. The algae cultivated in high nutrient sites will be tested as a food source for humans and for cultivated shellfish, and a model of the distribution of dissolved contaminants from sea-cage fish farms will be developed to predict the impact of introducing algal cultivation at any site.