The eutrophication of coastal waters caused by anthropic activities has become a common problem in many countries. This process contributes to an increase in primary productivity and often generates undesirable changes in the structure and function of aquatic ecosystems. In recent decades, eutrophication caused by intensive aquaculture has become a constant concern for government authorities, owing to the large amount of residues produced by this activity. These wastes (mostly fecal material and uneaten food) increase water nutrients, in particular nitrogen and phosphorous (Beveridge 1996).