The toxicity of Cu in sediments can be mitigated by various sediment fractions (Environment Canada 1998). For example, Malueg et al. (1986) observed higher LC50s for Daphnia magna when peat (i.e., organic matter) was added to the system. Similarly, Austen et al. (1994) observed a higher abundance of nematodes in sediment having high organic matter content when compared to sediments low in organic matter, with similar dosages of Cu. These results suggest that organic matter may decrease the toxicity of Cu to freshwater and marine benthic organisms and 23.4 mg•kg-1 (Phelps et al. 1985