Development of sediment-quality criteria—A proposal from experimental field-studies of the effects of copper on benthic organisms

Very few of the numerous studies of the effects of copper on animals living in marine sediments have involved manipulative field-experiments. Such experiments provide greater realism than laboratory-based studies in terms of environmental variability or complexity, but the otherwise confounding effects of this variation can be removed by random allocation of treatments to experimental units. We describe an experiment in sandy sediments in Botany Bay, NSW, Australia, in which concentrations of copper in the sediments were manipulated using blocks of plaster impregnated with copper sulphate. Replicate copperenhanced and control treatments were randomly allocated to experimental units. Thus, any differences among treatments in the patterns of change in their faunas can be unambiguously ascribed to the copper treatment. The use of manipulative field-experiments is discussed in the context of the development of sediment-quality criteria.