Metal stock solutions were made from reagent grade copper sulphate (CuSO4.5H2O).Concentrations given are nominal concentrations, but actual dissolved copper concentrations in treatments were measured in January 2013 using the same experimental conditions without urchin larvae as described in section 3.2.2 (Table4.2). The ANZECC level was based on the current recommended water quality trigger value for 95% species protection (ANZECC 2000). The High level was chosen as a realistic level occurring in moderately polluted water, such as near large cities (Table 1.1).