Copper concentrations for the four treatments are shown in Table 3.1. The ANZECC level was based on the current recommended water quality trigger value for 95% species protection (ANZECC 2000). The ‘Field’ concentration was based on the maximum dissolved copper concentration measured from 29 seawater samples collected across four sites in the Wellington region between September 2011 and January 2012 (Appendix A). The ‘High’ level was chosen as a realistic level occurring in moderately polluted water such as near large cities (Table 1.1). Metal stock solutions were made from reagent grade copper sulphate (CuSO4.5H2O). Actual copper concentrations were determined by recreating experimental conditions without urchin larvae in January 2013 using the same protocol, culture medium, glassware and stock solution as during the actual experiment. Water samples were analysed by Environmental Laboratory Services, Lower Hutt.
Table 3.1: Copper concentration chosen in larval assays. Measured dissolved concentrations were filtered through a 0.45 μm mesh and send to ELS.