The baseline respiration rate (Time 0) between control and treatment individuals were similar with respiration rates of 1.75±0.12 and 1.46±0.19 μmol O2 g fw−1 h−1, respectively (Fig. 8). Over the 8 d experimental period there was a significant interaction between treatment and time (P=0.043) demonstrating that the respiration rate of R. odorabile was influenced both over time and between treatments ( Table 6). However, the highly significant between-subject effect of treatment ( Table 6) indicates that the significant interaction term was driven primarily by differences in the respiration rate between treatment and control sponges over time. After 24 h of exposure to fine clay sediments the respiration rate of treatment sponges increased by 43% of their baseline respiration rate, and were almost double the rate of respiration of the control sponges ( Fig. 8). These respiration rates remained consistent for up to 2 d of exposure to fine clay sediments and respiration rates remained elevated (up to 1.5 times higher) during the 4 d of exposure. After day 4 the sediment exposure was stopped and both the treatment and control sponges were allowed to recover for 4 d. After 4 d of recovery the respiration rates of the treatment sponges were similar to baseline respiration rates and were also similar to the respiration rate of the control sponges (1.35±0.17 μmol O2g fw−1 h−1) ( Fig. 8).