As significant differences between males and females were not observed, individuals of both genders were pooled according to gametogenic stage. Fatty acid profiles of all gametogenic stages observed during the trial are shown in Table 5. One-way ANOSIM for FA signatures of gonads at different maturity stages highlighted a significant difference between stage I and all the other stages for urchins in both treatments, however the only significant difference beyond this point was observed between stage I and stage III in gonads of urchins fed with the Kelp diet. The SIMPER test is of particular interest in this case as it highlighted a continual increment of saturated FA (14:0) as gametogenesis progressed in gonads of urchin fed with Kelp while it did not change significantly in urchins fed with the Pellet diet (Table 5). Interestingly, the FA primarily responsible for the observed differences between maturity stages was not the same in the two treatments: 18:1n − 9 for Kelp diet and18:2n − 6 for Pellet diet. More specifically 18:1n − 9 significantly decreased after stage I in the Kelp treatment whereas it increased in the Pellet treatment, and 18:2n − 6 significantly increased after stage I in the Pellet treatment whereas it did not change in urchins fed with the Kelp treatment.