“…If we consider our findings in the context of the previously proposed “RI” thresholds, the relationship between Ln RR and theoretical p O 2 / p CO 2 ‐ratio obtained supports criticisms of Seibel and Childress (2012) that the thresholds are inadequate and do not fully capture sources of variation in Ln RR observed in this analysis. Although its use has been challenged (Seibel & Childress, 2012), the only experimental tests thus far available involved marine invertebrates from the Chilean coast, Baltic Sea, and Eastern Australia (Fontanini et al., 2018; Steckbauer et al., 2015; Treible et al, 2018). The responses of marine organisms to RI values within the range of 0.7–1.0, which was proposed to delineate the level at which aerobic respiration must be severely compromised (Brewer & Peltzer, 2009), were modest (Ln RR ≈ −0.4, i.e., 33% reduction in performance compared to controls with RI values of 1.5–1.8, Figure 3a).…”