Dear All We are pleased to share our new open-access publication, where we use high-resolution dive data from beaked whales (Ziphius cavirostris) to model blood and tissue O₂ and CO₂ dynamics. Beyond advancing our understanding of diving physiology, this work provides a mechanistic link between individual metabolic limits and broader conservation frameworks such as Population Consequences of Disturbance (PCoD). Our results show that Ziphius often exceed their calculated aerobic limits and rely on anaerobic metabolism, meaning that even subtle disturbances, such as sonar exposure or altered recovery patterns, can push animals beyond physiological thresholds, with potential fitness costs that accumulate at the population level. By integrating physiology with behavioral and ecological models, this approach offers a more powerful tool for predicting the impacts of disturbance and cumulative stressors on deep-diving cetaceans. The abstract and a link to the article are provided below. If you experience any difficulty accessing the paper, please do not hesitate to contact me at afahlman@whoi.edu. Title: Modelling the effect of varying metabolic rate and cardiac output on estimated tissue and bloodO2 and CO2 levels in an extreme deep-diver, the goose-beaked whale (Ziphius cavirostris) Authors: Andreas Fahlman, A. Schorr, G.S., Sweeney, D.A., Rone, B.K., Coates, S.N., Allen, A.S., Martín López, L.M., Jarvis, S.M., Falcone, E.A. Journal: Experimental Physiology doi: http://doi.org/10.1113/EP093021 Abstract: High-resolution movement data from Cuvier’s beaked, or goose-beaked whale (Ziphius cavirostris, hereafter Ziphius, n = 8) tag deployments (4.1–19.2 days) were used to estimate blood and tissue O2 and CO2 levels. Acceleration and magnetometry data were used to estimate the locomotion cost (LC) from the relationship between activity and the O2 consumption rate. We estimated that the diving metabolic rate (DMR) decreased with increasing dive duration, ranging from 6.18 mL O2 min−1 kg−1 for very short dives (<1.0 min) to 1.65 mL O2 min−1 kg−1 and 2.06 mL O2 min−1 kg−1 for intermediate (>17.5 and ≤33.3 min) and long dives (>33.3min), respectively. The calculated aerobic dive limit (cADL), average behavioural ADL (bADL) and dynamic ADL (dADL) were 62.4, 61.3 (44.3–75.4) and 41.7 (2.0–102.5) min, respectively. Despite the physiological and metabolic adjustments assumed by the model, the muscle O2 ran out for many of the stereotypical long, deep dives exhibited by these animals. Based on the model results, we speculate that a large portion of the foraging dives in Ziphius are fuelled by alternative metabolic pathways, for example, phosphocreatine or glycolysis. A reliance on these alternative metabolic pathways during foraging may require long recovery periods, including primarily aerobic dives. Disturbing this normal dive pattern may disrupt this normal dive pattern, leading to behavioural and physiological changes that could cause trauma.