Dear colleagues, We are pleased to announce a new publication assessing the aplicability of an innovative methodology to evaluate the ecophysiological condition in marine mammals: Alves F, M Dromby, V Baptista, R Ferreira, AM Correia, M Weyn, R Valente, E Froufe, M Rosso, I Sousa-Pinto, A Dinis, E Dias, MA Teodósio (2020). Ecophysiologicaltraits of highly mobile large marine predators inferred from nucleic acidderived indices. Scientific Reports10, 4752. https://doi.org/10.1038/s41598-020-61769-7 Abstract Nucleic acid-derived indices such as RNA/DNA ratios have been successfully applied as ecophysiological indicators to assess growth, nutritional condition and health status in marine organisms given that they provide a measure of tissue protein reserves, which is known to vary depending on changes in the environment. Yet, the use of these biochemical indices on highly mobile large predators is scarce. In this study, we tested the applicability of using nucleic acids to provide insights on the ecophysiological traits of two marine mammal species (common bottlenose dolphins and short-finned pilot whales) and explored potential related factors (species, sex, season, and residency pattern), using skin tissue (obtained from biopsy darts) of apparently healthy and adult free-ranging animals. Significantly higher RNA/DNA ratios were obtained for bottlenose dolphins (p < 0.001), and for visitor pilot whales when compared with resident pilot whales (p = 0.001). No significant changes were found between the sexes. Based on the percentile approach, the samples contain individuals in a general good condition (as the 10th percentile is not closer to the mean than the 75th percentile), suggesting that the studied region of Macaronesia may be considered an adequate habitat. The combination of this effective tool with genetic sexing and photographic-identification provided an overall picture of ecosystem health, and although with some limitations and still being a first approach, it has the applicability to be used in other top predators and ecosystems. The paper is open access and freely available for download at: https://rdcu.be/b20Ie or contact me at filipe.alves@mare-centre.pt or filalves@rocketmail.com Cheers, Filipe Alves Postdoctoral fellow MARE - Marine and Environmental Sciences Centre / ARDITI Oceanic Observatory of Madeira Caminho da Penteada, Madeira Tecnopolo, 9020-105 Funchal, Portugal +351 291721216