Dear colleagues, We are happy to sharethe publication of our paper: Insights into the trophic ecology of white-beaked dolphins /Lagenorhynchus albirostris/ and harbour porpoises /Phocoena phocoena/ in Iceland Filipa I. P. Samarra, Asunción Borrell, Anna Selbmann, Sverrir D. Halldórson, Christophe Pampoulie, Valérie Chosson, Thorvaldur Gunnlaugsson, Guðjón M. Sigurðsson, Alex Aguilar, Gísli A. Víkingsson MEPS 702: 139-152 The article can be accessed at https://www.int-res.com/abstracts/meps/v702/p139-152/ <https://www.int-res.com/abstracts/meps/v702/p139-152/>or you can contact me directly for a PDF of the paper (fipsamarra@gmail.com) Abstract Sympatric organisms can avoid competition by occupying different ecological niches, a mechanism known as niche partitioning. In Iceland, white-beaked dolphins /Lagenorhynchus albirostris/ and harbour porpoises /Phocoena phocoena/ are the most common small cetaceans observed but their trophic ecology remains understudied, including the potential for resource competition. In this study, we measured δ^15 N and δ^13 C values from white-beaked dolphin (n = 28) and harbour porpoise (n = 29) muscle samples collected over a 33 yr period (1987-2019) to compare isotopic niche width and overlap of both species, as well as diet composition. We also tested for within-species effects of sex, age class, body length, year of sampling and origin (bycatch vs. stranding) on the δ^13 C and δ^15 N values. Intra-species variations included differences between stranded and bycaught white-beaked dolphins and ontogenetic variations in both species, but further studies are necessary to investigate the factors that might explain these results. Inter-species comparisons showed that harbour porpoises and white-beaked dolphins had non-overlapping isotopic niches, with harbour porpoises exhibiting smaller niche widths (corrected standard ellipse area, SEA_c : 1.25 vs. 2.13‰^2 ). While white-beaked dolphins had a broader diet, composed primarily of gadoids but with contributions of other fish species, harbour porpoises fed almost exclusively on capelin /Mallotus villosus/, suggesting niche segregation and width is largely maintained by targeting different prey resources. Both species also showed no long-term changes in trophic ecology, despite recent ecosystem changes in this region, possibly a result of adapting to spatial changes in prey distribution or shifts to other prey at similar trophic levels. This article is dedicated to the memory of our co-author, colleague and friend Dr. Gísli Víkingsson, who was instrumental in developing cetacean research in Iceland. Bestregards, Filipa Samarra -- Filipa Samarra ResearchSpecialist/Sérfræðingur University of Iceland's Institute of Research Centres/Stofnun rannsóknasetra Háskóla Íslands Ægisgata 2 900 Vestmannaeyjar, Iceland ORCID: https://orcid.org/0000-0002-9909-0565 ResearchGate: https://www.researchgate.net/profile/Filipa_Samarra Follow us on Facebook and Instagram @icelandic.orcas www.icelandic-orcas.com