Dear colleagues, We are pleased to announce our recent article published on-line (first) in the journal *Ecological Indicators*: *The first confirmed decline of a delphinid population from Brazilian waters: 2000-2015 abundance of Sotalia guianensis in Guanabara Bay, South-eastern Brazil. *Alexandre F. Azevedo, Rafael R. Carvalh, Maja Kajin, Monique Van Sluys, Tatiana L. Bisi, Haydée A. Cunha, José Lailson-Brito Jr. DOI: 10.1016/j.ecolind.2017.03.045 <http://doi.org/10.1016/j.ecolind.2017.03.045> *Abstract*: The abundance of Guiana dolphins (*Sotalia guianensis*) in Guanabara Bay, Rio de Janeiro, South-eastern Brazil, was investigated during the period 2000 – 2015 using mark-recapture models applied to photo-identification data. A combination of Pradel’s model and Pollock’s robust design was applied to estimate abundance and other population parameters, such as apparent survival (Φ), capture probability (p) and seniority probability (γ). Total population size was estimated by correcting the estimates derived from the Pradel robust design model for the proportion of marked individuals in the population. The corrected abundance estimates decreased drastically (37%) between 2000 (62, 95% CI 59-65) and 2015 (39, 95% CI 37-40), and can be explained by a combination of low survival and recruitment rates. Determining the ultimate causes for the decline in this Guiana dolphin population is difficult, but the likely reasons are of anthropogenic nature, such as by-catch, habitat degradation, intense traffic of vessels and exposure to immunosuppressive and endocrine-disrupting pollutants. We provide the first quantitative evidence of population decline in a delphinid from Brazilian waters. Conservation and management actions are urged to change this scenario. Other local dolphin populations in Brazil, which are exposed to the same impacts, may also be currently declining or are expected to do so in the near future. For this reason, we emphasize that anthropogenic impacts upon estuarine/coastal species that exhibit site fidelity warrant greater attention, because such impacts may lead to the same negative scenario observed in Guanabara Bay. Article available at: https://authors.elsevier.com/a/1Ur3a,XRNLVD2C Best Regards, Alexandre -- Dr. Alexandre de Freitas Azevedo Laboratório de Mamíferos Aquáticos e Bioindicadores - MAQUA Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro Rua São Francisco Xavier, 524 sala 4002E Maracanã, Rio de Janeiro, 20550-013, RJ, Brasil azevedo.alex@uerj.br 55 21 2334-0065 - 2334-0795 55 21 99742-4993 CV: http://lattes.cnpq.br/5095457245652366