“…early life history stages, Gammarus salinus, Gammarus tigrinus, growth rate, hatching success, juveniles, non-indigenous species, Pontogammarus maeoticus, salinity tolerance Although salinity tolerance has been studied for different species globally (e.g., Dobrzycka-Krahel & Graca, 2018;Ellis & MacIsaac, 2009;Kobak et al, 2017;McFarland, Baker, Baker, Rybovich, & Volety, 2015;Ovčarenko, Audzijonyte, & Gasinjnaite, 2006;Paiva et al, 2018), it remains unclear how offspring would respond to those salinities. In this study, we extend the comparative salinity assessment of Paiva et al (2018) by evaluating not only adults, but also juveniles of one Northern European (Gammarus salinus), one Ponto-Caspian (Pontogammarus maeoticus) and one North American species (Gammarus tigrinus) to determine whether adults and juveniles would reveal the same salinity pattern (Figure 1).…”