“…Indeed, empirical studies often find that community composition changes significantly along salinity gradients (Martin, ; Gelwick et al ., ; Jaureguizar et al ., ; Fuller, McGhee & Schrader, ). However, these predictions do not necessarily extend to poeciliid fishes, which are considered to be euryhaline (Rosen & Bailey, ), and several species, including P. reticulata , show tolerance to gradual changes in salinity (Gibson & Hirst, ; Zimmerer, ; Shikano & Fujio, ). Thus, the abrupt limit to the distribution of this species at the brackish–freshwater interface was unexpected.…”