Thermohaline conditions and high prey abundance may favor establishment of M. leidyi in the northern Adriatic Sea; however, the concomitant presence of two species of Beroidae, which prey on M. leidyi, may prevent its explosive growth as has been observed in other new localities. Beroe ovata may not establish because salinity in the area may be too high and because it may compete with two native Beroe species for prey