Introduction The eastern Mediterranean is sensitive to alien invasions due to its geographic position (i.e., its connection with Atlantic Ocean, Black Sea, and Erythrean regions), crowded maritime traffic, fisheries, and tourism activities in the coastal regions (Galil and Zenotos, 2002). Alien species increased after the opening of the Suez Canal in 1869 and construction of the Aswan Dam (Galil, 2000); hundreds of alien species passed through the Suez Canal to the Mediterranean Sea, forming thriving populations along the Levantine coast (Galil and Zenetos, 2002). To our knowledge, an average of 821 alien species have been reported in the Mediterranean Sea, of which approximately 75% were established in these ecosystems (Zenetos et al., 2017). The species belonging to Oithonidae are widely distributed in different ecosystems and are the most successful free-living cyclopoids in the marine ecosystems (Uye and Sano, 1998). This family is one of the most abundant taxa in estuarine, coastal, and oceanic regions (Paffenhöfer, 1993; Gallienne and Robins, 2001). The importance of the small copepods, such as Oithona, has been recently recognized in pelagic ecosystems (Gallienne and Robins, 2001). Moreover, Oithonidae species are important contributors to ecosystems of the