The researchers identified 41 different species of tiny animals called zooplankton in the lower Euphrates basin. They found 10 families of Rotifera, 6 families of Cladocera, and 4 families of Copepoda in the area between Birecik Dam Lake and Karkamış Dam Lake. The most species-rich family in Rotifera was Lepadellidae with 4 species, in Cladocera it was Daphnidae with 4 species, and in Copepoda it was Cyclopoidae with 7 species.