Odonatological survey on the river Someş/Szamos in Romania

Species richness of dragonfly fauna provide important information about the water quality of a wetland, since dragonfly nymphs can be considered as indicator organisms of natural waters sensitive to water pollution. In August 1996 an expedition was organised by the Tisza Klub of Szolnok and the Pro Európa Liga of Tárgu Mure? to get information about the ecological conditions of the Some?/Szamos. As a part of this expedition an odonatological survey was carried out in the river with the aim of revealing its dragonfly fauna and these results are summarised in this paper. There were no literature found referring to the Odonata fauna of the Rumanian section of the river. In the Hungarian section of the Some? Ambrush et al. (1995, 1998) collected 7 species as nymphs and 7 species as adults altogether. In their papers the larval occurrence of 4 riverine dragonfly (Gomphidae) species is mentioned, in addition these 4 species occur together in some points of the river. Dévai et al. (1993) collected only 3 frequent species as imagoes near the Some? also in Hungary