Abstract
Since 1987, 20 years of investigations on the river Meurthe from its springs to its confluence with the river Moselle have revealed at least 43 species of Ephemeroptera, i.e. almost two-thirds of the regional diversity. The typical assemblages occurring in upper and middle courses are described; these parts of the river can be considered as “reference streams” for the region, the rest of the river being more degraded by human activities. The upper rhithral section pertains to the Vosges Mountain, and has escaped the acidification which affects many surface waters in this crystalline massif. The middle course is a typical epipotamal section on silicious alluvions. The most remarkable species found in the upper course are Ameletus inopinatus, Baetis alpinus, B. melanonyx, Rhithrogena gr [hercynia], Rh. cf carpatoalpina, Ephemerella mucronata. In the middle course Baetis liebenauae, Baetis vardarensis, Caenis lactea, Ephemera lineata, Heptagenia coerulans, H. fuscogrisea, H. longicauda, Rhithrogena beskidensis were found. Both upper and middle sections are partly included in the “Natura 2000” European network.