On the distribution and general abundance of non-native species associated with the Ebro River (Castejón, Navarra, Ne Spain)

Abstract

Fifteen exotic aquatic and semi aquatic Non-native Invasive Species (NIS) plus another thirteen exotic species (herbs and trees) were detected in a meandering stretch of 8.5 km and in an agricultural waterway and pools complex in Castejon (Ebro River floodplain, Navarra, NE Spain). The zebra mussel was the most ubiquitous NIS in all types of aquatic natural habitats and human infrastructures, followed by the Asian clam and red swamp crayfish in the river, both with established and abundant populations. The presence of false map terrapins is recorded for the first time in the Ebro River, and the presence of the benthic diatom throughout this stretch is confirmed, although no massive crusty filaments were found. The artificial riverside harbours with hybrid poplars could be a shelter for a small population of the beaver that was re-introduced by unapproved means in the 2000’s.