Chondrostoma toxostoma

The Ebro catchment has the highest richness of autochthonous limnetic species in the Iberian Peninsula [51]. Salaria (blennius) fluviatilis, is common at the main channel and tributaries, and Chondrostoma toxostoma only occurs at the tributaries. Leuciscus cephalus is a fish of narrow distribution, found only at the Ebro river basin and other small catchments of NE Spain. Salmonids are common at the headwaters one species is native Salmo trutta and two introduced others, Salmo gairdneri and Salvelinus fontinalis. Part of the autocthonous species are endemic, for example the cyprinids Barbus graellsii and Barbus haasi, the cobitid C. calderoni with scattered and scarce populations [52] and A. iberus. 

Barbel Barbus graellsii bBleak Alburnus alburnus Southwestern nase Chondrostoma toxostoma dCarp Cyprinus carpio... 

Different sampling campaigns were carried out from 2002 to 2005. Surface sediments (0-2 cm) were collected at each selected site. Attempts were made to collect several fish from the same locations as the sediment samples. Different fish species were sampled barbels Barbus graellsii), bleaks Alburnus, albumus), south-western nases (Chondrostoma toxostoma) and carps Cyprinius carpio). The whole fish was analysed for bleaks and south-western nases, whereas muscle and liver tissues were analysed for barbels and carps. 

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