Current limitations of the stone crayfish distribution in Romania: Implications for its conservation status

The stone crayfish Austropotamobius torrentium is one of three indigenous crayfish species in Romania. Extensive research to assess the conservation status of this highly protected species is overdue in this country. Presently, the populations are concentrated in two distinct regions, the southwest and northwest of the country. Most populations were found living in habitats with little anthropic impact. Using logistic and negative binomial regression models, we determined the ecological preferences of the species. The most favourable conditions suggest an equilibrium between the availability of dissolved oxygen, moderate river velocity, and low concentration of organic pollutants. Due to these ecological requirements, the species is generally restricted to sub-montane areas (around 500 m a.s.l.) leading to a high degree of population fragmentation. The spectrum of limitations is completed by invasive species and the crayfish plague agent Aphanomyces astaci. Contact with non-indigenous Orconectes limosus and the crayfish plague is a real threat, especially to the populations inhabiting the order I tributaries of the Danube, in southwestern Romania. We recommend that the Romanian stone crayfish A. torrentium be taken into consideration as an “endangered species”.