First record ofOrconectes limosus (Rafinesque, 1817) in Bulgaria

The spiny-cheek crayfish Orconectes limosus (Rafinesque, 1817) was found for the first time in Bulgaria. Fourteen specimens were caught with a hand-net for 1.5 hours in the Topolovets River, tributary of the Danube River, near the town of Vidin (N 43.941306; E 22.838611), on 17.06.2015.

The spiny-cheek crayfish originates from North America. In Europe, the species was first introduced into Germany in 1890 and have since spread to at least 22 European countries (Holdich et al. 2009, Kouba et al. 2014, Kozák et al. 2015). In the Danube River basin, the species has been reported from Germany and Austria (Nesemann et al. 1995), Hungary (Thuranszky, Forro 1987, Puky et al. 2005, Puky, Schád 2006, Puky 2014), Serbia (Karaman, Machino 2004, Pavlović et al. 2006, Simić et al. 2008), Slovakia (Janský, Kautman 2007, Puky 2009, Lipták 2013), Croatia (Maguire, Klobučar 2003, Maguire et al. 2011), and Romania (Pârvulescu et al. 2009, 2012). The spiny-cheek crayfish has occurred in the main Danube channel (Lipták, Vitázková 2014), as well as in the Danube tributaries and adjacent water basins, e.g. the Tisza River (Sallai, Puky 2008), the Drava River (Hudina et al. 2009), and the Tamiš River (Lipták et al. 2013).

Spiny-cheek crayfish are a small to medium sized crayfish species, the largest specimens reaching just over 11cm long. They have distinctive spiny cheeks, legs with orange tips bordered by a dark band and striped abdomens.They are characterised by high fecundity, rapid maturation and reproduction. Spiny-cheek crayfish are found in rivers, wide steams, ponds and lakes, and prefer calm and turbid waters to fast flowing. Adults are tolerant of low temperatures, dry conditions,soft substrates, muddywaters, as well as water pollution (Kozák et al. 2015). In the Danube River catchment, the species was detected to cross on land from one water body into another (Puky 2014).

Spiny-cheek crayfish have been reported to decrease the indigenous crayfish populations in Europe through competition for resources and by acting as a vector for crayfish plague. In Croatia the rapid spread of O. limosus through the Danube River catchment has adverse effects on the populations of A. leptodactylus (Faller et al. 2009). In the Romanian sector of the Danube River, from 2009 to 2011, the relative abundances of O. limosus steadily increased, while the native A. leptodactylus dramatically decreased in abundance. Currently, 70-90% of A. leptodactylus have been replaced by O. limosus. The presence of A. astaci DNA was detected in at least 32% of the invasive and 41% of the native crayfish coexisting in the Danube River (Pârvulescu et al. 2012).

Acknowledgements:
The study has been supported by the Financial Mechanism of the European Economic Area 2009-2014, Project ESENIAS-TOOLS, Д-33-51/30.06.2015, and within bilateral cooperation project between Bulgarian Academy of Sciences and the Academy of Sciences of the Czech Republic.

Contact persons:
TeodoraTrichkova, IBER-BAS, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Milcho Todorov, IBER-BAS, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Zdravko Hubenov, NMNH-BAS, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Pavel Jurajda, IVB, This e-mail address is being protected from spambots. You need JavaScript enabled to view it