Distribution and Current Status of Stone Crayfish Populations Austropotamobius Torrentium (Decapoda
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Zoogeography and Faunistics ACTA ZOOLOGICA BULGARICA Research Article Acta zool. bulg., 66 (2), 2014: 181-202 Distribution and Current Status of Stone Crayfish Popula- tions Austropotamobius torrentium (Decapoda: Astacidae) in Natura 2000 Protected Areas in Bulgaria Milcho Todorov1, Vera Antonova1, Zdravko Hubenov2, Mila Ihtimanska1, Lubomir Kenderov3, Teodora Trichkova1, Emilia Varadinova1, Christo Deltshev1 1 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences; 2 Gagarin Str., Sofia 1113, Bulgaria; Email: [email protected] 2 National Museum of Natural History, Bulgarian Academy of Sciences; 1 Tsar Osvoboditel Blvd., Sofia 1000, Bulgaria 3 Faculty of Biology, University of Sofia; 8 Dragan Tsankov Blvd., Sofia 1164, Bulgaria Abstract: The stone crayfishAustropotamobius torrentium is one of the three native crayfish species occuring in Bul- garia (the other two are Astacus astacus and Astacus leptodactylus), which is protected by many European and national laws. In comparison with other European countries little is known about the population status of stone crayfish in Bulgaria. The aim of this work was to summarise newly collected data on the distribu- tion and population status of A. torrentium in Natura 2000 protected areas in Bulgaria. This study was car- ried out from September 2011 to November 2012. During this period 994 localities in 570 different rivers and streams from 76 Natura 2000 protected areas were studied. A total of 2340 individuals were found in 112 localities from 83 rivers and streams in 30 protected areas. Stone crayfish had comparatively restricted and uneven distribution in Bulgaria and its populations were characterised by a relatively low abundance (0.002 – 0.34 ind./m2). The species was found in the range from 189 m to 1342 m a.s.l., but it was mainly located from 300 to 900 m (78.5% of all localities). There was a clear trend for the distribution of species in high mountains, where it was wider distributed in southern slopes and did not occur or was rare in northern slopes. Stone crayfish was found mainly in rivers with banks covered by beech (Fagus sylvatica), alder (Alnus glutinosa), oak (Quercus spp.) or sycamore (Platanus orientalis), and rarely in rivers with banks covered only by bushes. The species was almost completely absent in the exposed areas of the rivers and in the areas with coniferous vegetation. All our findings can be used as a basis for future monitoring of the state of stone crayfish populations and assessing the conservation status of the species in Bulgaria. Keywords: Crayfish, Astacidae, Austropotamobius torrentium, distribution, Natura 2000, threats, conservation Introduction Crayfish (Decapoda: Astacidae) are some of the larg- stone crayfish,Austropotamobius torrentium (Schrank, est invertebrates that play an important role in fresh- 1803) (MACHINO , HOLDICH 2006, PÖCKL et al. 2006, water ecosystems. At present around 600 species are SOUTY -GRO ss ET et al. 2006, HOLDICH et al. 2009). In found worldwide, many of them in North America and the middle of the 19th century, as a result of the im- Australia. Only five native crayfish species occur in ports of non-indigenous crayfish species from North Europe: noble crayfish, Astacus astacus (Linnaeus, America, ‘crayfish plague’ (caused by the oomycete, 1758), narrow-clawed crayfish, Astacus leptodactylus Aphanomyces astaci Schikora, 1906) was imported in Eschscholtz, 1823, thick-clawed crayfish, Astacus Europe. This dangerous virulent disease on crayfish pachypus Rathke, 1837, white-clawed crayfish, was first established in Italy, in 1859. It was widespread Austropotamobius pallipes (Lereboullet, 1858), and in almost all European countries by the mid- to late 20th 181 Todorov M., V. Antonova, Z. Hubenov, M. Ihtimanska, L. Kenderov, T. Trichkova, E. Varadinova, C. Deltshev century. These uncontrollable outbreaks together with Material and Methods the increasing human impact led to considerable de- cline in the stocks of the native crayfish species in most From September 2011 till November 2012 we stud- European countries. In order to relieve the huge dam- ied 994 localities (transects) in 570 different rivers age and for aquacultural purposes, various non-indige- and streams from 76 Natura 2000 protected areas in nous crayfish species (NICS) were introduced in many Bulgaria. The sampling sites were located in the three of these countries. Of the ten NICS introduced at least main water drainage basins in Bulgaria (the Danube nine have become established in the wild in Europe River, Black Sea and Aegean Sea). The sampling and their number varies in different countries. Western localities are presented with the names of the riv- and Central European countries have the most of the ers, geographical names, altitude and sampling dates introduced alien species (Netherland – 6, England – 6, (Appendix 1). In addition, geographical coordinates Germany – 5, France – 5, Italy – 5, Austria – 3, Spain and information about the abundance of crayfish are – 3, and Switzerland – 3). Many of the Southeastern given for the localities where the species was found European countries, together with Andora, Estonia, (Table 1). All the localities of A. torrentium in the Irish Republic, Liechtenstein, Moldova and Ukraine, Natura 2000 network of protected areas in Bulgaria have not introduced any crayfish species yet (SOUTY - are given in Fig. 1. GRO ss ET et al. 2006, PÖCKL et al. 2006, HOLDICH et al. Crayfish were captured using standard methods 2009). (e.g. MACHINO , FÜREDER 2005) – by hand searching Bulgaria is one of the European countries where both during the day and at night, by trapping and by only native species are found so far. There are three electrofishing. In each locality we studied transect crayfish species in the country: noble crayfish, A. with length of 100 m and a width of 1 m (area of 2 2 astacus, narrow-clawed crayfish, A. leptodactylus, 100 m ) to establish crayfish abundance (ind./m ). and stone crayfish, A. torrentium. BUL G URKOV Once crayfish were identified and counted, they (1964) reported Astacus pachypus Rathke, 1837, in were released back at the same places where they Bulgaria but this was based only on one specimen. were caught. A list of all studied Natura 2000 pro- Subsequently, several studies were carried out in the tected areas and sampling localities is presented in country, but the existence of that species was not Appendix 1. confirmed. Therefore, we consider that this species is not present in the country. For a long period of time from the mid- to late Results 20th century the stone crayfish in Bulgaria was stud- A total of 2340 individuals of A. torrentium were ied only a few times and these studies concerned found in 112 localities out of 83 rivers and streams mainly its biology and distribution in the country from 30 protected areas (Table 1, Fig. 2). Localities (BUL G URKOV 1961, SU B CHEV , STANI M IROVA 1986, belonging to the Aegean Sea basin (78) showed clear 1998). Since the beginning of this century the study- predominance over the localities belonging to the ing of A. torrentium has intensified and now there is Danube River basin (26) and to the Black Sea basin more new information about its distribution and size, (8). Most of the localities in the Aegean Sea basin structure and state of different populations of the spe- where A. torrentium was found are in the mountains cies in Bulgaria (ZAIKOV , HU B ENOVA 2007, ZAIKOV et Pirin, Belasitsa, Central Balkan, Western Rhodopes, al. 2010, 2011, STOYNOV et al. 2013, TRICHKOVA et Konyavska, Osogovo and Vitosha (the Struma, al. 2013). Some studies on the reproductive biol- Mesta and Maritsa river basins). Almost all locali- ogy of stone crayfish in two different biotopes have ties in the Danube River basin are predominantly in been carried out, and the results are important for the the West and Central Balkan Mountains (the Iskar future conservation measures and restocking of the and Yantra river basins). The only localities of the species (HU B ENOVA et al. 2010). Nevertheless, the species in the Black Sea basin are in the upper reach- information on the population status of A. torrentium es of the Luda Kamchiya River and the Golyama in Bulgaria is still relatively limited. Kamchiya River, and their tributaries in Kotlenska The aim of this work is to summarise the newly Mountain (East Balkan Mountains). Stone crayfish collected data on the distribution and population sta- was found neither in the Danubian Plain, Black Sea tus of stone crayfish in Natura 2000 protected areas coast, Strandzha and Sakar Mountains, nor in the in Bulgaria. All our findings can be used as a basis Eastern and Central Rhodopes Mountains. for future monitoring of the state of stone crayfish The most abundant populations of A. torren- populations and assessing the conservation status of tium were established in the protected areas Rodopi- the species in Bulgaria.