Aquatic Invasions (2007) Volume 2, Issue 1: 45-54 Open Access doi: http://dx.doi.org/10.3391/ai.2007.2.1.5 © 2007 The Author(s). Journal compilation © 2007 REABIC Research Article Distribution of the alien freshwater snail Ferrissia fragilis (Tryon, 1863) (Gastropoda: Planorbidae) in the Czech Republic Luboš Beran1* and Michal Horsák2 1Kokořínsko Protected Landscape Area Administration, Česká 149, CZ–276 01 Mělník, Czech Republic 2Institute of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, CZ–611 37 Brno, Czech Republic E-mail: [email protected] (LB), [email protected] (MH) *Corresponding author Received: 22 November 2006 / Accepted: 17 January 2007 Abstract We summarize and analyze all known records of the freshwater snail, Ferrissia fragilis (Tryon, 1863) in the Czech Republic. In 1942 this species was found in the Czech Republic for the first time and a total of 155 species records were obtained by the end of 2005. Based on distribution data, we observed the gradual expansion of this gastropod not only in the Elbe Lowland, where its occurrence is concentrated, but also in other regions of the Czech Republic particularly between 2001 and 2005. Information on habitat, altitude and co-occurrence with other molluscs are presented. Key words: alien species, Czech Republic, distribution, Ferrissia fragilis, habitats Introduction used for all specimens of the genus Ferrissia found in the Czech Republic. Probably only one species of the genus Ferrissia Records of the genus Ferrissia exist from all (Walker, 1903) occurs in Europe. Different Czech neighbouring countries (Frank et al. 1990, theories exist, about whether it is an indigenous Lisický 1991, Frank 1995, Strzelec and Lewin and overlooked taxon or rather a recently 1996, Glöer and Meier-Brook 2003) and also introduced species in Europe (Falkner and from other European countries, e.g. Great Britain Proschwitz 1995). This gastropod was most often (Kerney 1999), Sweden (Falkner and Proschwitz named as Ferrissia wautieri (Mirolli, 1960) and 1995), and France (Falkner et al. 2001). it was considered as native or cryptogenic, requiring further studies (Glöer 2002, Glöer and Zettler 2004). When referred to as Ferrissia Material and methods clessiniana (Jickeli, 1882) it was considered as a non-native mollusk in Europe (Falkner and The datasets used are from senior author's Proschwitz 1995). New studies (Walther et al. database of over 40,000 records of aquatic 2006) confirmed that the North American molluscs, most of which were obtained by field ancylid Ferrissia fragilis (Tryon, 1863) is a research during the previous 10 years. The cryptic invader of European and East Asian remainder come from Czech museum collections freshwater ecosystems. The name F. fragilis is and published papers. 45 L. Beran and M. Horsák Results and discussion Distribution in the Czech Republic In the Czech Republic this snail was recorded for the first time in 1942 from pools near Sadská and for the second time in 1946 from an oxbow lake of the Elbe River near Mělník (Ložek 1971) (Record No. 85 respectively No. 27 in Annex 1, see also Figure 2, A). It is probable that this species was subsequently overlooked because further records were not made until 1975 (Elbe River oxbow lake, near Ostrá, V. Ložek pers. comm.) and 1978 (Ohře River oxbow lake, near Doksany, Flasar 1998) (Figure 2, B). Between 1991 and 2000 the species was recorded at 45 new sites (Figure 2, C). Data obtained until 2001 are summarised in Beran (2002). A rapid increase in records was observed between 2001 and 2005 when 106 finds were recorded (Figure Figure 1. Shell of Ferrissia fragilis (record No.123 in Annex 1). Photo by M. Horsák. 2, D). This increase was also visible in Figure 3 where the number of records of F. fragilis is weighted by all records of other freshwater molluscs in particular period (data from senior The main sampling method for aquatic author's database were used). The data molluscs was to wash vegetation or sediments represented 0.05 % from 1901-1950, 0.03 % using a metal sieve (kitchen strainer, diameter 20 from 1951-1990, 0.34 % from 1991-2000 (Beran cm, mesh size 0.5-1 mm). This was combined 2002), and 0.88 % from 2001-2005. The sites with a search of various substrates present; identified for this snail are concentrated in the stone, wood and artificial surfaces (e.g. plastic Elbe Lowland, but between 2001 and 2005 this bags and bottles). This method is only qualitative species was recorded more and more frequently - time and area under study was different. All in other regions of the Czech Republic as well molluscs present in samples were identified. (Figure 2). Thus, it is evident that the distri- Specimens of Ferrissia fragilis (Figure 1) and bution of this snail is increasing and is spreading most of the other molluscs were identified based despite the possibility that the species was on shell morphology. When this identification overlooked in the past but at least sampling method was not possible, some species (i.e. effort in 1991-2000 was similar to that in 2001- Stagnicola, Gyraulus) had to be dissected and 2005. Such a noticeable increase in records is then identified using their copulatory organs. more typical for non-native invasive species e. g. The classification used follows Beran (2002). Potamopyrgus antipodarum (Gray, 1843), Altogether, 155 records of F. fragilis were Menetus dilatatus (Gould, 1841), Corbicula obtained; 109 of these included extra environ- fluminea (O. F. Müller, 1774) or Dreissena mental data and were used for an analysis of polymorpha (Pallas, 1771) than for native habitat preferences and co-occurrence with other species (reviewed in Beran 2002 or Meier-Brook species. The assemblage of the whole site was 2002). taken into account for the analysis of co- This species has also been recorded in Czech occurrence, not only the species recorded in the Republic greenhouses (Horsák et al. 2004) from site's part where F. fragilis occurred because where it could spread outside, but greenhouse these more detailed data was not at disposal. sites are not included in this paper. 46 Distribution of Ferrissia fragilis in Czech Republic Figure 3. Relative number of records of Ferrissia fragilis . Figure 4. Habitats with occurrence of Ferrissia fragilis. BroCan – brooks, canals; Rivers – rivers; OxbLak – oxbow lakes, pools; WatRes – water reservoirs, ponds; WatBod – water bodies created during mineral extraction (mainly sandpits). Habitats In all cases this snail was recorded from perma- nent water bodies; this was in common with Polish records from Bernard (1994) and Strzelec and Lewin (1996). Stagnant waters were a more frequently recorded habitat of this snail than flowing waters. Records from lotic habitats were mainly concentrated in the Elbe River, especially in the stretches upstream of weirs. In fact these stretches had reduced flow due to channelization during weir construction. The most frequently observed habitats were oxbow lakes, pools mostly in floodplains and also water bodies created during mineral extraction (mainly sand- pits). Less frequent habitats included water Figure 2. Distribution of Ferrissia fragilis in the Czech reservoirs. Only occasionally this snail was re- Republic till 1950 (A), till 1990 (B), till 2000 (C) and till corded in rivers and brooks or canals (Figure 4). 2005 (D). 47 L. Beran and M. Horsák the Czech Republic where sites with altitude below 150 m are restricted. In comparison to previous results of Beran (2002), more data on occurrence at higher altitudes now exist and 552 m is the highest altitude record for this species. Co-occurrence of other molluscs In the studied water-bodies F. fragilis co- occurred with 53 molluscs. The most species- rich site harboured 23 species. In the median site, 10 species were found co-existing with F. fragilis. In 50% of the sites researched, F. fragilis co-occurred with 7-15 species (Figure Figure 5. Number of records of Ferrissia fragilis in particular 6). The frequencies of co-occurrence of altitude ranges. particular species with Ferrissia fragilis varied considerably. Radix auricularia (Linnaeus, 1758), Gyraulus albus (O. F. Müller, 1774), Bithynia tentaculata (Linnaeus, 1758), Hippeutis complanatus (Linnaeus, 1758), Anodonta anatina (Linnaeus, 1758) co-occurred with F. fragilis in more than half of the 109 studied sites (Annex 2). These mollusc species are common and widespread in the Czech Republic (Beran 2002). On the other hand, co-occurrences with Viviparus viviparus (Linnaeus, 1758), Valvata macrostoma Mörch, 1864, Anisus spirorbis (Linnaeus, 1758) and Corbicula fluminea were documented in one case only. Acknowledgements Figure 6. Number of molluscs species at particular sites. We would like to express our thanks to Nicole Cernohorsky for language comments and Frances Lucy for comments which improved the manuscript. The manuscript preparation was partially supported by the long-term research plans of Masaryk University (Czech Ministry of Education, MSM In terms of substrates, Ferrissia fragilis was 0021622416). usually found on the surface of emergent macrophytes (e.g. reedmace Typha spp., reed References sweet grass Glyceria spp.); macrophytes with large floating leaves (e.g. the water lilies Beran L (2002) Vodní měkkýši České republiky – rozšíření a jeho změny, stanoviště, šíření, ohrožení a ochrana, Nymphaea spp.and Nuphar lutea); different man- červený seznam (Aquatic molluscs of the Czech Republic made objects (waste, e.g. plastic and glass – distribution and its changes, habitats, dispersal, threat bottles or jars); wood; dead parts of plants and protection, Red List). Sborník přírodovědného klubu (especially leaves), and also stones. v Uh. Hradišti, Supplementum 10, 258 pp Bernard R (1994) New localities of freshwater limpet Ferrissia wautieri (Mirolli, 1960) (Gastropoda: Altitude Basommatophora: Ancylidae) in Poland. Mitt. dtsch. malakozool. Ges. 53: 19-21 Altitude was available for nearly all the datasets Falkner G, Proschwitz T (1995) A record of Ferrissia on F.