Theodoxus fluviatilis’ re-establishment in the River Rhine: a native relict or a cryptic invader?
The endangered freshwater snail Theodoxus fluviatilis is a widely distributed European member of the gastropod family Neritidae. This taxon was abundantly found in the River Rhine until the end of the 20th century, and was considered to be extinct there since the late 1990s. Since 2006, a new, but morphological different form of T. fluviatilis has been recorded in the Upper Rhine region. Our aim was to identify the source of the recent populations by analysing individuals from five sites throughout the current known distribution along the River Rhine. Therefore, we sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene, and compared the data with those from individuals collected in the early 1990s and 40 already known haplotypes from a pan-European study. Our results show that all studied recent Rhine individuals harbour only one COI haplotype that corresponds to an already known haplotype described from the River Danube and the Ukraine region near the Black Sea. This suggests that a re-colonisation of the River Rhine by T. fluviatilis from the River Danube is the most likely scenario of the re-establishment of the species. This route of invasion is known for other freshwater taxa that originate from the Ponto-Caspian region. Even though the current Rhine populations belong to T. fluviatilis their invasion may have consequences for the native Central European populations. Therefore, we recommend considering the current Rhine population as ‘cryptic invader’.
KeywordsInvasion mtDNA COI Main-Danube canal Neritidae
We sincerely thank G. Becker, C. Hellman and U. Mürle for providing specimen from the River Rhine.
- Hirschfelder H-J, Salewski V, Nerb W, Korb J (2011) Schnelle Ausbreitung einer Schwarzmeerform der Gemeinen Kahnschnecke Theodoxus fluviatilis (LINNAEUS 1758) in der bayerischen Donau. Mitt dtsch malakozool Ges 85:1–10Google Scholar
- Lucey J, McGarrigle ML, Clabby KJ (1992) The distribution of Theodoxus fluviatilis (L) in Ireland. J Chonchol 34:91–101Google Scholar
- Meinert W, Kinzelbach R (1985) Die limnischen Schnecken und die Muscheln von Rheinland-Pfalz (Mollusca: Gastropoda et Bivalvia). Mainzer Naturwiss Arch Beiheft 4:58 pp+mapsGoogle Scholar
- Nesemann H (1993) Die rezenten Arten der Gattung Theodoxus Montfort 1810, im ungarischen Tiefland, ein Beitrag zur Zoogeographie der danubischen Süßwassertierwelt. Club Conchylia Inf 25:67–78Google Scholar
- R Development Core Team (2011) R: a language and environment for statistical computing, vol htttp://www.R-project.com. R Foundation for Statistical Computing, Vienna, Austria
- Schöll F, Tittizer T (1988) Wiederauftreten größerer Populationen von Theodoxus fluviatilis (Linné 1758) am Mittelrhein. Mitt Dtsch Malakolzool Ges 43:35–36Google Scholar
- Schultz H, Schultz O (2001) Erstnachweis der Gemeinen Kahnschnecke, Theodoxus fluviatilis (Linnaeus, 1758) in Österreich (Gastropoda: neritidae). Ann Naturhist Mus Wien 103B:231–241Google Scholar
- Westermann F, Schöll F, Stock A (2007) Rediscovery of the river nerite Theodoxus fluviatilis in the German Upper Rhine. Lauterbornia 59:67–72Google Scholar
- Yildirim MZ (1999) The Prosobranchia (Gastropoda: Mollusca) species of Turkey and their zoogeographic distribution: 1. Fresh and brackish water. Turk Zool Derg 23:877–900Google Scholar
- Zettler MA (2008) Taxonomy and distribution of the genus Theodoxus Montfort, 1810 in Germany. Presentation of historical and recent data including a bibliography. Mollusca 26:13–72Google Scholar