The Don River basin is a new stage of expansion of Potamopyrgus jenkinsi (Smith, 1889) (Gastropoda, Hydrobioidea) in Europe

Abstract

The role of invasions has been repeatedly discussed and elucidated in Russian and foreign literature [1‐4]. Problems related to invading species are especially acute in water bodies of arid zones, manly closed water bodies, such as the Caspian Sea, the Sea of Azov, and formerly the Aral Sea. The Sea of Azov and its catchment area are among the most vulnerable ecosystems. This is mainly because the sea is relatively (incompletely) isolated (a continental body of water) and has an unstable hydrological and hydrochemical regimen, which allows invaders with a potentially wide capacity for osmoregulation to adapt. This is entirely true for the catchment areas of the above seas (including the Don, Kuban’, Volga, Ural, Kuma, Syr-Darya, and smaller rivers). These rivers serve as a reserve of the Pontocaspian relict fauna, which is very sensitive to all environmental changes, including invasions. The expansion of invading species may be strikingly rapid. One example is the finding of Potamopyrgus jenkinsi in the Don basin in June and July of 2007. Potamopyrgus Stimson, 1865 was first found in Europe in the late 19th century (the species Potamopyrgus jenkinsi (Smith, 1889) described from the Themes mouth). During the 20th century, Potamopyrgus was found in many regions of Europe. The species composition of the genus Potamopyrgus in the area of invasion is still a matter of discussion. It has been hypothesized that all European Potamopyrgus belong to the same New Zealand species P. antipodarum (Gray, 1843), that there are several species in Europe [5], and that two discrete lineages (clones) have invaded Europe in different periods from different local populations of New Zealand [6, 7]. The existence of a number of European species (probably, pure parthenogenetic strains) of Potamopyrgus differing in ecology and salinity preferences that have no analogues in the New Zealand fauna, as well as some paleontological data, allowed Anistratenko [5] to hypothesize that they are autochthonous in Europe. Anistratenko regards ecologically different strains of Potamopyrgus as separate species P. jenkinsi ; P. alexenkoae Anistratenko in Anistratenko et Stadnichenko, 1995; and P. polistchuki Anistratenko, 1991. Molecular genetic studies on Potamopyrgus from some Western European habitats demonstrated the existence of two strains both genetically and morphologically differing from each other [6, 7]. They are assumed to have invaded from isolated habitats on the North Island of New Zealand in different periods of time. Potamopyrgus may also form new pure strains or species in the area of invasion (saltatory speciation, which is possible for clonal invading species) [8].