After the construction of the Volga Hydroelectric Station and other dams, migration routes of the Caspian lamprey were obstructed. The ecological niches vacated by this species attracted another lamprey of the genus Lampetra to the Upper Volga, which probably came from the Baltic Sea via the system of shipways developed in the 18 th and 19 th centuries. Based on collected samples and observations from sites in the Upper Volga basin, we provide diagnostic characters of adults, and information on spawning behavior. Silver coloration of Lampetra fluviatilis was noted for the first time and a new size-related subsample of “large” specimens was delimited, in addition to the previously described “dwarf”, “small” and “common” adult resident sizes categories. The three water systems: the Vyshnii Volochek, the Tikhvin and the Mariinskaya, are possible invasion pathways, based on the migration capabilities of the lampreys. Dispersal and colonization of the Caspian basin was likely a combination of upstream and downstreams migrations. First, the lampreys migrated upstream along the rivers of the Baltic basin until they reached the water-parting line, followed by mostly downstream dispersal into rivers of the Caspian basin. Dispersal in the Volga River was similar, in accordance with the migration cycle of this opportunistic lamprey species.
Представлена дополненная информация о распространении и условиях обитания речной миноги (Lampetra fluviatilis L.) на территории Тверской области. Ареал на территории области представляет собой сочетание исторического (водотоки бассейна Балтийского моря) и инвазионного (водотоки бассейна Каспийского моря) компонентов. Обоснована идея вселения миноги в систему р. Волга по системам искусственных судоходных каналов. Состояние популяций в Каспийском бассейне указывает на продолжающийся процесс освоения новых местообитаний. Additional information on the distribution and habitat of the European river lamprey (Lampetra fluviatilis L.) in the Tver Region is presented. The areal of the European river lamprey in the Region consists of the historical (watercourses of the Baltic Sea Basin) and invasive (watercourses of the Caspian Sea Basin) components. The idea of the lamprey invasion in the Volga River through the system of manmade shipping canals is substantiated. The condition of the lamprey’s populations in the Caspian Sea Basin indicates the ongoing process of the species expansion.
The extended freshwater life of Petromyzontiformes larvae (ammocoetes) takes place mainly in lotic waters where it has been studied in detail. Information on ammocoetes in lentic habitats is extremely limited, with few data on the occurrence of specimens in ponds or large lakes. The area of the Smolenskoye Poozerye National Park has a dense network of lakes and rivers, with streams abundantly populated by lamprey larvae of the genera Lampetra and Eudontomyzon. In this paper, we evaluate the habitability of lakes belonging to such systems and the manner in which they are populated by lamprey. Larval habitat identification and documentation (bed analysis where ammocoetes exist, including ground composition and biotic and abiotic habitat characteristics) were carried out, resulting in the first documentation of larvae and metamorphic specimens of Eudontomyzon sp. inhabiting littoral areas of small lakes. These specimens were found in the fringe biotopes between the river mouth and lakes. One peculiarity that distinguishes the lentic habitats from the typical river ones is the absence of distinct currents. Freshwater flows diffusely into lakes, mixing continuously at the sites we studied. Preferred habitats for Eudontomyzon sp. consisted of swales filled with debris carried from inflowing streams and deposited as current diminished. In ammocoete beds of this type, the examined larvae had a good trophic position. Such habitats can be both permanent and ephemeral as tributary water levels changes. During flood events, elevated velocity can flush debris and ammocoetes away from these fringe habitats and further into a lake. No accentuated active decomposition was found in the areas where the ammocoetes were present. The results of the study indicate that Petromyzontiformes larvae may be more common in lentic habitats than is currently documented.
The European river lamprey came to the Upper Volga from the Baltic Sea most probably via a system of shipways developed in the 18th and 19th centuries. The Vyshnii Volochek, Tikhvin, and Mariinskaya water systems are possible invasion pathways for this species. Dispersal and colonization of the Caspian Basin was likely a combination of upstream and downstream migrations. Analysis of museum and our own samples showed that lamprey possibly migrated upstream (for spawning) along rivers of the Baltic Basin until they reached the watershed boundary from which they could disperse downstream (in the juvenile period) into rivers of the Caspian Basin. Dispersal in the Volga River could occur in accordance with the migration cycle of this opportunistic lamprey species and lead to the present distribution. Key features (dentition and number of trunk myomeres) showed that lamprey from the studied area are similar to lampreys from the Baltic basin, although specimens in each population have their own peculiarities in morphology (size and coloration). Genetic data (Cyt-b) support the idea of a relatively recent invasion of lamprey into the Upper Volga. The haplotype, found in three rivers, is one of the most widespread in Europe and is found along the supposed route of invasion.
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