Search Results (7)

Freshwater ecosystems in Lithuania are threatened by the introduction of invasive fish species including Neogobius fluviatilis, N. melanostomus, Perccottus glenii, and Pseudorasbora parva. Data on helminth parasites of these fishes have not been comprehensively studied, with only two reports on parasites of N. melanostomus from the Curonian Lagoon and Baltic Sea, Lithuania. We examined 278 fish individuals representing 4 invasive species from 13 waterbodies. Using morphological and molecular analyses, we identified 29 helminth taxa representing 15 digenean trematodes, 6 nematodes, 4 cestodes, 2 acanthocephalans, and 2 monogeneans. With 18 species, N. fluviatilis had the highest helminth diversity, followed by N. melanostomus (11 species) and Ps. parva (8 species). Perccottus glenii was found to be free from helminth infection. The availability of historical information on the native fish parasites in Lithuania allowed us to conclude that out of the 29 recorded species, invasive fish serve as hosts for 22 local fish helminth species, while 7 helminth species have been reported exclusively in invasive fish. Based on newly obtained and previously published data, a total of 34 helminth species parasitise invasive fish in Lithuania, of which 30 use these fish as intermediate or paratenic hosts. Full article

The introduction of non-native freshwater fish is a primary cause of aquatic biodiversity loss at global scale. Such introductions have a severe impact on freshwater ecosystems in terms of competition, predation, habitat alteration, genetic pollution and transmission of diseases and parasites. A systematic review was conducted on the helminths parasites of freshwater fish in the context of species introduction and a total of 199 publications were retrieved between 1969 and November 2022. Several scenarios may arise when a new fish species arrive in a recipient area. Non-native fish hosts can co-introduce their parasites without transmitting them to native fish (e.g., the case of North American Centrarchidae and their Monogenea parasites). Another possible outcome is the transfer of these parasites to the native fish fauna (spillover, e.g., the cases of the Nematoda Anguillicola crassus Kuwahara, Niimi & Itagaki, 1974 and the Monogenea Gyrodactylus salaris Malmberg, 1957). Reciprocally, non-native fish hosts may acquire parasites in their new distribution range whether these parasites are native or were previously introduced (e.g., the cases of Ponto-Caspian Gobiidae and the Chinese sleeper Perccottus glenii Dybowski, 1877). Acquired parasites can then be spilled back to the native fauna. This phenomenon is of particular interest when non-native fish hosts influence the dynamics of zoonotic parasites. Full article

Climate change can have a significant impact on the Earth’s ecosystems. Invasive species will respond to climate change, and their responses will have ecological and economic implications. Habitat suitability models (HSMs) are some of the most important tools currently available for assessing the potential impacts of climate change on species. The projections of a model of suitable conditions for three invasive fish species in Europe, Lepomis gibbosus, Perccottus glenii and Pseudorasbora parva, built using Maxent and based on the occurrence throughout the range (native and invasive), on the current climate of Europe and on the forecast climate data for the 2050s and 2070s in the SSP2 and SSP5 scenarios are presented herein. For Lepomis gibbosus and Pseudorasbora parva, climate change will lead to a significant expansion of their zones, with suitable conditions to the north and east, while the change in suitability in their existing ranges will be moderate. For Perccottus glenii, the zone with suitable conditions will shift northward, with a gradual deterioration in the southern and central parts of its current range and an improvement in the northern part. Thus, at present and until the 2070s, Lepomis gibbosus and Pseudorasbora parva can be considered potentially dangerous invasive species in most parts of Europe, while Perccottus glenii can be considered as such only in the northern part of Europe. Full article

Wetlands are of great importance for biodiversity and nature conservation, especially geographically isolated wetlands (GIW). Yet literature about the ecological value of such GIW is missing, especially at the edge of the distribution of endangered species such as amphibians. In 2018 and 2022, we monitored amphibian communities in 15 isolated (GIW) and 12 non-isolated (nGIW) ponds by counting individuals using three methods: (1) capturing with hand nets, (2) visual counting, and (3) capturing with fyke traps. The three methods provided similar results, showing the great importance of GIW for amphibians, especially newts, whose abundance was 5–13 times greater in GIW compared to nGIW. The largest numbers of species and individuals (adults and larvae) were found in isolated wetlands (GIW). In non-isolated water bodies (nGIW) where more than 10 individuals of the Chinese sleeper Perccottus glenii, an alien invasive fish, were found, amphibians were not found at all. Importantly, between 2018 and 2022, the northern crested newt, T. cristatus, dramatically decreased in the nGIW. As a result of our work, it was revealed that the reconstruction of geographically isolated wetlands is very important for the conservation of amphibian biodiversity in a changing climate. One of the most effective measures aimed at protecting amphibians from negative factors—the spread of alien invasive fish species and diseases—is the reconstruction of wetlands in historically exploited landscapes with the creation of a wide range of water bodies yet broadly dominated by geographically isolated ponds. Full article

In the modern world, when the problems of the environment are most acutely associated with climate change, amphibians are considered to be the most vulnerable group of anamniotes as an indicator of the state of wetlands. Along with a decrease of numbers among amphibians in Europe, nowadays newts especially suffer from the impact of invasive species, in particular predators such as the Chinese sleeper, Perccottus glenii. This predatory fish species has recently spread to areas of primary relevance for newt reproduction. This fish consumes eggs, larvae, and even adult newt individuals. Using an ecological niche approach and climate based species distribution models (SDM), we applied the coefficient of determination (R²) for comparing the level of similarity of the built SDM for the newts Triturus cristatus and Lissotriton vulgaris, and the Chinese sleeper. We show that by 2050, the level of climatic niche similarity for these native and invasive species will increase from 12% to 22% throughout Europe, and from 44% to 66% in Eastern Europe. This study highlights the expansion of the Chinese sleeper as a real threat to European biodiversity of wetlands in the near future, especially in their most northeastern distribution range. Full article

This study is devoted to the investigation of Azygia (Digenea: Azygiidae) species diversity using classical morphological, recent molecular tools (28S rRNA and cox1 mtDNA for genetic-based inference) and robust statistical techniques (Principal component analysis, PCA). The analysis revealed that the genus Azygia included four valid species: A. lucii, A. longa, A. hwangtsiyui, and A. sibirica n. sp. The distribution of the type species A. lucii was confirmed in the largest Russian rivers: the Volga and the Ob. The worms isolated from Perccottus glenii were determined as the Chinese species A. hwangtsiyui, according to the genetic data for the cox1 mtDNA gene, at 1.32–1.56%. The new species, Azygia sibirica n. sp, was described from Esox lucius in the Ob River and differentiated from the type species A. lucii by the smaller ovary, testes and prostatic sac, wider body, very narrow pharyngeal lumen and form of anterior margin of ovary. In addition, multivariate analysis and three methods for species delimitation (ABGD, GMYC, bPTP) showed the subdivision of A. lucii and A. sibirica n. sp. into two separate groups, one from the Volga River and another from the Ob River, respectively. To conclude, A. lucii infects Esox lucius in the western (European part of Russia, the Volga River basin), and northern (Western Siberia, the Ob River basin) parts of Russia; A. sibirica n. sp. has also been found to infect Esox lucius in the Ob River, while A. hwangtsiyui infects Perccottus glenii in the South of the Russian Far East (the Artymovka River basin). Full article

The aim of this study was to assess the status of aquatic invasive alien species (IAS) in the shoreline zone of the Bulgarian sector of the Danube River, Danube tributaries, and adjacent standing water bodies in the frame of the Joint Danube Survey 4 (JDS4). Seven benthic macroinvertebrates and seven fish IAS were identified. The crayfish Faxonius limosus was frequently found and abundant in the tributaries. The mussels Corbicula fluminea, Dreissena rostriformis bugensis, and Sinanodonta woodiana dominated in the Danube River and the middle and lower reaches of the tributaries, while the fish Carassius gibelio, Perccottus glenii, and Lepomis gibbosus were most abundant in the standing water bodies. The integrated biocontamination estimated by taxonomic groups (crayfish, molluscs, and fish), sampling methods, and type of water bodies ranged from moderate in the shoreline zone of the Danube River, through moderate to high in the canals and lakes, to severe in the Danube tributaries and the reservoirs. The results demonstrate the importance of IAS in the assessment of the ecological status/potential of the water bodies in the DRB. The comprehensive evaluation of the aquatic IAS pressure will provide valuable information and support for the implementation of the national and EU IAS and water policies in the DRB. Full article