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One of the most abundant fish species, Rutilus rutilus, is widely distributed in Lithuania and its potential to adapt to environmental changes attracted our interest. Unfortunately, it is not properly understood how anthropogenic activities can affect the genetic diversity within this species. We studied three populations of roaches (samples collected in the Neris and Žeimena rivers, and Lake Drūkšiai) over a period of five years (from 2017 to 2022) to determine genetic diversity using mtDNA D-loop and ATP6 genetic markers. Genetic diversity parameters, AMOVA analysis, haplotype network, and PCoA analysis revealed a greater genetic variability in roach samples collected in 2017, and the greatest differences were noticed in the population inhabiting Lake Drūkšiai, as compared with other samples studied over a five-year period. Differences in genetic diversity detected after a five-year period led us to the assumption that roach populations may be related to the effects of natural (changing climatic conditions) and anthropogenic (operating nuclear power plant) origin. [ABSTRACT FROM AUTHOR]

Simple Summary: This study concerns evaluation of the possible negative effects of power plants as one of the most important objects generating environmental pollution in aquatic ecosystems. We attempted to research the intraspecific genetic diversity of a naturally distributed fish species, Eurasian perch, based on a comparison of its mitochondrial DNA sequences. To distinguish naturally occurring mutagenesis from DNA changes caused by thermal or chemical pollution, the molecular data representing patterns of perch populations inhabiting hydro-systems profoundly affected by power plants and non-affected perch populations were collected and analysed. The obtained results indicate that most genetic differences among perch populations representing a large geographic area that encompasses territories from the Baltic Sea to Ukraine could be explained by historical and ongoing natural processes instead of pollution from power plants. The intraspecific genetic diversity of freshwater fish inhabiting hydro-systems of the macrogeographic area spreading from the Black to Baltic Seas requires comprehensive investigation from fundamental and practical perspectives. The current study focused on the involvement of the mtDNA ATP6 region in the adaptability and microevolution of Perca fluviatilis within phylogeographic and anthropogenic contexts. We sequenced a 627 bp fragment encompassing the ATP6 region and used it for genetic analysis of 193 perch caught in Latvia, Lithuania, Belarus, and Ukraine, representing natural and anthropogenically impacted populations. We evaluated patterns of intraspecific genetic diversity in the ATP6 region and phylogeographic trends within the studied area compared with previously established D-loop trends. Evaluation of ATP6 coding sequence variability revealed that among 13 newly detected haplotypes, only two were caused by non-synonymous substitutions of amino acids of the protein. PCoA revealed three genetic groups (I–III) based on the ATP6 region that encompassed four previously described genetic groups established based on the mtDNA D-loop. The two mtDNA regions (D-loop and ATP6) have microevolved at least partially independently. Prolonged anthropogenic impacts may generate new point mutations at the ATP6 locus, but this phenomenon could be mainly concealed by natural selection and reparation processes. [ABSTRACT FROM AUTHOR]

Following their first appearance, the invasive fishes Pseudorasbora parva and Perccottus glenii have been in Lithuania for several decades. However, until recently, information relating to their distribution and secondary spread was limited. For this reason, suitable habitats for these fish species were surveyed for their presence across the entire country. Additionally, all previously reported records on the presence of these species were summarized. Results revealed P. glenii to be widely distributed within the country with abundant populations in habitats suitable for the species. The recent distribution of P. parva is restricted to only a few water bodies. It was shown that both species are associated with human mediated transfer, while no natural dispersal of these invasive species was observed. The results of this study suggest that the invasion of Lithuanian inland waters by P. parva and P. glenii is still ongoing, and their occurrence in numerous water bodies, which are still devoid of these species, now seems probable. Demonstrated vectors of P. parva and P. glenii introductions in Lithuania highlight the importance of controlling and screening human activities related to aquaculture, recreational angling and the ornamental fish trade in order to restrict further P. glenii and P. parva expansion in this region. [ABSTRACT FROM AUTHOR]

Based on the original research data of 2018–2019, ten species of aphid parasitoids of the genus Pauesia (Hymenoptera: Braconidae: Aphidiinae) reared from 14 out of 27 available Eulachnini species (Hemiptera: Aphididae: Lachninae) are listed for Lithuanian fauna, seven species being recorded for the first time. No parasitoids were found in colonies of aphid genus Eulachnus, despite having inspected 24 colonies of four species of this genus. Parasitoids for aphid species Cinara (Cinara) hyperophila and C. (C.) piniphila were recorded for the first time. New parasitoid species were recorded for aphid host species C. (C.) brauni, C. (C.) neubergi, C. (C.) pinea, C. (C.) pini, and C. (C.) pruinosa. Summarized information on the distribution and host specificity of Pauesia species in Lithuania is presented. Partial sequences of the mitochondrial cytochrome c oxidase subunit 1 (COI) for 98 parasitoid individuals were analyzed. DNA-based species delimitation by means of Automatic Barcode Gap Discovery (ABGD), generalised mixed Yule-coalescent (GMYC) model, Poisson tree processes (PTP) model, and statistical parsimony network analysis (TCS) gave number of candidate species ranging from 11 to 15. The values of match ratio for each method were from 0.67 for PTP to 0.93 for GMYC. Maximum Likelihood, Maximum Parsimony, and Bayesian Inference analyses confirmed the paraphyly of the parasitoid subgenus Paraphidius. Sequence divergences (p-distances, %) between the parasitoid species Pauesia jezoensis, P. pinicollis, P. cupressobii, and P. goidanichi were on the intraspecific level (0.62–1.14%). Molecular delimitation methods indicate possible existence of three species new to science. [ABSTRACT FROM AUTHOR]

Partial sequences of COI and EF-1α of nine aphid species of the family Adelgidae and partial sequences of 16S rRNA of their endosymbiotic bacteria were used to reveal co-evolutionary relationships between endosymbiotic bacteria and their aphid hosts in Lithuania. In addition to currently recognized taxa of gamma- and beta-proteobacterial endosymbionts ("Candidatus Vallotia", "Candidatus Profftia", "Candidatus Annandia", "Candidatus Hartigia", "Candidatus Ecksteinia", "Candidatus Steffania" and "Candidatus Gillettellia") of Adelgidae, new gamma-proteobacterial (Sodalis-allied) endosymbionts were detected in Adelges (Aphrastasia) pectinatae and Pineus cembrae. Cophylogenetic analyses based on aphid partial COI and EF-1α sequences and 16S rRNA gene fragment of their endosymbiotic bacteriae showed reliable cophylogenetic events confirming the importance of host aphid species relatedness in structuring symbiont communities of adelgid aphid species. Molecular aphid species delimitation analyses based on Bayesian phylogenies of aphid COI and EF-1α and bacterial 16S rRNA fragments indicate adelgid species complexes Adelges (Adelges) laricis - Adelges (Adelges) tardus, Adelges (Gilleteella) cooleyi - Adelges (Gilleteella) coweni, Adelges (Dreyfusia) nordmannianae - Adelges (Dreyfusia) piceae, Adelges (Sacchiphantes) abietis - Adelges (Sacchiphantes) viridis and Pineus pini - Pineus orientalis representing single species each. [ABSTRACT FROM AUTHOR]

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947–2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947–1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4–13.6 pMC during the first 15 years of plant operation. However, during the 2000–2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000–2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment. [ABSTRACT FROM AUTHOR]

Based on the original research of 2017–2018, also reference data, four aphid species and five species complexes of the family Adelgidae listed for Lithuanian fauna. Pineus (Pineus) strobi (Hartig, 1839) is a new species for the fauna of Lithuania. Summarized information on the distribution and host specificity of adelgid species in Lithuania is presented. The most common species recorded from all geographical regions of Lithuania were the ones belonging to the species complexes Adelges laricis – A. tardus, Pineus orientalis – P. pini, Sacchiphantes viridis – S. abietis and Gilletteella cooleyi – G. coweni. Six species of Adelgidae inhabit host plants of the genus Picea, three live on Larix, three – on Pinus, two – on Abies, one – on Pseudotsuga. Partial sequences of mitochondrial (COI) and nuclear (EF-1α) DNA of Lithuanian samples were analysed in comparison with available data from GeneBank representing samples from Central Europe. Pairwise distances of COI and EF-1α fragments between samples belonging to species complexes Adelges laricis – A. tardus, Dreyfusia nordmannianae – D. piceae, Sacchiphantes viridis – S. abietis, Gilletteella cooleyi – G. coweni and Pineus orientalis – P. pini suggest each species complex being a single species. [ABSTRACT FROM AUTHOR]

Ovipara and winged male of Cinara (Cinara) piniphila (Ratzeburg) are described for the first time based on material from Lithuania. Sampling data and morphometric data are given for every morph together with information on partial sequences of mitochondrial COI. Phenological and bio-ecological data of monitored C. (C.) piniphila colonies are reported and discussed. [ABSTRACT FROM AUTHOR]

The European pond turtle, Emys orbicularis, is a critically endangered species in most European countries. Habitat degradation and fragmentation are considered the main reasons for the decline of E. orbicularis. However, the spread of invasive species may also contribute to the disappearance of E. orbicularis populations. We examined the range overlap and predator-prey interactions between the invasive Chinese sleeper, Perccottus glenii, and E. orbicularis through controlled experiments and in field studies. Field surveys showed that both species occupied similar habitats. Predator-prey experiments suggested that newly hatched turtles are resistant to P. glenii predation. Conversely, adults of E. orbicularis consumed juvenile P. glenii even when other food sources were available. Overall, these findings suggested that E. orbicularis is not among the potential prey organisms in the diet of the invasive P. glenii, and that this fish does not directly contribute to the decline of E. orbicularis in Europe. [ABSTRACT FROM AUTHOR]

Introduced species interact both directly and indirectly with native species. Of particular interest from the fisheries management point of view is how the invasive New Zealand mud snail, Potamopyrgus antipodarum, can alter the diet of fish and crayfish. If the snail is somewhat resistant to predation, it cannot be easily included into predators' diet. We examine the direct interactions between the introduced P. antipodarum and benthivorous predators local to temperate lakes through laboratory experiments and field surveys. Field survey showed that P. antipodarum dominated in the macroinvertebrate communities of the studied lakes. Feeding experiments indicated low consumption of P. antipodarum by most of its potential predators. Field diet survey showed that the main fish species did not significantly consume P. antipodarum. Moreover, it was ascertained that this snail can survive passing through the gastrointestinal tract of most studied fish species. Consequently, as local fish do not consume P. antipodarum, a part of lake primary production becomes locked in lower trophic levels. Therefore, there is a legitimate concern that the invasion of this snail may reduce the direct flow of primary production towards higher trophic levels in temperate lakes. [ABSTRACT FROM AUTHOR]

A comparison of the plum aphid (Hemiptera: Aphididae) guild structure in Lithuania before (1975) and after (2012) the establishment of the invasive aphid species Brachycaudus divaricatae Shaposhnikov, 1956, was performed to investigate the impact of this invasive species on the native species complex. No substantial changes in the native plum aphid species composition, host plant associations and seasonal frequency dynamics were detected. The incorporation of B. divaricatae into the plum aphid guild in the eastern Baltic region of Europe was found to have increased the stability of the guild. Such an effect is explainable by the diversification of the guild structure (one more species incorporated in the food chain) and increased effectiveness of the use of resources (cherry plum was underexploited before the invasion of the new aphid species). [ABSTRACT FROM AUTHOR]

We present a comprehensive overview of distribution data of non-indigenous mollusc species in Lithuanian inland waters. The data are based on our own observations obtained during 2007-2013 as well as on published and unpublished records from the last 80 years. Four nonindigenous species have been reported to occur in Lithuanian freshwaters: Dreissena polymorpha, Lithoglyphus naticoides, Potamopyrgus antipodarum and Physella acuta. The last species, however, has not been found in Lithuania since the 1950s. D. polymorpha is the most widespread non-indigenous mollusc species in Lithuania. It was observed in 159 out of 226 investigated localities. The other species are less common. L. naticoides was recorded in 43 sites, whereas P. antipodarum was found in 35 localities. In addition to the possible reappearance of P. acuta, four more mollusc species which are currently absent from Lithuanian freshwaters have been reported as non-indigenous from neighbouring countries and thus might potentially invade Lithuanian inland waters in the future. [ABSTRACT FROM AUTHOR]

In this overview, we consider the rationale and practice of invertebrate introductions into Lithuanian waters, the current distribution of introduced species, test the theoretical expectations of introduction of peracaridan species into lakes, and summarize the large-scale consequences of these translocations. After some early attempts to transfer locally available species within the country, peracaridan species from the Ponto-Caspian region were introduced into Lithuanian waters during the 1960s ( Pontogammarus robustoides, Obesogammarus crassus, Chaetogammarus warpachowskyi, Paramysis lacustris, Limnomysis benedeni and Hemimysis anomala). After their establishment at the site of first introduction in a newly constructed water reservoir on the Nemunas River, further deliberate introductions into Lithuanian lakes and water reservoirs, as well as into more distant areas, were undertaken. These introduced species soon contributed to fish diet and a subsequent increase in the production of commercially important fish was envisaged. However, our collation of available data does not support the enhancement of fish production in Lithuanian lakes. Although perch (selected as a model fish species) assimilated the introduced species into diet and sometimes in large quantities, there was no subsequent influence on somatic growth rates when compared with perch from lakes devoid of alien peracaridans. Comparisons of littoral fish communities of different lakes, and commercial catches in the lake with the most numerous populations of introduced species also indicate no significant effect on fish production. Negative consequences of introduction are more than obvious in contrast. To date, most of the introduced Ponto-Caspian amphipod and mysid species occur in different sites of the Baltic Sea basin outside Lithuania, and their further dispersal may be expected. These species, especially amphipods, have proved to be highly ecologically aggressive, inducing change in resident macroinvertebrate communities and causing increase of biological contamination (i.e. detract from naturalness). Thus, the introduction of alien fodder species was ill advised from an economic, and even adverse from an environmental perspective. [ABSTRACT FROM AUTHOR]

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Biodiversity studies are not only listings of species in local, regional and worldwide faunas and floras. Infraspecific variation might appear an even more exciting field for biodiversity studies. It is common knowledge that species (especially those prospering ones) have large distribution areas. Individuals, demes and populations commonly inhabit distribution areas of their own species unevenly. Remarkable variation of environmental conditions is usually present inside these distribution areas, causing specific trends of adaptive evolution inside the same species, resulting in fixation of locally specific character states, and enforcing designation of various infraspecific units (biotypes, ecotypes, races, subspecies etc.) inside the species. Therefore, detailed ecological, morphological and molecular studies of local populations seem to be urgent for a better understanding of biodiversity and natural management. All this knowledge is summarized by systematics, and might also result in a critical revision of the taxonomic status of a species under analysis. The above statements are illustrated by an example of aphid biodiversity and systematics studies in Lithuania. [ABSTRACT FROM AUTHOR]

Aquatic ecosystems are particularly vulnerable to anthropogenic activity and climate change. The changes in flow regimes in Lithuanian lowland rivers due to the operation of hydropower plants (HPPs) and the impact of altered flow on some fish species have already been studied. The impact of climate change on future natural river runoff and the structure of fish assemblages was also investigated. However, it is still unknown how the combined effect of climate change and flow regulation related to hydropower generation may affect fish assemblages in the downstream river reaches below the Lithuanian HPPs. In this study, the physical habitat modelling system MesoHABSIM was used to simulate spatial and temporal changes in aquatic habitats availability for different fish species under the influence of HPP at different climate change scenarios. Changes in the available habitat were assessed for common fish species in four HPP-affected rivers representing different hydrological regions of Lithuania. The modelling results showed that the operation of HPP under climate change conditions in most rivers could be beneficial for small benthic fish species such as gudgeon Gobio gobio and stone loach Barbatula barbatula. Meanwhile, for larger fish species (e.g., chub Squalius cephalus and vimba Vimba vimba) the alteration in the temporal availability of suitable habitat was relatively higher. [ABSTRACT FROM AUTHOR]

Based on research carried out from 2016 to 2018 there are twenty-six species of aphids of the tribe Eulachnini in Lithuania. Seventeen are members of the subgenus Cinara of the genus Cinara, three of the subgenus Cupressobium and two of the subgenus Schizolachnus. In addition, there are four species of the genus Eulachnus. Summarized information on the distribution and host specificity of Eulachnini in Lithuania is presented. Nine species were in all climatic regions of Lithuania: C. (Cinara) brauni, C. (Cinara) hyperophila, C. (Cinara) neubergi, C. (Cinara) piceicola, C. (Cinara) pinea, C. (Cinara) pini, C. (Cinara) pruinosa, C. (Cupressobium) cupressi and C. (Cupressobium) juniperi. Five species of Lithuanian Eulachnini inhabit host plants of the genus Picea, three live on Larix, thirteen on Pinus, one on Abies, one on Thuja and three on Juniperus. Cinara (Cinara) piniphila was recorded on Pinus mugo and C. (Cinara) nuda on Pinus heldreichii for the fi rst time. Partial COI and EF-1a sequences of C. (Cinara) hyperophila, C. (Cinara) pilosa and C. (Cinara) piceicola were obtained for the fi rst time. Partial sequences of mitochondrial (COI) and nuclear (EF-1a) DNA of Lithuanian samples were used to explore molecular diversity using NJ trees, Automatic Barcode Gap Discovery (ABGD), General Mixed Yule Coalescent (GMYC) and Poisson Tree Processes (PTP). Species delimitation using GMYC (both on COI and EF-1a sequences), PTP (BI on COI) and ABGD (EF-1a) were the most consistent with traditional classifi cations. Pairwise between-species sample divergences (COI and EF-1a fragments) of the samples of the species complex C. (Cinara) pinea - C. (Cinara) piniphila indicate it is composed of a single species. Of the species of aphids that live on conifers, there are seven species of the tribe Eulachnini that are likely to shortly colonize Lithuania. [ABSTRACT FROM AUTHOR]