Field of Study – Ecology and Environmental sciences (N 012)

Chemical pollution is one of the global anthropogenic factors accelerating the decline of biodiversity. Current methods for environmental monitoring and assessment primarily focus on chemical and ecological measurements, with limited exploration of their interaction, specifically the biological impact. The assessment of chemical status does not ensure compliance with the description provided in Descriptor 8 of the Marine Strategy Framework Directive (MSFD), which outlines the essential requirements for achieving good environmental status of marine ecosystems. Existing EU regulations, such as the MSFD and the Habitats Directive, are already undergoing review, emphasizing the need for integrated chemical and biological monitoring and assessment systems. In order to uncover the potential of integrating chemical-biological monitoring, this dissertation research will investigate the impact of chemical pollution on aquatic ecosystems, particularly on species health. Studies will be conducted using Atlantic salmon and sea trout as model species to evaluate their suitability for chemical-biological monitoring, assuming that these migratory fish exhibit a high potential to reflect cumulative and synergistic environmental pollution effects. The investigation of fish will encompass cytogenetic, biochemical, hematological, population parameter, and biological biomarker analyses to assess their health during the spawning migration period. To identify individuals and monitor changes in the studied biomarkers over time, captured individuals will be tagged with internal radio-frequency identification (RFID) markers. The study aims to detect early genetic biomarker signals of environmental pollution effects, conduct comparative analyses of these biomarker responses in fish from various rivers in Lithuania, and establish baseline levels of cytogenetic biomarkers in salmonid fish species. These investigations have the potential to promote the integration of biological effect assessment into the monitoring programs of aquatic ecosystems, thereby enhancing our comprehension of the cause-and-effect relationships between environmental pollution, biodiversity alterations, and ecological conditions. The research findings can serve as a foundation for the implementation of novel criteria, the formulation of practical recommendations for biological effects assessment, and the advancement of methodologies for evaluating the status of aquatic ecosystems.

The fate and behavior of nano-sized materials in aquatic ecosystems, as well as their interactions with other organic and inorganic pollutants, remain largely unexplored, presenting a real challenge. Data regarding the combined effects of nanoparticles (NPs) and various pollutants on aquatic organisms, food chains, and ecosystem sustainability are notably scarce. NPs exhibit unique physicochemical properties that render them useful in fields such as biomedicine, industry, and environmental protection. Within the European Union, efforts to tighten controls on hazardous pollutants and increased environmental requirements for preserving a sustainable environment and human health continuously stimulate the search for innovative wastewater treatment technologies. Certain NPs have robust sorption capacities, making them viable candidates for removing pollutants from aquatic environments. However, once introduced to the environment, NPs may accumulate in aquatic ecosystem, potentially leading to unpredictable changes in the functional status of organisms. A full comprehension of the impact mechanisms of NPs interactions with other pollutants requires additional research to elucidate how the physicochemical properties of NPs are related to their effects on living organisms. In this investigation, we aim to explore the effects of carbon-, metal-, and polymer-based NPs, as well as their mixtures with metals and pharmaceuticals, on fish and crustaceans. Our methodology will not only employ conventional ecotoxicological techniques but also take advantage of an innovative system breeding and rearing (Tecniplast), evaluating morphophysiological parameters (Danioscope and Daniovision), and utilizing analysis systems (Embryonet, MetaboAnalyst) for Danios rerio and other small aquatic organism. This study aims to examine, for the first time, the complex influence of NPs and various pollutants on aquatic organisms during their early, stress-sensitive developmental stages (i.e., embryos, larvae, fry). We will determine the interactions of NPs with various pollutants and evaluate their effects based on NP size, shell type, and structure. The acquired results will be instrumental in elucidating the mechanisms of metal- and carbon-based NPs’ effects on aquatic organisms. It will also broaden the application possibilities of NPs in environmental protection and biomedicine.

From a scientific and environmental point of view, understanding how environmental factors and impacts, including anthropogenic ones, can affect the hydrology of rivers, their water quality and related to river basin ecosystems is essential. At the moment, there is an increased interest of possible emissions from the Belarusian nuclear power plant (NPP) and the response of the environment to them. Whereas the probability of sudden incidents of a large impact on the environment at nuclear power plants are minor, but when they occur lead to different level consequences due to sudden and strong destructive properties. One of the purpose of this work would be to create a predictive model of the Neris River assessing the impact of possible events leading to environment pollution. With the consequences of such events, we must learn to live, at least reasonably from a scientific point of view. Also, based on isotopic studies of the water system, to develop a dynamic model for tracking pollution sources, which could characterize the relationship between the water system and the source of risk, is of primary importance.
River systems are very complex, so modeling is one of the important tools that can show the impact of different events under different conditions. The developed risk assessment model would be an effective tool for systematically quantify random uncertainty due to processes in the river system, as well as providing information when making decisions on the control of sudden water pollution, identifying critical sources and quantities of pollution. For the implementation of the work, isotopic research methods and a modern modeling program would be used.
The importance of the transfer of tritium in aquatic ecosystems was highlighted in studies performed in Canada and France (CNSC 2010; ASN 2010). Calibration of the transport model according to tritium data in rivers and modeling of the groundwater age was carried out in the western basin of Lake Taupo, New Zealand (Gusyev et al. 2013). To better understanding the transport process simulation of HTO from surface water to the atmosphere was carried out (Marang et al. 2011). Modeling of groundwater discharges into the river based on radon mass balance using tritium data was performed on the Elbe River, Germany (Schubert et. al 2020). The characterization of water systems is therefore an important for both issues such as construction of new nuclear power plants and the decommissioning of old ones. Transport models realize a mathematical description of the movement of radionuclides in a particular component of the environment (air, surface water, groundwater, biota) the purpose of which is to predict the concentration of radionuclides. In Lithuania, investigations of water systems using modelling tools were carried out mostly in relation to groundwater. Number of studies have focused on the formation of groundwater in the Baltic Artesian Basin (Vaikmäe et al., 2001; Cheban, 1966; Mokrik and Vaikmäe, 1988, Mokrtik et al. 2014; Mokrik and Samalavičius, 2021). The research interests include various aspects of palaeohydrogeology, origin issues and formation scenarios. Isotopic studies of the hydrological cycle including precipitation, streams and lakes, groundwater and other water bodies were performed since the beginning of operation of the Ignalina Nuclear Power (Jakimavičiūtė-Maselienė et al. 2012; Vaitkevičienė et al. 2013; Mazeika et al. 2013; Jefanova et al. 2018).
Because of the tritium mobility in hydrological cycle and well-known atmospheric abundance it is of great importance in line with other mobile radionuclides to carry out tritium measurements in the water bodies surrounding nuclear facilities and use data fot the environmental quality and risk assessment.

Due to their functional and magnetic characteristics, graphene and iron-based nanocomposites have attracted remarkable scientific and economic interest in biotechnology and nanomedicine. In recent years, there has been a significant focus on the practical application of functionalized magnetic adsorbents in water purification processes, particularly when combined with magnetic separation technologies. Considering that the production and use of nanomaterials will only increase in the future and that legal regulation of these materials in the manufacturing and waste management sectors has yet to be implemented, research on the impact of these nanoparticles on aquatic organisms in the context of a changing environment becomes important.

Magnetic nanoparticles possess a magnetic moment, enabling them to generate a magnetic field or respond to one. The primary sources of (electro)magnetic fields are wind turbines and their accompanying infrastructure. The development of renewable energy resources is gaining momentum worldwide, including in Lithuania. A 700 MW wind turbine power station is expected to be operational in Lithuanian territorial waters in the Baltic Sea by 2028. However, there is currently a lack of scientific evidence regarding the effects of (electro)magnetic fields on species in marine ecosystems.

The examination of these materials’ shape and functional properties will include parts of the synthesis, modification, and characterization of specific graphene and iron nanoparticles, as well as their nanocomposites. The hazardous effects of these nanomaterials on fish and invertebrates will be examined at several levels of biological organization to find patterns of nanoparticle impacts on organismal functional systems, biochemical and behavioral response patterns, and probable toxicity pathways. Comparative studies will be conducted on the anthropogenic effect of (electro)magnetic fields on aquatic organisms, employing sophisticated indicators of biological response and biomarkers. The regularities of nanoparticle toxicity will be investigated in the relationship between (electro)magnetic fields and chemical stress to better represent the effect of the multifunctional environment on the biological accessibility and toxicity of nanoparticles. The findings may be used to forecast potentially harmful quantities of these nanomaterials in the environment, as well as their interactions with physical stressors, which might generate complicated biological impacts in the context of a changing environment.

Laboulbenialean fungi (Laboulbeniales, Ascomycota, Fungi) are microscopic superficial parasites of arthropods. The Laboulbeniales are a group of insect-associated fungi with a relatively strong specialisation, with 145 genera and about 3000 species described (Thaxter, 1926; 1931, Tavares, 1985, et al.), but current estimates suggest that there are at least 40,000 species awaiting description (Haelewaters et al., 2020; Kirk, 2019; Weir & Hammond, 1997). The effects of Laboulbeniales fungi on their insect hosts are not fully understood and there is still very little research on their ecology and biology (Haelewaters et al., 2021). Only a small number of countries have ongoing research on Laboulbeniales, but the diversity and uniqueness of this group of fungi undoubtedly makes it a source of new taxonomic and ecological information. The taxonomic characters of Laboulbeniales are based on the structure of the fruiting body, i.e. the visible part of the fungus outside the host. The attachment of the fungus through haustoria and its spread within the host remains largely unknown, but it has been established that some Laboulbeniales species have a haustorial structure that penetrates the cuticle of the host, while others  only attach  to the cuticle of the host, but do not penetrate it, and it is not clear what nutrients they use for their own growth ( Reboleira et al., 2021). The first major comprehensive taxonomical work on Laboulbeniales, which resulted in a 6-volume monograph, was carried out in the Americas by Roland Thaxter (Thaxter, 1926-1932). Among European countries, more detailed studies on Laboulbeniales have been carried out in Italy (Rossi, 1978; 1979), Spain (Santamaria, 2020; 2001) and Poland (Majewski, 1994; 2008). The first studies in neighbouring Latvia (Briedis, 1932) and in Lithuania were carried out almost 100 years ago (Siemaszko and Siemaszko, 1928; 1932). During the last decade, the Belgian entomologist De Kesel (2006) found, described and published several new species in Latvia. This ecologically interesting group of fungi has hardly been studied in Lithuania, and there is very little data on the diversity, distribution and ecology of Laboulbenialean fungi – only two papers have been published (Markovskaja, 2000; 2006). Biodiversity research will undoubtedly have to include taxonomic studies, as there is a high probability of discovering new species. Scientists currently studying Laboulbeniales in Belgium, Spain and Italy are more involved in diversity, ecology and taxonomy research and are in close contact with each other, organising joint expeditions and hosting interns. This international collaboration has resulted in several papers on Laboulbeniales from Bulgaria, Hungary, Czech Republic, Slovakia and other countries (Pfliegler et al., 2016; Rossi et al., 2019; Rossi & Santamaria, 2020).

The research to be carried out in the dissertation

Field surveys: collection of material (arthropod insects) in different regions and habitats of Lithuania. Laboratory studies: selection of infected insects using a stereomicroscope, removal of fungi from the insect and production of permanent preparations, identification of insects and fungi using light microscopy.

Inspection of existing entomological collections at the VU, GTC, and Tadas Ivanauskas Zoological Museum in Kaunas, as well as of amber collections with insect inclusions, to look for infected insect specimens with Laboulbeniales fungi. Close cooperation and consultations with entomologists in Lithuania and abroad. Internship abroad with one of the best Laboulbenialean fungi specialists ( W. Rossi / S. Santamaria or other).

Most fungi in this group are highly specialised and through a long coevolutionary process adapt to parasitise a particular insect species or genus. Correct identification of Laboulbeniales depends primarily on correct host identification. The identification of insects will require entomological knowledge, which will need to be developed.

Taxonomic and ecological analysis of the collected material, determination of the distribution and host specificity of the insects, clarification of the trophic relationship between host and parasite. Use of molecular methods for the identification of new species and morphologically similar species, phylogenetic analysis. Preparation and publication of taxonomic and ecological papers. Preparation of an illustrated synopsis with species descriptions.

Soil is one of the most valuable natural resources, consisting of mineral particles, organic substances, water, air and living organisms. Every year, more and more functions of soil are being elucidated, and soil plays an active role in maintaining the quality of groundwater, surface water, and the atmosphere. Especially many microscopic fungi are found in forest soil. Forest soil is a major reservoir of microorganisms with a significant influence on organic carbon accumulation, soil structure, fertility, productivity, and plant growth. The main function of microscopic fungi in the soil is the active decomposition of organic matter. Fungi are able to synthesize and release into the environment a lot of hydrolytic enzymes that break down any organic matter, besides releasing organic acids, they dissolve phosphates that are difficult for plants to access, thus improving plant nutrition. The microscopic fungi of the upper mineral soil layer of the forests of Eastern and Southeastern Lithuania, their diversity, biological properties, and destructive properties will be studied. Microscopic fungi from the soil will be isolated by classical microbiological methods, and identified by phenotypic and molecular methods, their abundance and distribution will be determined, and their various enzymatic properties will be studied. The aim will be to obtain new knowledge about the intraspecific and interspecific diversity of microscopic fungi in the upper layer of the soils of Eastern and Southeastern Lithuania. New and valuable species/strains of microscopic fungi will be added to the Microorganisms Collection of the Laboratory of Biodeterioration Research.

The Ponto-Caspian region (the lower basins of the Black, Azov, and Caspian seas) is an evolutionary hotspot that harbors an unusual aquatic fauna particularly adapted to significant salinity fluctuations. Many of these adaptable species of crustaceans, fishes, mollusks, and annelids have invaded inland waters of the Northern Hemisphere over the past century, causing local extinctions of native species and restructuring of ecological communities. Of the invasive Ponto-Caspian species, amphipod crustaceans are the most numerous. Despite their noted negative impacts and the ever-increasing threat due to global warming, the factors that promote invasion success are incompletely understood, with increased fecundity and aggressivity thought to be important. It is also not known whether the aliens occupy the same ecological niche as the native species – if not, the replacement of native species with invasive ones might have a significant effect that would ripple throughout the ecosystem. The main aim of the proposed topic is to compare native and invasive Ponto-Caspian amphipods from Lithuanian inland waters in a multidisciplinary framework that would combine field research and laboratory experiments with functional morphology. Specifically, it seeks to understand (1) how amphipod morphology (e. g. body shape, size, and appendage length) is related to habitat preference, (2) how it influences the outcome of interspecific agonistic interactions and (3) predation by fish, and use it to test (4) if invasive species can trigger relatively rapid adaptation of native species. The results would significantly improve our understanding of the ecological niches of both the native and alien species and could also help predict the effects of the invaders that are expected to arrive in the future.

The Lithuanian territory is characterised by two types of forest biomes – broadleaved and mixed forests and boreal forests, the boundary of which is relatively defined by the edge of the Carpinus betulus distribution. Lithuania’s geographical position thus means that the vegetation of the region is characterised by transitional features, with combinations of different species that are not always clearly ecologically or phytogeographically related. In addition, the diversity of forest communities is particularly shaped by human activities. Traditionally, vegetation data have been collected in so-called representative communities, bypassing damaged and disturbed communities. Therefore, the aggregation of data collected in this way does not always reflect the actual state of the vegetation. This study would aim to reassess the state of forest vegetation and how it has changed over the last few decades: to identify which changes in communities may have been caused by  (1) geographical factors, (2) human activity related to forest use, and which have been caused by (3) a changing climate. Data would be collected on transects reflecting use, biogeographical and climatic gradients. Vegetation-plot sites would be selected based on historical data stored in the Lithuania vegetation database (EU-LT-001). Such knowledge would make a significant contribution to a re-survey of European vegetation, aiming to distinguish between long-term and random patterns of vegetation dynamics, to scientifically justify the practical aspects of the nature restoration strategy.

The thesis is based on the study of new alien and spreading over EU insect pests, polyphagous Otiorhynchus sp. (Coleoptera, Curculionidae) weevils. These weevils damage many species of shrubs and trees, ornamental and horticultural plants, and can cause significant harm to red raspberries and strawberries. The pests damage both the underground and the above-ground parts of the plant: larvae feed on roots meanwhile adults on leaves. Since the use of conventional pesticides and the increase in their use is harmful both to the environment and to humans, monitoring and environmentally friendly control measures, which are still not developed today, are necessary. To develop them, chemo-ecological and genetic studies on the insect pests will be carried out. Olfactory and behavioural reactions of the insects to volatiles of host plants will be registered as well as those of conspecifics and electrophysiologically active compounds will be identified for the Otiorhynchus sp. species studied. Attractive compounds of plant origin (kairomones) and those of insects (pheromones) will be tested in the field and the most effective blend will be recommended to use in traps for monitoring or control purposes. The genetic diversity of these pests will be investigated to assess the pathways of spread of alien Otiorhynchus sp. species to Lithuania.

Natural vegetation in forests, meadows and wetlands provides habitat for a wide range of species, meets their ecological needs and can keep species populations stable. Therefore, it is essential for the conservation of biodiversity in the hemiboreal region. However, increasing global human populations and climate change have led to an increase in the area used for agriculture, which has led to the destruction of some communities and fragmentation of others. Estimates suggest that globally as much as 90% of deforestation is being converted to farmland. In Lithuania, arable land accounts for about 46% of the total area, and in some areas, agricultural land accounts for more than 75%. Only pioneer forest patches introduced by man or abandoned on sites, wet scrub in the first successional stages at the base of slopes or strips of dry scrub on slopes remain in the agricultural landscape.

Can these disturbed communities contribute to biodiversity stability in a landscape degraded by agricultural activity? An analysis of the vegetation plots collected by traditional vegetation surveys cannot answer this question unequivocally. Therefore, field research and data collection will be carried out during the preparation of the thesis. The data will be collected in study areas (approximately 100 km²) distributed across the country, reflecting natural environmental conditions and differences in land-use practices. Vegetation plots will be carried out in forest and shrub communities, with additional data collection reflecting the geographical, climatic and ecological features of the communities.

The results of the research would contribute significantly to a more complete assessment of the European vegetation survey, while at the same time assessing the effectiveness of ecoschemes under good agri-environmental condition standards in protecting biodiversity.

During the last decades, anthropogenic pressure on freshwater ecosystems has significantly increased. To a large degree, such impacts are related to contamination by toxic elements and nutrients. In the long term, pollution results in a decrease in biodiversity and leads to the loss of balance in complex environments, disrupts or even destroys natural self-regulatory mechanisms, and often causes irreversible changes at different levels of biological organization. Small urban lakes are subject to exceptionally high, long-term anthropogenic impacts. At the same time, these water bodies are intensively used for social purposes and provide a wide range of essential ecosystem services. There is a considerable lack of research on small urban lakes, as most national monitoring surveys are carried out on lakes larger than 50 ha, according to the Water Framework Directive (2000/60/EC) recommendations. The thesis will aim to assess the ecological status of small urban lakes; by determining the concentrations of hazardous pollutants in sediments and biota, bloom-causing algae and their toxins, and by investigating geno-, cytotoxicity, and biochemical parameters in bioindicator organisms. Background levels of studied parameters will be determined in lakes, which are located at some distance from sources of contamination and, based on the results of the chemical analysis, are considered as not polluted. The impact of toxins released during water blooms will be assessed under laboratory conditions. Active monitoring experiments will be performed in situ by translocating bioindicator organisms to the lakes affected by long-term severe contamination, aiming to assess the level of adaptation of local, aboriginal organisms and to determine the true values of studied biomarkers. The research in this thesis should initiate significant changes in the monitoring, protection, and management of small urban lakes.

Microplastic (MP) pollution is a growing concern and is now one of the most important scientific issues in the field of ecology and environment. Previous studies have shown that the ingestion of MPs is widespread among many aquatic species, including fish, crustaceans, and marine mammals. In aquatic organisms, MPs can cause a wide range of toxic effects, including growth inhibition,
histopathological changes, oxidative stress, metabolic disturbances, behavioral changes, inflammatory reactions, and others. The toxicity of MPs is exacerbated by their ability to adsorb and transport chemical pollutants and pathogens, posing additional risks to aquatic organisms and humans in the food chain. The toxic effects of MPs in marine ecosystems are currently beingextensively investigated. However, less attention has been paid to freshwater organisms, and as a consequence, the ecotoxicological effects of MPs in these ecosystems have not been sufficiently investigated. Given that freshwater ecosystems are direct reservoirs and transporters of MPs, and are also characterized by lower water volumes and a greater dependence on anthropogenic activities, freshwater biota are at a higher risk of exposure to MPs. The thesis will include experimental studies on the toxicity of various polymer types of MPs, nanoplastics, and tire wear particles to salmonids, which are one of the main sources of MP pollution in the environment. Cytogenetic, biochemical, hematological, and biological parameters will be assessed to evaluate the toxic potential of MPs for salmonids at different stages of their development and to predict the mechanisms of toxicity. The results will be useful for the development or adjustment of current guidelines for the assessment of exposure to complex stressors and environmental risk, and may contribute to the improvement of monitoring programs for aquatic ecosystems. The research may also contribute to the integration of biological-chemical monitoring, leading to a better understanding of the cause-effect relationships between environmental pollution (as a causal factor) and changes in biodiversity and ecological status in aquatic ecosystems. Additionally, the research could provide a basis for the application of new criteria, the development of practical guidelines for the assessment of biological impacts of MPs, and could contribute to methodological advances in evaluating the status of aquatic ecosystems.

The aim of the study is to investigate changes of host – parasite interactions in wild mammal populations in the gradient of increasing anthropogenic pressure.
The object of the study is mammals and their parasites. During this research, parasite diversity of various mammalian species will be investigated with special attention to zoonotic diseases. Factors shaping parasite communities in changing environment will be analysed. Obtained results will provide valuable information how changing environment affect host and parasite communities.

Amphipod crustaceans play a key role in macroinvertebrate communities and the diets of bentophagous fish in lakes. As part of global change, in many places, native amphipods are being displaced by the invasive ones from the Ponto-Caspian region (the lower basins of the Black and Caspian seas). In Lithuanian lakes, intentionally introduced alien amphipods have spread the most, but soon they will also have to face competition from the aggressive self-dispersed compatriot species. Temperature and dissolved oxygen should be investigated as the primary factors that determine the species’ competitiveness and the likely changes in the amphipod assemblages as the climate warms and lake productivity increases. In turn, amphipod species differ in their preferences to feed on plant detritus, filamentous algae, fine organics, or small animals. Shifts in their assemblages can thus lead to significant changes in lake functioning. This work aims to investigate the competitiveness, dietary preferences, and potential effects on lake functions of native and invasive amphipods that occur or are spreading across the lakes of our region under warming climate conditions. The topic foresees laboratory and field studies on the influence of temperature on oxygen consumption (1) and coexistence (2) of amphipod species, their feeding preferences (3), and the influence of amphipod assemblages on the functional structure of macroinvertebrate communities and the overall function of detritus shredding (4). The results will significantly contribute to the ecological knowledge of invasive species spreading across Europe and will help to predict shifts in amphipod assemblages as well as the associated ecosystem changes.