Aquatic insects serve as vital inter-habitat linkages between aquatic and terrestrial ecosystems due to their life cycle encompassing both environments. They facilitate the flow of energy and nutrients and play a crucial role in transporting waterborne contaminants to terrestrial environments. Our project focused on investigating the environmental fate of emerging contaminants (ECs), particularly pharmaceuticals (PhACs) and endocrine disrupting compounds (EDCs), originating from wastewater effluents and accumulating in aquatic insects. Conducting in situ studies in NW Croatia, we demonstrated the bioaccumulation of multiple PhACs and EDCs in the aquatic stages of Odonata and Trichoptera. Subsequently, we observed their transfer across the aquatic-terrestrial ecosystem border via emerging adults. Comparison of EC concentrations in aquatic and terrestrial life stages indicated bioamplification, or increased body burden of many compounds, particularly in Trichoptera emerging adults. Furthermore, our results suggest that differences in biological traits between taxa, such as type of metamorphosis and feeding behaviour, play a defining role in bioaccumulation and bioamplification patterns of PhACs and EDCs in aquatic insects. Additionally, our results revealed the presence of waterborne PhACs and EDCs in terrestrial invertebrates in the riparian zone (e.g., Aranea, Isopoda, Coleoptera), shedding light on contaminant transfer in aquatic-terrestrial food webs across different trophic levels. Notably, trophic transfer of PhACs and EDCs was observed extending beyond a 3-meter distance from the river, underscoring the necessity for further research into the extent of waterborne contaminants in riparian zones. In summary, our findings contribute significant insights into contaminant transport mechanisms dependent on ecological processes linking aquatic and terrestrial ecosystems.

Man-made standing waters can provide important secondary habitats for freshwater invertebrates and other biota, but they also pose risks to the local biota through increased pollution levels. We studied the bioaccumulation of chemical elements, with emphasis on heavy metals, in common invertebrate and fish species in post-mining habitats in the Czech Republic. We developed a systematic approach to compare the bioaccumulation of 11 elements in a mollusc (Physella), four predatory insects (diving beetle Rhantus, heteropteran Nepa and larvae of Anax and Orthetrum dragonflies) and two fish species (Perca and Rutilus) in less polluted mining ponds and highly polluted fly ash lagoons.

The relationships between environmental and tissue concentrations were described by element-, taxon- and habitat-specific power law relationships. We showed that environmental concentrations determined the tissue concentration of non-essential elements (Al, As, Co, Cr, Ni, Pb and V) across all taxa. Bioaccumulation of all elements varied among taxa. We detected higher bioaccumulation of Al and Pb in mining ponds and of As, Cu, Mn, Pb, Se, V and Zn in fly ash lagoons, but the differences were often minor. Bioaccumulation of some elements further increased in mineral-rich localities. Tissue concentrations of most elements were more closely related to substrate than to water concentrations and the proximity to substrate, rather than trophic level, drove increased bioaccumulation levels across taxa. This highlights the importance of substrate as a pollutant reservoir in standing freshwaters and suggests that benthic taxa (Physella, Nepa) are good bioindicators of pollution levels. Despite the higher environmental risks in fly ash lagoons than in mining ponds, the observed ability of freshwater biota to sustain high pollution levels supports the role of post-industrial sites as refuge habitats in Central European landscape.

The western Balkan Peninsula is a karst upland and mountainous region where springs play a crucial role as habitats for benthic invertebrates. They harbour a significant portion of freshwater biodiversity, especially in areas lacking large rivers and lakes. Chironomidae and other midges are major components of spring benthos due to their short life cycles and dispersal abilities. Research conducted on the 37 rheocrenes of the Bjeshkët e Nemuna mountains in Kosovo and 19 springs in the Cvrcka River system in Bosnia suggests that species composition and biodiversity in the region are influenced by altitudinal hydroclimatic gradients and microregional landscape conditions. The midge communities reveal four altitudinal zones in the Bjeshkët e Nemuna mountains and three groups of springs in the Cvrcka River valley based on human impact. Springs utilised by humans on a moderate scale exhibit the highest midge biodiversity. This is because the efficient discharge and bottom substrate that favour midges coincide with suitability for human use. Higher mountain springs stand out from those in other altitudinal zones due to their perennial character, supported by the humid weather at 1400–1500 m a.s.l. The spring fauna displays a patchy distribution, and even rheocrenes located near each other may be inhabited by different species. These habitats should be recognised as supporting biodiversity resources, particularly in protected areas such as national parks, and should be sustainably utilised in rural regions.

Man-made alterations of natural habitats are a major issue in ecology and conservation of riverine ecosystems. This applies explicitly to construction of dam reservoirs which result in fragmentation of river habitat and transformation of lotic to lentic ecosystem. The latter has an impact on the biota of altered river reach by changing species composition and/or by altering life histories of species remaining in new habitat. In this study we tested if freshwater, alien spiny-cheeck crayfish Faxonius limosus shows variability in values of stable isotope ratios (δ13C and δ15N) related to the individuals’ origin (dam reservoir or river downstream). Presumably, stable isotopes should outline trophic aspects of crayfish life histories from different habitat types. We hypothesised that 1) overlap of isotopic niches (in δ13C vs. δ15N isospace) between two distinct habitats would be lower than between the same habitat types within locality; 2) niche width of crayfish from rivers is wider than from reservoirs; 3) trophic position (based on δ15N) of crayfish from rivers would be higher than from reservoirs; 4) crayfish with higher body condition index would show higher trophic position.

We analysed 379 crayfish from tree reservoir-river downstream pairs in South-Central Poland collected in 2019 due to body condition index analysis. Crayfish were weighted and measured to conduct further body condition analysis. Further, dried, and homogenised abdominal muscles were sampled for stable isotopes analysis. Samples included gradient of age (reflected in individuals’ sizes) from the youngest to oldest individuals available in the Autumn.

The following results were obtained (in order of hypothesis above): 1) overlap in isotopic niches were observed, but were not related to habitat type; 2) niche widths were not much variable with one exception of crayfish from the largest studied reservoir revealing the largest niche area; 3) trophic position, although variable, was not related to habitat type but more related to locality from where the crayfish were; 4) body condition index in general was not correlated with δ15N values, which suggest that resources allocation is not dependent on the type of food utilised.

The results show that in general there are differences in feeding strategies among crayfish from different localities, but they seem to be more related to very local food conditions than to habitat differences between dam reservoirs and rivers. Further studies, including more replications of river-reservoir pairs and/or variable riverine habitats are needed for better understanding potential impact of such ecosystem alteration on crayfish.

A ten-year-long examination of macroinvertebrate community recovery was conducted following a catastrophic spill of highly alkaline red sludge (pH>13) into lowland streams. Our primary objective was to compare recovery patterns after coarse and fine-grain disturbances, focusing on two aspects: i) trend analysis to reveal mean changes of six community parameters, and ii) variation analyses to assess parameter changes over time. We conducted statistical analysis on long-term data series of macroinvertebrates obtained from quantitative samples collected at four sections with varying degrees of disturbance along the impacted stream sections. We developed a comprehensive theoretical framework comprising a series of sequential phases: Ramp-up, Overshoot, and Oscillation Phases. i) A trend analysis revealed that disturbances show a gradual recovery pattern, while variance analyses showed an asymptotic convergence to an equilibrium. ii) Evaluating these trends across phases unveiled that the initial recovery phase exhibited a steep trajectory, lasting 4–9 months, irrespective of disturbance severity. Coarse-grain disturbances induced a remarkable Overshoot phenomenon across all community metrics. The more severe the disturbance, the greater the height and duration of the Overshoot. Our results suggest that the presence or absence of Overshoot can serve as an indicator for coarse-grain disturbances in the context of large and infrequent disturbances (LID). The entire recovery process lasts 2.5–3 years irrespective of the severity of the LID. In conclusion, a minimum survey duration of two and half years is deemed imperative to capture the phases of recovery, and changes associated with LID are not expected to extend beyond the three-year threshold. The theoretical framework, including Overshoot parameters, may assist future studies in comparing recovery patterns of different LID types. Furthermore, our theoretical framework is likely to be applicable to other groups of organisms given a sufficiently long monitoring of recovery, influenced also by the length of reproductive cycles.

Understanding the impacts of microplastic pollution on freshwater ecosystems is crucial due to its far-reaching environmental consequences. However, while the general understanding of microplastic pollution’s impacts is growing, there remains a critical gap in knowledge regarding the specific effects of different microplastic particle sizes. This study aims to address this gap by focusing on the distinct effects exerted by varying sizes of microplastic particles on the bioturbation activity of Chironomus riparius. Bioturbation, the process by which organisms disturb sediment layers through their activities, plays a significant role in sediment dynamics and nutrient cycling in aquatic environments. By investigating how microplastic particle size influences bioturbation patterns, this research seeks to provide insights into the mechanisms driving the fate and behaviour of microplastics in freshwater ecosystems. Methodologically, luminophore sediment profile imaging (LSPI) was utilised to follow the movement of microplastic particles within sediment layers. LSPI is a non-destructive technique that allows for the visualisation of particle distribution and transport dynamics in the sediment. Importantly, the study comprised two different size ranges of polyethylene particles: blue spheric particles (53–63 μm) and larger red spheric particles (250–300 μm), mimicking the luminophores. The particles were mixed in the first layer of sediment in equal proportions at a ratio of 0.076% (particles to sediment). Preliminary findings indicate that both large and small microplastic particles exhibit downward transport within sediment layers. However, there are notable differences in their interactions with C. riparius larvae and their impact on bioturbation patterns. Specifically, smaller microplastic particles appear to have a more pronounced effect on larval locomotive activity and are prevalent within the digestive tracts of the organisms. This suggests that particle size plays a crucial role in determining the bioavailability and uptake of microplastics by aquatic organisms, with smaller particles potentially posing a higher risk to ecosystem health. Furthermore, the temporal pattern of the reworking associated with the two different particle sizes shows distinct dynamics, highlighting the complexity of microplastic interactions in freshwater environments. Additionally, we observed that larger particles, intended to mimic the characteristics of luminophores, exhibit a different transport behaviour compared to it, suggesting the importance of particle shape in influencing their fate and behaviour in aquatic systems. Overall, this study contributes to our understanding of how microplastic particle size influences their fate and interactions within freshwater ecosystems, highlighting the need for targeted mitigation strategies to address the escalating threat of microplastic pollution.

Categorised as renewable or green energy sources, small hydropower plants (SHPs) are sometimes generalised as ecologically safe. However, in some cases, they are directly altering the natural hydromorphology of small rivers and indirectly the physical, chemical, and biotic parameters of these ecological systems at both local and water body-scale. Habitat deterioration may affect communities like fish, periphytic algae or benthic macroinvertebrates (BMIV) through mechanisms like increasing water transparency, flow and velocity, sediment types and granulometry changes and uniformization of microhabitats. BMIV, for example, are affected by rapid changes of water flow or depositional microhabitats for leaf packs.

European legislation does not require a unitary regulation of legal requirements, yet there are some recommendations to implement at a national level, based on the Water Framework Directive, like hydropeaking mitigation, minimum ecological flow, or sediment transport.

This study investigated, during spring and summer 2019, the ecological effects of 17 SHPs built on 22 headwater streams on macroinvertebrate communities in Romania. Sampling sites were located both upstream and downstream of the intake points of SHPs, aiming to quantify changes in the taxonomic composition of BMIV communities, assess the species-specific response of different BMIV species and identify the abiotic variables explaining the community structure and its spatial-temporal dynamics. Generally, a lower number of BMIV taxonomic families was recorded downstream of SHPs intakes. As expected, species explaining community structure belong to Ephemeroptera, Plecoptera and Trichoptera taxa. Among the stream bed hydromorphology and physical-chemical parameters, mean water depth, velocity, and flow are the most influential. Although, according to the Water Framework Directive, the ecological status based on BMIV community structure and diversity scored as “high quality” which does meet the European agreed goals, there are temporal variations of some indices which suggest potential future modifications and therefore a need for extended monitoring programs.

The river network of central Poland’s largest agglomeration – Łódź Agglomeration consists of dozens of small watercourses due to its location on a first-order watershed. In the 19th and 20th centuries, the river system was significantly transformed as a result of the city’s rapid growth, and many rivers were turned into sewers. For these reasons, many of the rivers within the city of Łódź are located in covered channels beneath the surface of the city. These canals create specific microhabitats and microclimates similar to those found in caves. To study these specific habitats, research was carried out in one of the underground river channels in the Łódź area. The chosen channel is 200-metre built from ferroconcrete prefabricate and is located under the former national road no. 1.

The main objective of the project was to assess the species diversity of the invertebrate fauna of the underground river channel and compare it to the fauna surrounding its inlet and outlet. To carry out the study, organisms inhabiting the channel were collected monthly for one year (04/2023–03/2024) from three microhabitats within the channel: dry walls, wet walls/groundwater seeps and river sediment. The collected material was determined to the lowest possible taxonomic level using morphological and molecular methods.

The results indicate a strong influence of the covered channel, and the thermal conditions present on the phenology and development cycles of insects. The groundwater outflows on the canal walls provide an important microhabitat for organisms requiring water of high purity. Only within this microhabitat larvae of Chaetocladius perennis (Diptera: Chironomidae) were detected. Also, the groundwater outflows were the only microhabitats where larvae of Eubria palustris (Coleoptera: Psephenidae) were observed. It was the first observation of that species in central Poland and one of the few known locations in such a highly urbanised area. Preliminary results show that the so far unstudied underground channels of rivers in Poland can be a habitat for rare and vulnerable species and exhibit greater biodiversity than was expected.

Most European countries use national assessment systems for freshwater bodies with the main objective of assessing the ecological status of water quality based on living organisms, including benthic macroinvertebrates as a biological quality element (BQE). As aquatic macroinvertebrate assemblages are typical of the different types of water bodies, they are used as important indicators of the prevailing aquatic ecosystem and directly describe the condition and quality of the water. In this study, we present data on the taxonomic composition, diversity, and community structure of bottom macroinvertebrates from Lake Prespa and the assessment of water quality based on the BQE benthic macroinvertebrates. The sampling was carried out in the period 2021–2022 at a total of seven sites across the shoreline of Lake Prespa in North Macedonia. Water quality of the littoral zone was assessed from moderate to bad (III–V class). Concerning the samples from the profundal zone, the collected specimens belonged to the Oligochaeta and Chironomidae groups, which indicates a higher degree of eutrophication of the lake’s ecosystem. The decline in water quality was primarily expected as a result of the lowering of the water level in the comparison of the two study years. Among the species endemic to Lake Prespa, Pyrgohydrobia prespaensis (Urbanski, 1939), Gammarus triacanthus prespensis (Karaman S. & G. 1959), Dreissena carinata (Dunker, 1853) and Atyaephyra thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012 were recorded. Nevertheless, within this survey we contribute to the specific lake’s macroinvertebrates community representatives and further to the unique endemic assemblages from Prespa Lake, that characterised the lake as a “unique hotspot”.

The study was made possible thanks to the Prespa Ohrid Fond Trust (PONT) grant “Lake Prespa Monument of Nature and Ezerani Nature Park: Operational Plans 2021-2023”.