Zelenci is a limnocrene spring in the South-Eastern Alps, attractive for its unique structure and known among researchers for its high diatom diversity. Our aim was to assess how abiotic factors influence the structure of diatom communities in different habitats and to compare the trophic status over 10 years of investigation. Four sampling sites were chosen: two for tychoplankton and two for epipelon. Achnanthidium minutissimum was the most abundant species in both habitats, while Navicula was the most diverse genus (17 species). Planktonic diatoms dominated plankton samples, while the motile ecological type dominated the epipelon. Of all diatom taxa, 23.5% had some endangerment status. Key factors influencing the Shannon-Wiener diversity index were water level, temperature, and concentration of NH4+. The most important abiotic factors for the tychoplankton community were temperature and NH4+, while the most important abiotic factors influencing the structure of epipelon communities were water level, NH4+, pH, and dissolved oxygen concentration. Trophic index revealed increasing inflow of nutrients to the spring; 10 years ago, they were oligotrophic to oligo-mesotrophic, whereas in the present, they are predominantly eu-mesotrophic to eutrophic, indicating human pressure from the catchment area.

This study investigates the sensitivity of subterranean amphipods of the genus Niphargus to nitrate pollution, focusing on understanding possible differences between cave-dwelling and spring-dwelling species. Five ecologically distinct subterranean crustacean species of the genus Niphargus were studied, three from springs at the interface between surface and subterranean ecosystems (Niphargus timavi, Niphargus spinulifemur, Niphargus sphagnicolus) and two from cave streams (Niphargus stygius, Niphargus podpecanus), together with Daphnia magna for comparative toxicity assessment. The organisms were exposed to nitrate for 72 h, 96 h and 21 days, followed by a 96-hour recovery period in a nitrate-free medium. In contrast to initial hypothesis, the results showed that nitrate did not induce immobility or mortality to any Niphargus species at concentrations higher than those environmentally relevant. The average 21 d LC50 values determined for different Niphargus sp. were 1735-4266 mg NO3-/L. No significant differences in nitrate sensitivity were found between cave-dwelling and spring-dwelling species. In addition, all species tested showed high recovery rates, regardless of their ecological origin. These results challenge the assumption that subterranean species are inherently more susceptible to chemical stressors due to their lower metabolic rate and lower detoxification capacities. This study highlights the importance of evaluating species-specific traits rather than relying solely on habitat-related generalizations. Although nitrate did not cause toxic effects in this context, potential long-term risks to groundwater ecosystems, such as effects on reproductive success and population dynamics, remain a concern. Comparing the sensitivity of Niphargus and D. magna after 72 h of exposure, N. timavi and N. stygius were more sensitive than D. magna, while N. sphagnicolus was similarly sensitive. These results suggest that tests on subterranean species should be performed to provide a more holistic understanding on the pollutant hazard for subterranean environment.

Different communities of primary producers were surveyed in a series of five river reservoirs on the Sava River in southeast Slovenia. Seasonal differences of phytoplanktonic and phytobenthic communities were studied in the reservoirs of hydroelectric power plants. Macrophytes were surveyed in the summer, while phytoplankton and periphyton were sampled in the winter and summer of 2021. The taxonomic composition of diatoms was studied in greater detail and additionally analysed. The results showed that the species composition of phytoplankton and phytobenthos differed between seasons. The communities were also more similar between the seasons at the same sampling site than between the sampling sites. Temperature was the parameter that had the greatest impact on the taxonomic composition of phytoplanktonic and phytobenthic communities. In total, 51 algal taxa and 81 species of diatoms were recorded, respectively. Furthermore, 15 species of aquatic macrophytes were found. The abundance of phytoplankton was the highest in the lowest reservoir in the series, in Brežice, where the temperature was also the highest. The number of macrophytes also increased downstream, but their abundances were low, mainly due to coarse substrate on the banks consisting of rocks and boulders. Constructing additional reservoirs on this section of the Sava River could increase the probability of the substantial growth of phytoplankton and cyanobacteria within it. On the other hand, providing patches of finer substrates (gravel, pebbles) would support the abundance of macrophyte species, which could control the concentrations of nutrients in the summer and prevent the blooms more efficiently.

Freshwaters are among the most threatened ecosystems globally, with biodiversity declining at far greater rates than the biodiversity of the most affected terrestrial ecosystems. There is an urgent need for accurate information on spatial patterns of freshwater biodiversity, a first step in effective conservation planning and management of these ecosystems. We explored patterns of aquatic macrophyte diversity in four waterbody types, rivers, streams, ponds and ditches, across three Central European regions. By analyzing local (α), among-site (β) and regional (γ) diversity, we assessed the roles of these ecosystems as biodiversity hotspots, particularly for red-listed species. Sampling 220 sites across Slovakia and Slovenia, we recorded 113 macrophyte taxa (31% of which were red-listed), with ponds and ditches consistently supporting higher α and γ diversity than running waters. β diversity was primarily driven by species turnover, with ponds displaying high heterogeneity linked to environmental variability. Our findings highlight the conservation value of artificial habitats like ditches and ponds, harbouring significant macrophyte diversity, including unique and threatened species. These results underscore the need to prioritize small waterbodies in biodiversity conservation strategies within agricultural landscapes.

This paper documents the different ways in which invasive alien species are introduced into new areas. The pathways by which invasive alien species spread, their history, and the characteristics of plants that enable them to spread successfully are described. The article discusses the competitive abilities of invasive alien species, their negative effects on other organisms, and the impact of global change on their spread.

The common reed (Phragmites australis) is a highly adaptable perennial grass that thrives in diverse wetland environments, capable of forming dense stands that are crucial for ecosystem services such as soil stabilization and habitat provision. At Lake Cerknica, long-term data on water levels and temperatures, combined with four decades of Landsat satellite imagery, allowed for a comprehensive analysis of reed stand dynamics of three different reed stands using the modified soil adjusted vegetation index (MSAVI2) and an index differentiating technique. Decision tree-based data mining using the M5P algorithm effectively identified significant changes in MSAVI2. Previous MSAVI2 values were key predictors for detecting increases in the following year, while water level data, particularly high summer water levels, were critical for identifying significant decreases. Smaller changes were less reliably predicted, but temperature data emerged as a more influential predictor in such cases. Long-term field measurements of common reed biomass confirmed the accuracy of remotely sensed data. Yearly dynamics of reed stands showed a consistent alternation between significant changes in MSAVI2 with short periods of smaller changes. The largest amplitude of change occurred at the reed stand most affected by disturbances. Despite these annual fluctuations, reed stands maintained long-term equilibrium but require continued monitoring to identify years where a decrease in reed vitality is expected. Consequently, mowing events in such years should be minimised. The findings highlight the utility of combining remote sensing with environmental data to develop predictive models that recognize changes of reed stand vitality, providing crucial information for effective reed management.

Ponds are important habitats for aquatic plants and other biota, particularly in regions where the quality of aquatic ecosystems is deteriorating or even disappearing. Ponds provide refuge for many species and serve as foraging places for others. The ponds studied are located in the Brdo Estate and are under special protection to maintain their educational and other ecosystem services. This study examined the temporal differences (20 years) of the plant communities in eleven ponds concerning eutrophication and/or other human pressures. Various measurements were taken between the two surveys to improve the quality of inflowing water. The selected ponds’ physical and chemical parameters, water depth, and transparency were measured. According to our results, water transparency and temperature significantly shaped the structure of the plant community and significantly influenced the presence and abundance of aquatic plants. The changes were reflected in the disappearance of four species of the genus Potamogeton, namely P. filiformis, P. lucens, P. pectinatus, and P. trichoides, which were recorded in 2001 but not in 2021. Secondly, the average number of plant species in the ponds has slightly increased in 20 years, mainly due to emergent plants. The construction of wastewater treatment plants in the catchment area prevented the eutrophication processes.

We investigated the impact of the effluent from four constructed wetlands on the structure of the macroinvertebrate and macrophyte communities in the receiving watercourses including the river Pesnica and the Sejanci Stream and Pavlovci Stream in NE Slovenia. Macroinvertebrates and macrophytes were sampled on the sites upstream and downstream of the inflows. Selected environmental parameters were also analyzed on each site. Among the measured chemical and physical parameters, the concentration of NH4–N in the water was the only one that was changed significantly by the inflow from constructed wetlands (CWs). The metrics obtained on the base of the macroinvertebrate community, including the values of diversity indices, the proportion of sensitive taxa and the saprobic index, revealed no significant statistical differences between the upstream and downstream values. Inflows of effluent also have no detectable impact on macrophytes. The removal of degradable organic matter, nitrogen, phosphorus, and suspended solids from the wastewater in studied CWs was sufficient to support this situation, and this has been encouraging to construct new CWs.

The diversity of macrophytes and macroinvertebrates in small standing waters of different origins and characteristics was investigated. This survey covered 19 ponds in the Drava field in northeastern Slovenia. The influence of the macrophytes on the macroinvertebrates was investigated and the main environmental factors that had the most significant influence on the composition of the two communities were identified. Sixty-seven taxa of macrophytes and seventy-three families of macroinvertebrates were identified. We found that a diverse macrophyte community has a positive effect on the macroinvertebrate community. In contrast, the dominance of a single macrophyte species has a strong negative influence on the richness of the macroinvertebrate community. The taxonomic richness and abundance of the macroinvertebrate community in the natural ponds was statistically significantly higher than that in artificial ponds. The significant differences in the environmental characteristics between the natural and artificial ponds, such as the macrophyte cover, conductivity, and riparian zone width, may account for these differences. Our study suggests that a greater diversity of macrophyte and macroinvertebrate communities in natural ponds is enabled by abundant but diverse macrophyte cover, low phosphorus content, and wide riparian zones, which require appropriate management of ponds and their catchments.

AbstractThe presence, abundance, and distribution of aquatic macrophytes and their growth forms in the river Krka in Slovenia were studied. The studied slow‐flowing lowland River Krka is also called a »green river« since it is overgrown with macrophytes from its source to its outflow to the river Sava. The environmental parameters of the river ecosystem were also assessed using the modified version of the RCE (Riparian, Channel, and Environmental Inventory) method. Within 24 sections reaching from 100 to 250 m, 23 taxa of macrophytes were found. Sections were distributed noncontinuously from the source to the outflow more or less equally along the river course. The invasive alien species Elodea canadensis reached the highest relative abundance, followed by Ranunculus trichophyllus, Potamogeton crispus, Myriophyllum spicatum, Ceratophyllum demersum, and Potamogeton nodosus. Potamogeton crispus was present in most of the studied sections followed by Nasturtium officinale and M. spicatum. The river offers suitable conditions for the high diversity of macrophytes regarding the type of substrate, low flow velocity, heterogeneity of habitats, and relatively high concentrations of nutrients. In comparison to the survey performed in 2003, when the river Krka was surveyed continuously from the source to the outflow, we found that seven of the submerged and natant macrophytes were not detected in 2020. Macrophytes, growing in the river Krka, indicated meso‐ to eutrophic conditions. Five species recorded in the river Krka are listed on the Red list of endangered species in Slovenia, indicating the need to conserve the river ecosystem.

This contribution discusses the use of field measurements and remotely sensed data in an exploration of the effects of environmental parameters on the riparian and littoral stands of the common reed (Phragmites australis) in an intermittent wetland in Slovenia. For this purpose, we created a normalized difference vegetation index (NDVI) time series extending from 2017 to 2021. Data were collected and fitted to a unimodal growth model, from which we determined three different stages relating to the reed's growth. The field data consisted of the above-ground biomass harvested at the end of the vegetation season. Maximal NDVI values at the peak of the growing season exhibited no useful relationship with the above-ground biomass at the end of the season. Intense and long-lasting floods, especially during the period of intense culm growth, hindered the production of common reeds, while dry periods and temperatures were helpful before reed growth began. Summer droughts exhibited little effect. Water level fluctuations exerted a greater effect on reeds at the littoral site due to more pronounced extremes. In contrast, more constant and moderate conditions at the riparian site benefited the growth and productivity of the common reed. These results can prove useful for decision making regarding common reed management at the intermittent lake Cerknica.

The structure of phytobenthic diatom communities was studied to reveal differences between natural and channelized river sections in Slovenia. As part of the national monitoring of surface waters, samples of phytobenthos were collected at 85 sites throughout the country according to standard protocols. At the same time, basic environmental parameters were also assessed. Trophic (TI) and saprobic (SI) indices were calculated based on diatoms and other algae, while diversity indices and gradient analyses were performed only for the diatom community. The results showed that channelized rivers harbor significantly more diverse benthic diatom communities than natural sections, mainly due to the significantly higher number of motile diatom taxa that are able to take advantage of more nutrient-rich and less-shaded river sections because of their high adaptability. Selected environmental parameters explained 34% of the variability in diatom community structure when taxa were classified into ecological types. The removal of Achnanthidium minutissimum yielded clearer results (24.1%) than the total species matrix (22.6%). Therefore, we suggest excluding this taxon from calculations of TI, SI, or other indices when it is determined as A. minutissimum complex, because A. minutissimum complex was most abundant in both types of reaches in our study and has a wide ecological amplitude, which reduces the indicative power of the diatom community in the evaluation of environmental conditions and ecological status.

Inland wetlands are one of the most vulnerable ecosystems on Earth and have one of the highest rates of decline in surface and biodiversity [...]

In alpine Lake Bohinj, which is an LTER site and a part of the national park, the occurrence and depth distribution of submerged and emerged aquatic macrophytes were analyzed. Nine submerged and one emergent macrophyte taxa were found in the lake: Myriophyllum spicatum, Chara virgata, Chara aspera, Potamogeton lucens, Potamogeton alpinus, Potamogeton crispus, Potamogeton perfoliatus, Potamogeton pusillus, Ranunculus circinatus with the synonym Batrachium foeniculaceum and the emergent species Phragmites australis. The depth of the vegetation zones was measured using a depth meter and their coordinates were recorded using a GNSS antenna with RTK receiver. These data were used along with a DEM of lake depths to accurately map the potential zone of macrophyte growth, which was based on the depths of macrophyte distribution. The potential zone of macrophyte growth consisted of 28 different transects and covered 240.14 ha of the lake. The macrophytes covered 5.55 ha. The most common and abundant species was M. spicatum. A significant difference in macrophyte cover was found between the south and north shores of the lake, with the south shore having more patches with a larger total area. A clear difference in macrophyte cover was also noted between the main inflow and outflow of the lake. The presence of macrophytes and their diversity varied in different parts of the lake due to differences in slope, depth and type of substrates.

Metals stored in sediments of lakes can bioaccumulate through the food chain, posing a risk to the environment and human health. Alpine lakes are supposed to be less affected by pollution than lowland lakes and are vulnerable to any changes and impacts in their catchment areas because of their remote position and ultra-oligotrophic character. Therefore, we used a model Alpine lake, Bohinj (in the Triglav National Park, Julian Alps, Slovenia), to evaluate the load of metals in the abiotic and biotic compartments of the ecosystem, in order to assess the spatial distribution of metals, and finally, to determine whether past and present human activities in the lake’s catchment area may be causing pollution. To this aim, the contents of Cu, Pb, Cr, Cd, Co, Mn, Fe, Zn, Hg and Ni in the sediment, water, and macrophyte samples were determined. The results showed that the average content of some toxic elements, especially in the sediments (Cd 0.52 mg/kg; Hg 0.03 mg/kg) and plants (Co 0.71 mg/kg; Cr 5.88 mg/kg) was elevated compared to natural background values. High Hg contents could be connected with natural geological sources, while other elements were probably of anthropogenic origin. High levels of all elements in the eastern part of the lake indicated long-term pollution, which could be a consequence of past iron extraction and military activities in the vicinity. On the other hand, high contents of elements in the water suggests that intensive touristic activities in the area may cause temporal pollution in the summer. The study sheds light on complicated processes governing the distribution of trace metals in Alpine lakes.

This study focuses on solving urban challenges, such as temperature reduction, urban stormwater management, noise reduction, air quality improvement, and CO2 concentration reduction, and suggests terrestrial and freshwater habitat types (HTs) found in Europe as innovative forms of nature-based solutions (NBSs). Establishing native HTs in various urban environments to solve urban challenges would enhance biodiversity at different levels and integrate this aspect into urban planning. This contribution builds on the recognition that vegetated surfaces are the most versatile NBS for addressing the broadest range of environmental problems in urban areas and on the understanding that the processes running within these green spaces offer the key to socio-ecological improvements of such areas. Employing a narrative literature review, qualitative content analysis, and interdisciplinary expert discussion, this paper defines why and how unaltered native HTs can be implemented as NBSs in the urban environment, indicates potential HTs for specific urban challenges, and presents an approach to the inclusion of HTs as NBSs in spatial planning documents at national, regional, and local levels. The proposed planning approach attributes added value to HTs and, by linking the concepts of NBSs and HTs, integrates them into urban planning.

The aim of this study was to reveal the changes of macrophyte community over time and along the course of the Ižica River. In 1996, 2000, and 2016, we surveyed the distribution and abundance of macrophyte species in the lowland Ižica River, which originates in the town of Ig and then flows through an agricultural landscape. We calculated the River Macrophyte Index (RMI), which reflects the ecological status of the river. In 2016, ecomorphological conditions of the river, using the Riparian, Channel and Environmental inventory, were also assessed. In just 10.5 km of the river, we identified 27 taxa of macrophytes, among which Potamogeton natans, Sagittaria sagittifolia, and P. perfoliatus were the most abundant. Detrended correspondence analysis showed that, in 1996, the surveyed stretches differed more according to macrophyte composition than in the following years. The assessed environmental parameters explained 43% of the variability of the macrophyte species; riverbank stability explained 20%, riverbed structure 10%, while vegetation type of the riparian zone and bottom type explained 7 and 5%, respectively. The species composition of the macrophyte community revealed significant changes over the years of the riverine ecosystem. Comparison of RMIs in 1996 revealed better conditions in the upper and middle part of the river, while in 2016, the situation was the opposite, since the conditions in the upper part deteriorated significantly over time, while the lower part of the river had the best ecological status. These changes may be due to a considerable increase in the population of the settlement Ig, while better status in the lower course of the river may be a consequence of improvements in the infrastructure and the use of sustainable agricultural practices in the catchment due to the establishment of a formal area of protection.