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Odonates are one of the best-known aquatic insect groups, with the renowned ability to reflect the quality of freshwater ecosystems. In the last few decades, major emphasis has been placed on the importance of secondary aquatic habitats as refugia for odonates. Biota of man-made habitats, especially dams, are burdened by countless negative anthropogenic impacts. Nevertheless, some habitat types appear to be able to support species with high conservation value. Here, we used generalised linear models to analyse the effects of several environmental characteristics, such as pH, conductivity, water area and perimeter of selected sites, to clarify the effects of drivers in terms of species richness of odonates. Water dams, flooded quarries, flooded gravel quarries and flooded sandpits have been compared based on the Dragonfly Biotic Index (DBI). We recorded 44 odonate species, including several red-listed ones, such as Epitheca bimaculata (Charpentier, 1825), Leucorrhinia caudalis (Charpentier, 1840) and L. pectoralis (Charpentier, 1825). Although the highest numbers of species were found at water dams, at such habitats, the lowest values of DBI were revealed. The fractional effect of habitat types on DBI was also proven to be significant. Increased conductivity resulted in a decrease of species richness. The positive correlation between habitat area and DBI was also proven to be significant. Our results indicate a high conservation value of different types of flooded quarries counter to water dams, based on the presence of several nationally threatened species with high values of DBI. [ABSTRACT FROM AUTHOR]

Lakes located in the Polish and Slovak parts of the Tatra Mountains were included in the Tatra diatom database (POL_SLOV training set). The relationship between the diatoms and the water chemistry in the surface sediments of 33 lakes was the basis for the statistical and numerical techniques for quantitative pH reconstruction. The reconstruction of the past water pH was performed using the alpine (AL:PE) and POL_SLOV training sets to compare the reliability of the databases for the Tatra lakes. The results showed that the POL_SLOV training set had better statistical parameters (R2 higher by 0.16, RMSE and max. bias lower by 0.2 and 0.36, respectively) compared to the AL:PE training set. The better performance of the POL_SLOV training set is particularly visible in the case of Przedni Staw Polski where the curve of the inferred water pH shows an opposite trend for the period from the 1960s to 1990 compared to that based on the AL:PE dataset. The reliability of the inferred pH was confirmed by the comparison with current instrumental measurements. [ABSTRACT FROM AUTHOR]

Paleolimnological research in the territory of Slovakia has relatively short history with the beginning in the 1990s primarily as a response to the ecological changes in mountain lakes due to air pollution and missing data from the pre-industrial period as well as a need to quantify anthropic impact on the landscape. In the present paper, we reviewed 53 publications, including research papers, monographs, conference abstracts and theses, dealing with aquatic proxies in Holocene lake sediments to identify (1) the location of surveyed sites, (2) proxies used, and (3) the object of the paleolimnological reconstructions. The vast majority (37) of the analysed paleolimnological localities (51) took place in the High Tatra Mountains, focusing on the alpine lakes of glacial origin. The most frequently used biological proxy was Chironomidae remains (44%). In contrast, Cladocera, Ostracoda, loss-on-ignition, molluscs and stable isotopes were used only in 10-12% of studies. Most studies (84%) focused on a simple ecological reconstruction of the past environment, and only 24% of the studies attempted to reconstruct specific ecological variables, properties and processes, such as acidification (10%), temperature (8%) and eutrophication (4%). Only 2% of the studies used molecular techniques. Sixteen out of the 51 cores analysed (i.e., 31%) were dated by radiometric methods. In the end of our review we pinpoint the weaknesses of the local paleolimnological research and sketch possible future directions. [ABSTRACT FROM AUTHOR]

The climatically most extreme lakes in the High Tatra Mountains are populated with species-poor chironomid communities dominated by Micropsectra radialis and Pseudodiamesa nivosa. Based on paleolimnological studies from other parts of Europe this community had been hypothesized to be a relict of the Late Glacial period, however, this assumption has not been proved in the Tatras. A paleolimnological survey of a subalpine Tatra lake demonstrated that this community was indeed occupying lakes located even in relatively low altitudes as long as they were glacially influenced, i.e., until the early Holocene. Due to the restricted distribution and specific ecological requirements of the species creating this relict community, it is extremely prone to extinction. [ABSTRACT FROM AUTHOR]

The decline of species richness with altitude is one of the most obvious patterns in ecology and results from the combination of ecological and evolutionary mechanisms. In harsh high-altitude environments, the effect of altitude usually overrules other environmental variables related to biodiversity. Studies using species richness along altitude gradients in high altitude are relatively numerous for lakes, but not for ponds. However, due to their special features, such as small size, high isolation and regional variability, ponds have been proved to be different systems compared to lakes. In high-altitude waterbodies, species of the family Chironomidae often dominate in benthic invertebrate communities and thus serve as an ideal model to study aquatic community changes along an altitude gradient. However, due to the time-consuming processing and expertise needed to identify the species, chironomids are often excluded from regular surveys. In the present study, we sampled 66 Tatra ponds over a 1100-m altitude gradient for benthic invertebrates, with special attention to chironomids. Out of the total 122 taxa collected, Chironomidae constituted the richest group with 58 taxa, being present in all the study ponds. The most diverse pond supported 13 chironomid taxa, and mean diversity was 6 taxa/pond. While total invertebrate richness decreased with altitude, chironomid richness showed only a weak negative response to altitude. The proportion of total chironomid diversity made up of Tanypodinae and Chironominae subfamilies decreased with altitude, while the opposite trend was recorded for the proportion of Diamesinae and Orthocladiinae. [ABSTRACT FROM AUTHOR]

The dispersal of aquatic insects plays an important role in the colonization and recolonization of newly created and previously disturbed habitats. The heavy acidification of some alpine lakes in the Tatra Mountains, Slovakia, was followed by rapid chemical recovery starting in the 1990s; however, the recolonization of aquatic insects has been delayed, potentially due to the limited dispersal of aquatic insects in the alpine environment. Therefore, to investigate dispersal ability of aquatic species in situ, we set up 120 yellow pan traps on 12 transects evenly distributed over a distance of about 600 m between a non-acidified and a formerly acidified alpine lake. A total of 1,202 aquatic insect adults were caught. Chironomidae dominated but adults of Trichoptera, Plecoptera and Ephemeroptera were also recorded. For both lakes the total number of adults declined exponentially with distance from the lakes, and negative binomial models predicted that virtually no imagoes would be found beyond 300 m from the lakes. The majority of species were recorded within 150 m of the lake shore with the exception of two chironomid species. Such a low dispersal potential of aquatic insects between alpine lakes could explain the slow biological recovery of some lakes following disturbance by acidification stress. [ABSTRACT FROM AUTHOR]

Attempting to help reduce the costs of bioassessment of aquatic habitats, the aim of this study was to estimate how particular substrate types influence the ecological quality evaluation based on a multihabitat scheme proposed by the AQEM/STAR consortium. Samples of macroinvertebrates were taken from the Stupavský potok brook, a small, 4th order calcareous stream in the Small Carpathians in Slovakia (Central Europe). Eight most suitable metrics for small Slovakian streams forming the Slovak multimetric index on seven substrate types were tested and compared with the multihabitat sample. The Saprobic Index (SI) and Index of Biocenotic Region (IBR) showed considerably worse (higher) values in the psammal and the best (lowest) values on coarse mineral substrates (lithal, akal). Similarly, values of the metrics Oligo (%), BMWP Score, Rheoindex, Rhithron Typie Index (%) and EPT reached their worst (lowest) values on psammal and the best (highest) values on coarse mineral substrates. Psammal sample showed the worst ecological quality expressed by the lowest EQR (Ecological Quality Ratio) value, most significantly differing from the multihabitat sample (Multiple Comparisons of Means: Dunnett Contrasts: –8.25, P < 0.01). We conclude that substrate types considerably influence selected metrics. Because of a relatively substantial proportion of psammal in some small Slovakian streams and its marginal influence on the overall ecological quality of the site, we suggest conduct further research addressing the effectiveness of its usage in the water management. [ABSTRACT FROM AUTHOR]

The information on both the catchment land use and catchment area has the potential to be adopted into the conservation and management of ponds. There have been, however, few attempts to describe the effects of land use acting at various spatial scales on ponds and the studies were restricted to specific categories of ponds. This paper presents a study on 92 ponds distributed over a broad range of environmental conditions in Central Europe. We combined an extensive field survey and a detailed analysis of sediment and water chemistry with GIS-derived data to estimate the relationship between the area of the ponds and the area of their catchments, and to assess the relationship between pond physico-chemical conditions and land use across multiple spatial scales. Relating the area of ponds to the area of their catchments, we found a significant positive relationship ( r = 0.72). Considering land use effects on pond conditions, catchment-scale land use was the only significant spatial extent influencing the physico-chemical conditions. Most notably, the proportion of intensively exploited land (arable land, urban areas) in the catchment scale was positively correlated with the deterioration of pond physico-chemical properties. The results of the study suggest that effective conservation of ponds cannot be achieved merely through the management of narrow buffer zones around them but should involve maintenance of less intensive land use within the whole catchment. Moreover, easily accessible catchment-scale GIS data could serve as a decision-support tool for cost-effective management strategies aimed at improving pond physico-chemical conditions. [ABSTRACT FROM AUTHOR]

Most functional feeding types are represented within the species rich group of aquatic chironomids. Thus, we hypothesized that different lake types and microhabitats within lakes would (1) host specific chironomid communities and (2) that the individual communities would show specific δC stable isotope signatures reflecting the prevailing origin of food source. To test our hypotheses, five lakes in southwest Greenland were investigated at a high taxonomic resolution and with detailed information on δC signature of the chironomids and of individual microhabitats (macrophytes, sediment, stones, and profundal). We found that there was a significant difference in δC between the chironomid assemblages of freshwater lakes and oligosaline lakes, while assemblages of the littoral microhabitats did not differ significantly. The δC of chironomids reflected the wide variety of habitat signals, particularly in the freshwater lakes. Our results indicate that many chironomid taxa are ubiquitous and are found in several microhabitats, suggesting that they can adjust their feeding strategy according to the habitat. The implication is that chironomid assemblage composition has only limited use as indicator of littoral microhabitats in the Arctic. On the other hand, the δC signature of fossil chironomids might have a potential as indicator of microhabitats in freshwater lakes. [ABSTRACT FROM AUTHOR]

In this study we aimed at comparing invertebrate diversity of high altitude lakes and ponds along hierarchical spatial scales. We compared local, among-site, and regional diversity of benthic macroinvertebrates in 25 ponds and 34 lakes in the Tatra Mountains, central Europe. The ponds showed significantly lower local diversity, higher among-site diversity and similar regional diversity than the lakes. The species–area relationships (SAR), habitat heterogeneity, and environmental harshness are assumed as drivers for the local diversity patterns. An ecological threshold separating pond and lake systems emerged at an area of 2 ha, where the SAR pattern changed significantly. Differences in species turnover between these systems were likely driven by greater environmental variability and isolation of the ponds. High altitude ponds neither significantly support greater regional diversity nor higher number of unique taxa than lakes. The higher among-site diversity of ponds relative to lakes highlights the relevance of ponds for regional diversity in mountain areas. [ABSTRACT FROM AUTHOR]

Chironomid assemblages of 22 artificial water bodies, mainly fountains, in two South American cities were surveyed. We found surprisingly low diversities, with a total of 11 taxa, averaging two taxa per site. The typical fountain assemblages mainly consisted of common species that have a wide distribution pattern and are tolerant to organic pollution. Also taxa independent of the natural aquatic sources, such as tap-water and semi-terrestrial species were represented. There was no significant difference between the taxa richness of the two S. American regions, however, the assemblage structures of the water bodies of Quito and Bogotá differed significantly. There was no correlation between sample similarities and distances among the sites either. The low number of taxa recorded can be attributed to the combination of naturally limited species pool and the heavy pollution in natural water bodies as colonization sources. [ABSTRACT FROM AUTHOR]

Littoral benthic macroinvertebrates were studied in three alpine lakes in the High Tatra Mountains (Slovakia) located at different elevations: 2157, 1940 (alpine zone) and 1725 m (sub-alpine zone). The study sites were selected in order to obtain a gradient in thermal regimes and particular organic matter (POM). Differences in the faunal composition of lakes were tested for the ability of these differences to indicate climatic changes, and species/taxa were identified that could be used for the purposes of monitoring and climate change assessment. Macroinvertebrates were sampled quantitatively during the ice-free seasons of 2000 and 2001, and lake surface water temperature (LSWT) and POM were measured. LSWT and POM were negatively correlated with elevation, whereas ice cover was positively correlated with elevation. A total of 60 oligostenothermic macroinvertebrate species/taxa were collected belonging to ten higher taxonomic groups. Statistical analysis showed trends in several biotic metrics with altitude. More specifically, there was a clear increase in the number of species/taxa, genera, and higher taxonomic groups, as well as an increase in the Shannon–Wiener diversity with decreasing altitude. On the contrary, evenness and density of benthic macroinvertebrates did not show any clear relationship with altitude. Gatherers of detrital particles dominated the assemblages’ trophic structures, but no distinct changes in the proportion of functional feeding groups along the altitudinal gradient were found. While the non-insect fauna of the lakes was rather uniform across the elevational gradient, the insect fauna composition was highly correlated with altitude, as confirmed by Detrended Correspondence Analysis. Aquatic insects, in particular chironomids and caddisflies, can therefore be used as good indicators of temperature changes. Our results suggest that under warmer conditions, non-insect benthic macroinvertebrates will remain more or less stable, while aquatic insects will undergo an increase in the number of thermophilic species typical for lower altitudes. These colonizers will increase the diversity of alpine lakes, while the extinction of cold stenothermal species will lead to impoverishment of the native fauna. An indirect impact on benthic macroinvertebrates through changes in food sources is likely, and changes in trophic structure of the littoral assemblages can be expected. [ABSTRACT FROM AUTHOR]

Diatom analysis was undertaken on a 200-year sediment record in an alpine lake (Popradské pleso, Tatra Mountains, Central Europe). Due to its remote character and well-documented human influence since the mid-nineteenth century, it allows a study of the relationship between anthropogenic pressures and diatom assemblages. Altogether, 122 diatom taxa of 40 genera were identified, and two major taxonomic shifts were revealed in the stratigraphic record. The timing of the first significant shift in ~ 1850 precludes the possibility of being caused by direct human activities, since according to historic documents there was neither continuous human presence nor grazing in the valley before that time. In addition, the direct effect of organic pollution early in the 1960s connected with the operation of a tourist hotel was not clearly reflected in the diatom signal. The diatom-inferred total phosphorus (DI-TP) reconstruction indicated the highest TP content well before the most direct wastewater pollution from a newly built hotel. There was a considerable effect of climate to diatom assemblage structure as well as diatom life forms. Our results suggest that direct organic pollution influenced the diatom communities less than expected, and the main driver of change was climate warming. We hypothesize that it is because of the short residence time of the lake, since it has both strong inlet and outlet, and it has been showed that the inlet had significant effect on benthic communities in the past. At the same time, fish manipulation could have been the reason for some fluctuation in DI-TP unrelated to climate and organic pollution. [ABSTRACT FROM AUTHOR]