Cold mountain stream chironomids (Diptera) of the genus Diamesa indicate both historical and recent climate change.

Chironomids of the genus Diamesa (Meigen, 1835, Diptera: Chironomidae) inhabit cold, oxygen-rich running waters. We have investigated the presence of Diamesa and other freshwater macroinvertebrates at 22 stream sampling sites in 3 European high mountain regions (the Central Pyrenees, the Ötztal Alps, and the Tatra Mountains) to establish suitable temperature conditions for Diamesa dominance. It has been generally accepted that their high abundance was linked to the presence of glaciers; however, we have shown that in the Tatra Mountains, where there are no glaciers, the conditions for the dominance of Diamesa species are created due to permanent snowfields, the geographical orientation of the valley and shading by the surrounding high peaks. The historical connection of Diamesa to glaciers was investigated from the paleolimnological records of subfossil chironomid assemblages from the Bohemian Forest, where glaciers disappeared before or during the Late Glacial period. As expected, water temperature seems to be the main driver of Diamesa distribution, and we determined that the relative abundance of Diamesa species was significantly higher at the sites with a mean July water temperature below 6.5 °C. The Diamesa-dominated stream communities seems to be endangered due to ongoing climate warming and this assumption is supported by our paleolimnological results from the Bohemian Forest lakes, where Diamesa has disappeared due to warming of lake inflows at the beginning of the Holocene. These findings strengthen the former suggestions that some Diamesa species could be used as an indicator for tracking recent environmental changes in vulnerable ecosystems of cold mountain streams.

Diversity and distribution of chironomids in Central European ponds.

Ponds are common freshwater habitats in the European landscape that substantially contribute to local and regional biodiversity. Chironomids often dominate invertebrate communities in ponds but are usually disregarded in ecological studies due to relatively complicated taxonomy and identification issues. We present a comprehensive overview of the chironomid diversity in 246 ponds spanning a wide range of conditions extending from the Pannonian Plain to the Carpathians. Altogether, we recorded 225 taxa including 192 species from six subfamilies (Podonominae, Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae). However, the chironomid taxa inventory is far from complete and about 16% of the total diversity of pond-dwelling chironomids remains undetected. Chironomid alpha diversity showed a significant unimodal pattern along the elevation gradient with the highest number of taxa per pond expected around 790 m a.s.l. Gamma diversity also peaked in mid-elevations (600-800 m), and the common chironomid taxa partitioned the 2100-m long altitudinal gradient relatively evenly. The heterogeneity of chironomid communities among ponds measured as beta diversity was significantly higher in elevations below 800 m. Temperature and the proportion of surrounding forests significantly influenced alpha diversity of chironomid communities, while urban land cover and pond size had no significant effect. Ponds with a mean annual air temperature of approximately 4.8°C and a low proportion of surrounding forests are expected to harbour the most diverse chironomid communities. Our study showed that chironomids represent a very diverse and often exceptionally rich group of pond-dwelling macroinvertebrates. Given the high diversity and broad range of occupied niches, chironomids should not be overlooked in pond ecology studies. On the contrary, they should be considered a potential model group.

Molecular and morphological characterisation of larvae of the genus Diamesa Meigen, 1835 (Diptera: Chironomidae) in Alpine streams (Ötztal Alps, Austria).

Diamesa species (Diptera, Chironomidae) are widely distributed in freshwater ecosystems, and their life cycles are closely linked to environmental variables such as temperature, water quality, and sediment composition. Their sensitivity to environmental changes, particularly in response to pollution and habitat alterations, makes them valuable indicators of ecosystem health. The challenges associated with the morphological identification of larvae invoke the use of DNA barcoding for species determination. The mitochondrial cytochrome oxidase subunit I (COI) gene is regularly used for species identification but faces limitations, such as similar sequences in closely related species. To overcome this, we explored the use of the internal transcribed spacers (ITS) region in addition to COI for Diamesa larvae identification. Therefore, this study employs a combination of molecular markers alongside traditional morphological identification to enhance species discrimination. In total, 129 specimens were analysed, of which 101 were sampled from a glacier-fed stream in Rotmoostal, and the remaining 28 from spring-fed streams in the neighbouring valleys of Königstal and Timmelstal. This study reveals the inadequacy of utilizing single COI or ITS genes for comprehensive species differentiation within the genus Diamesa. However, the combined application of COI and ITS markers significantly enhances species identification resolution, surpassing the limitations faced by traditional taxonomists. Notably, this is evident in cases involving morphologically indistinguishable species, such as Diamesa latitarsis and Diamesa modesta. It highlights the potential of employing a multi-marker approach for more accurate and reliable Diamesa species identification. This method can be a powerful tool for identifying Diamesa species, shedding light on their remarkable adaptations to extreme environments and the impacts of environmental changes on their populations.

Energy status of chironomid larvae (Diptera: Chironomidae) from high alpine rivers (Tyrol, Austria).

Chironomids (non-biting midges) inhabit almost every wet or semi-wet continental environment on Earth with probably 10,000 different species. Species occurrence and composition are undoubtedly limited by environmental harshness and food availability being reflected in their energy stores. Most animals store energy as glycogen and lipid. They enable the animals to survive adverse situations and to continue growth, development, and reproduction. This general statement is also true for insects and also particularly true for chironomid larvae. The rationale behind this research was, that probably any stress, any environmental burden, and any harmful influence increases the energy requirement of individual larvae depleting energy stores. We developed new methods to measure the glycogen and lipid content in small tissue samples. Here we show how to apply these methods to single chironomid larvae to demonstrate their energy stores. We compared different locations of the high Alpine rivers along harshness gradient densely populated and dominated by chironomid larvae. All samples show very low energy stores without any major differences. We found glycogen concentrations below 0.01% of dry weight (DW) and lipid concentrations below 5% of DW irrespective of the specific sampling point. These values are among the lowest ever observed in chironomid larvae. We demonstrate that individuals living in extreme environment are stressed leading to reduced energy stores in their bodies. This appears to be a general feature of high altitude regions. Our results provide new insights and a better understanding of population and ecological dynamics in harsh mountainous areas, also in view of a changing climate.

Subfossil chironomids (Diptera, Chironomidae) of lakes in the Tatra Mountains: an illustrated guide.

Here we present a summary of subfossil chironomids (Diptera: Chironomidae) found in the surface sediments of 52 Tatra Mts. lakes (Slovakia, Poland). Head capsules of 73 morphotypes of 5 subfamilies are described and illustrated. In addition to the previously documented subfossils by Brooks et al. (2007), we present 15 new morphotypes: Diamesa Tatra-type A, Diamesa Tatra-type B, Pseudodiamesa branickii-type, Pseudodiamesa nivosa-type, Pseudokiefferiella parva, Brillia bifida-type, Cricotopus (Paratrichocladius) skirwithensis-type, Cricotopus (Cricotopus) tremulus-type, Cricotopus/Orthocladius I, Eukiefferiella brevicalcar-type, Eukiefferiella claripennis-type B, Orthocladius (Orthocladius) dentifer-type, O. (Mesorthocladius) frigidus, Orthocladius (Euorthocladius) sp. and Tanytarsini indet. Most of these types have possibly broad distribution patterns in Europe. We believe that due to specific features of each region, this paper will serve as a helpful manual for limnologists and paleolimnologists working not only in the Tatra Mts. but also in the whole Carpathian region.

Chironomids (Insecta, Diptera, Chironomidae) from alpine lakes in the Eastern Carpathians with comments on newly-recorded species from Ukraine.

BACKGROUND: The first summarising checklist of Ukrainian Chironomidae (Insecta, Diptera) consisted of 302 species. Compared to other European countries, it is obvious that the real chironomid diversity of Ukraine has not been fully documented and greater effort is needed to discover the actual richness of this family. Thus, our survey focused on the chironomid fauna of some alpine lakes situated above the treeline in the Ukrainian Carpathians (a part of the Eastern Carpathians) aiming to contribute to the knowledge of the Ukrainian chironomid fauna and create the basis for more comprehensive neo- and palaeolimnological studies of these, regionally, little-known ecosystems. NEW INFORMATION: In total, 34 species/taxa, belonging to 22 genera and 4 subfamilies were collected in June 2019. Ten species were recorded for the first time in Ukraine: Zavrelimyia melanura, Acamptocladius reissi, Cricotopusspeciosus, Cricotopuscurtus, Heterotrissocladius marcidus, Orthocladius dentifer, Psectrocladiusoligosetus, Polypedilumuncinatum, Paratanytarsus laccophilus and Tanytarsus bathophilus. The occurrence of six species previously considered as "doubtfully present" in Ukraine was finally confirmed. Generally, the surveyed lakes have a unique composition of chironomids consisting of a mixture of species typical for cold alpine lakes and acidic ponds situated at lower altitudes.

A preliminary checklist of Chironomidae (Diptera) from Albania with first records for the Balkan Peninsula.

The Chironomidae of Albania have so far received limited attention and only 39 species have been recorded prior to the present study. Here we bring the results of random and non-intensive samplings of chironomid pupal exuviae and adults, at five localities in 2012, that provided 55 species and 5 additional taxa, with 51 being new for the Albanian fauna, out of which 7 were new for the Balkan Peninsula. In addition to that, we present a preliminary checklist of Chironomidae based on the data from Fauna Europaea complemented by the results of the recent investigation. The catalogued fauna now contains 85 species in 44 genera and 6 sub-families.

Origin and behavior of radionuclides in sediment core: a case study of the sediments collected from man-made reservoirs located in the past mining region in Central Slovakia.

The analyzed sediments were taken from the man-made reservoirs (Velka Richnava, Rozgrund and Vindsachta) located in an area intensively mined for polymetallic ores since the end of the eleventh century (Banska Stiavnica region, Central Europe). The aims of this study were to determine the radioactivity of natural (226Ra, 228Th, 210Pb) and artificial (137Cs and 241Am) radionuclides, compare the radionuclides' distribution, and indicate the correlation of radioisotopes and their origin related to sediment properties. Two analytical techniques were used. 228Th, 226Ra, 241Am, and 137Cs were measured by means of gamma spectrometry and 210Pb was determined by its daughter radionuclide 210Po using alpha spectrometry. The results showed that the highest mean level of 226Ra (42.6 Bq·kg-1), 228Th (49.7 Bq·kg-1) and 210Pb (75.2 Bq·kg-1) was in the sediments collected from Rozgrund. The radioactivity of 137Cs and 241Am were present at a higher level in the layer related to Chernobyl (1986) accident and nuclear weapon test (1950/1960). The distribution of natural radionuclides was quite similar in all reservoirs. Chemometric analysis confirmed the radionuclides' origin and correlation between the analyzed parameters.

Reconstructing the Trophic History of an Alpine Lake (High Tatra Mts.) Using Subfossil Diatoms: Disentangling the Effects of Climate and Human Influence.

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.

Lake biota response to human impact and local climate during the last 200 years: A multi-proxy study of a subalpine lake (Tatra Mountains, W Carpathians).

Element content, loss-on-ignition, chironomid analysis and (210)Pb dating were applied on a sediment core from a subalpine Tatra lake (Popradské pleso) to reveal the response of aquatic biota to eutrophication induced by human activities in the lake catchment. The lead dating indicates that the 0-8 cm section of the core represents the past ca 200 years, ending at ~1814 AD. Comparing the key changes of the proxies with human activities that are historically well documented, four phases of the recent lake development were distinguished: (1) a pre-tourism phase, (2) a phase of increasing touristic activity and early cottage development, (3) a phase of eutrophication, and (4) a phase of post-eutrophication. Neither touristic activity, nor early cottage development around the lake (1st and 2nd phases) had considerable influence on the chironomid assemblage structure or organic content of the lake. The most significant change both in chironomid assemblage structure and loss-on-ignition occurred during the 3rd phase, when a big tourist hotel was built close by the lake and started contaminating it via direct wastewater input. However, the structure of the chironomid assemblage has not changed significantly over time and the dominating taxa remained the same during the whole period. Parallel with the nutrient signal of the paleo assemblage, a secondary signal has been identified as the ratio of rheophilic taxa on total abundance that did not correlate with the sediment's organic content, and is most likely driven by local climatic oscillations. Changes of most of metal elements concentrations reflected rather bigger scale changes of industrial activities than local scale human disturbances. Our results indicate that hydromorphological properties can moderate the impact of organic pollution on the lake biota.