Free-living aquatic nematodes are abundant, diverse and of general environmental importance. However, knowledge of species distributions of both marine and freshwater nematodes is sparse. Species distribution data are crucial for evaluating environmental impacts from human activities and to conduct integrated nematode community assessments. Basic knowledge on taxonomy and species descriptions is lacking for many regions due to decreasing taxonomic expertise, yet it is essential for biodiversity research and for building molecular sequence libraries for the application of methods such as environmental DNA. In order to encourage and facilitate taxonomic and descriptive work on this understudied group, we present here a framework for nematode species description. We begin by providing a brief overview of nematology history, then provide suggestions of microscopic methods that should be used and provide a list of characters essential for morphometric species descriptions. Finally, we briefly discuss common molecular sequencing approaches that are commonly used in nematode taxonomic literature.

Environmental DNA (eDNA) metabarcoding (parallel sequencing of DNA/RNA for identification of whole communities within a targeted group) is revolutionizing the field of aquatic biomonitoring. To date, most metabarcoding studies aiming to assess the ecological status of aquatic ecosystems have focused on water eDNA and macroinvertebrate bulk samples. However, the eDNA metabarcoding has also been applied to soft sediment samples, mainly for assessing microbial or meiofaunal biota. Compared to classical methodologies based on manual sorting and morphological identification of benthic taxa, eDNA metabarcoding offers potentially important advantages for assessing the environmental quality of sediments. The methods and protocols utilized for sediment eDNA metabarcoding can vary considerably among studies, and standardization efforts are needed to improve their robustness, comparability and use within regulatory frameworks. Here, we review the available information on eDNA metabarcoding applied to sediment samples, with a focus on sampling, preservation, and DNA extraction steps. We discuss challenges specific to sediment eDNA analysis, including the variety of different sources and states of eDNA and its persistence in the sediment. This paper aims to identify good-practice strategies and facilitate method harmonization for routine use of sediment eDNA in future benthic monitoring.

The Balkan Peninsula is a biodiversity hotspot and hosts numerous mountain lakes, which offer a refuge for a multitude of species. However, previous pristine habitats have been deeply affected by anthropogenic change, such as non-native fish introductions, which calls for multi-species considerations in the last remaining unaltered habitats. We carried out abiotic measurements and biodiversity assessments in two neighbouring alpine lakes, Lakes Leqinat and Drelaj in the Bjeshkët e Nemuna National Park in Kosovo, in August 2018. Lake Leqinat is a permanent, stratified water body and exhibits weak oxygen depletion below 3 m. Phytoplankton was dominated by chrysophycean, cryptophycean and chlorophycean algae. Zooplankton consisted of five rotifer species and Daphnia longispina. A mark-recapture experiment yielded a population of alpine newts (Ichthyosaura alpestris) of nearly 4 000 adult individuals. In contrast, cold water from the surrounding karst seeps into Lake Drelaj, which is a well-oxygenated temporary lake. Hence phytoplankton and zooplankton biomasses were considerably lower than in Lake Leqinat. Phytoplankton was dominated by cryptophycean, chlorophycean, and bacillariophycean algae. Zooplankton consisted of the diaptomid copepod Mixodiaptomus tatricus, the cladoceran Daphnia rosea, and the anostracan Chirocephalus diaphanus. Conservation efforts should ensure that Lake Leqinat remains unstocked as introduced fish would probably destroy the natural community. Research eco.mont – Volume 13, Number 1, January 2021 ISSN 2073-106X pr int vers ion – ISSN 2073-1558 onl ine vers ion: ht tp://epub.oeaw.ac.at/eco.mont ht tps://dx.doi.org/10.1553/eco.mont-13-1s12 12

Bioindication has become an indispensable part of water quality monitoring in most countries of the world, with the presence and abundance of bioindicator taxa, mostly multicellular eukaryotes, used for biotic indices. In contrast, microbes (bacteria, archaea and protists) are seldom used as bioindicators in routine assessments, although they have been recognized for their importance in environmental processes. Recently, the use of molecular methods has revealed unexpected diversity within known functional groups and novel metabolic pathways that are particularly important in energy and nutrient cycling. In various habitats, microbial communities respond to eutrophication, metals, and natural or anthropogenic organic pollutants through changes in diversity and function. In this review, we evaluated the common trends in these changes, documenting that they have value as bioindicators and can be used not only for monitoring but also for improving our understanding of the major processes in lotic and lentic environments. Current knowledge provides a solid foundation for exploiting microbial taxa, community structures and diversity, as well as functional genes, in novel monitoring programs. These microbial community measures can also be combined into biotic indices, improving the resolution of individual bioindicators. Here, we assess particular molecular approaches complemented by advanced bioinformatic analysis, as these are the most promising with respect to detailed bioindication value. We conclude that microbial community dynamics are a missing link important for our understanding of rapid changes in the structure and function of aquatic ecosystems, and should be addressed in the future environmental monitoring of freshwater ecosystems.

Nematodes are present in all types of lentic and lotic habitats. They are abundant, functionally diverse and serve as bio-indicators to assess water quality and environmental changes. However, our knowledge of freshwater nematodes is hampered by their small body size, the need for processing and mounting on microscopic slides for observation at high magnification and the dearth of identification keys, especially at higher taxonomic levels. Therefore, here we provide separate identification keys at order, family and genus level, as far as possible, for those freshwater nematodes from the Palaearctic region, excluding parasites of vertebrates inhabiting freshwater habitats as eggs or within an intermediate host. In total, the identification keys deal with 87 nematode families and 259 genera. We include illustrated information on their morphology, terminology and on material preparation and sample preservation.

Effective identification of species using short DNA fragments (DNA barcoding and DNA metabarcoding) requires reliable sequence reference libraries of known taxa. Both taxonomically comprehensive coverage and content quality are important for sufficient accuracy. For aquatic ecosystems in Europe, reliable barcode reference libraries are particularly important if molecular identification tools are to be implemented in biomonitoring and reports in the context of the EU Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). We analysed gaps in the two most important reference databases, Barcode of Life Data Systems (BOLD) and NCBI GenBank, with a focus on the taxa most frequently used in WFD and MSFD. Our analyses show that coverage varies strongly among taxonomic groups, and among geographic regions. In general, groups that were actively targeted in barcode projects (e.g. fish, true bugs, caddisflies and vascular plants) are well represented in the barcode libraries, while others have fewer records (e.g. marine molluscs, ascidians, and freshwater diatoms). We also found that species monitored in several countries often are represented by barcodes in reference libraries, while species monitored in a single country frequently lack sequence records. A large proportion of species (up to 50%) in several taxonomic groups are only represented by private data in BOLD. Our results have implications for the future strategy to fill existing gaps in barcode libraries, especially if DNA metabarcoding is to be used in the monitoring of European aquatic biota under the WFD and MSFD. For example, missing species relevant to monitoring in multiple countries should be prioritized for future collaborative programs. We also discuss why a strategy for quality control and quality assurance of barcode reference libraries is needed and recommend future steps to ensure full utilisation of metabarcoding in aquatic biomonitoring.

A new geological epoch has begun—the Anthropocene. Huge anthropogenic transformations of terrestrial landscapes over the past five decades have forced its declaration. Exploring of interaction of humans with nature in general, and with landscapes in particular, can be characterised properly by the terms ‘landscape research’ and ‘landscape science’. Landscape science has been a traditional scientific discipline of geography. This is the case in Russia, whilst the terms geo-ecology and landscape ecology have become established in the English-speaking scientific community. As landscapes are multifunctional, highly complex systems, landscape research is a platform for disciplinary, interdisciplinary and transdisciplinary research. Landscape research in the Anthropocene must aim to combine landscape sustainability with high quality and productivity. This mission is in accord with the Sustainable Development Goals of the United Nations and the provisions of the Landscape Convention of the European Council. It includes halting landscape degradation, developing cultural landscapes and maintaining semi-natural landscapes. Clean water and air, fertile and healthy soils for food and other ecosystem services and a green and biodiverse environment are attributes of landscapes for the survival and well-being of humans in coexistence with nature. Landscape research must generate knowledge, innovations and responsible decision rules for achieving these aims. Big data gathering and scenario modelling are important for knowledge generation in a globalised world. International long-term experiments, observatories and monitoring systems will deliver data for comprehensive ecosystem models and decision support systems. Technical innovations must be imbedded in cultural solutions for the evolvement of landscapes. Springer International’s new book series ‘Innovations in Landscape Research’ aims to support better understanding, monitoring and managing landscapes. It contains a multitude of approaches and data. Some focus is on technical innovations for agri-environmental monitoring, on land and water management and its implications for landscape sustainability. Authors present novel tools for ecosystem modelling and forecasting of landscape processes, and on creating knowledge, rules and approaches for handling the multifunctionality of landscapes. The coming book series may serve as a knowledge, data and communication basis for informed decisions regarding the development of landscapes. It will enlarge our horizon and field of action by building bridges between scientific communities, scientific disciplines, and researchers and citizens.

Research Infrastructures (RIs) are facilities, resources and services used by the scientific community to conduct research and foster innovation. LifeWatch ERIC has developed various virtual research environments, which include many virtual laboratories (vLabs) offering high computational capacity and comprehensive collaborative platforms that supporting the needs of digital biodiversity science. Over its 250 years of history, the taxonomic research community has developed a system for describing, classifying and naming taxa across multiple levels. For the marine biota, taxonomic information is organized and made publicly available through the World Register of Marine Species (WoRMS) that records more than 250,000 described valid species. Although scientists tend to assign an equal status (in terms of contribution to overall diversity) to each taxon used in taxonomy, biogeography, ecology and biodiversity, the question “are all taxa equal?” has never been tested at a global scale. We present evidence that this question can be addressed by applying relatedness indices (Taxonomic Distinctness) over the entire WoRMS metazoan tree. The RvLab, developed by the LifeWatchGreece RI, operating on a high-performance computer cluster, has been used to meet the high computational demands required for such an analysis at a global scale.

In Austria all general types of aquifers (porous, karstic and fractured) are present and are subject of hydraulic and hydrochemical investigations. However, in hydrogeological research it is a still widely neglected fact that groundwater flow is not only a flux of water, chemicals and heat within lithological units but that groundwater bodies may also act as habitats with very particular conditions for their inhabitants. In general groundwater inhabitants require three things: a place to live, oxygen and energy or food, respectively. Thus, the living conditions of groundwater animals are directly connected to hydrological and geomorphological conditions on a regional scale, and on a local scale, lithological and structural properties that control hydrogeological parameters such as porosity and hydraulic conductivity, recharge mechanisms and flow dynamics.In this paper we view Austrian hydrogeology from the perspective of groundwater fauna in order to elucidate the connection between the hydrogeological conditions and biological patterns. A brief review of groundwater biology research in general and specifically in Austria, revealed that crustaceans are basically in the focus of groundwater research while other common groundwater dwellers, such as free-living nematodes, are less studied similarly. Porous aquifers are comparably well investigated by groundwater biologists, while fractured aquifers have rarely been considered as habitats to date.Due to the complex hydrogeological situation in Austria, with a greater portion of fractured and karstic aquifers, a systematic biological survey considering hydrogeological aspects may lead to a pronounced progress for the both disciplines, hydrogeology and groundwater biology. For hydrogeological purposes, the studies may provide the basis for using groundwater species (similar to the established method of using stable isotopes) as natural tracers in future studies. From the biological perspective, progress in the understanding of complex habitat-biota relations is expected to result from the investigation of hitherto unknown habitats. In addition, such a survey would not only be an important contribution to biodiversity and biogeography in Austria, it would also promote groundwater research in a broader context, such as the need to protect groundwater as a valuable service providing system (e.g. water quality).Preliminary results from six test sites distributed to four different geological settings (Quaternary basin fill, Flysch-Zone, Northern Calcareous Alps and the Central Crystalline Zone within the Alps) show evidence for a link between the hydrogeological conditions and the present biological assemblages. However, a systematic survey is still required to understand which environmental factors mainly govern live in Austrian aquifers.

The subterranean part of the water cycle takes place in three different types of groundwater bodies: (1) unconsolidated sediments, (2) karstic aquifers and (3) fractured hard rock aquifers. Basically, different aquifer types require different investigation methods. However, the physico-chemical properties of groundwater can aid in the understanding of flow history and aquifer dynamics of each aquifer type. Although groundwater biology is sensitive to hydrochemistry, water temperature and flow velocity, the possible benefits of groundwater animals as hydrogeological agents' is still rarely considered by hydrogeologists. The main research focus of hydrogeologists and groundwater biologists is shallow groundwater bodies in unconsolidated sediments and karst aquifers. Fractured hard rock aquifers are still poorly considered by both disciplines. This commentary has three purposes: (1) to show the special characteristics of fractured hard rock aquifers in comparison to porous and karst groundwater bodies, and to describe the resulting methological gap hydrogeologists face when investigating such aquifer types; (2) to give an overview of current groundwater biological research with its focuses and shortcomings, including an introduction of rarely known but common groundwater inhabitants, namely free-living nematodes; and (3) to suggest a combination of methods, supported by a hypothetical example, and the possible benefits this combined knowledge from hydrogeologists and groundwater biologists can bring to both disciplines. Copyright (c) 2014 John Wiley & Sons, Ltd.

Glacier-fed rivers are among the most sensitive and endangered habitat types nowadays. Their upper reaches are located within areas of economic interest (e.g. skiing and glacier skiing, hydropower generation), but also within protected areas such as, for example, National Parks worldwide (e.g. Hohe Tauern, Pyrenees, Rocky Mountains). The majority of glacial river studies has focused on the macrozoobenthos. Thus, this study presents a comparison of the widely neglected stream micro-and meiobenthos (MMB) among different glacial-fed stream reaches driven by two different glacier catchments: the Möll River Catchment (MC) and the Kleinelendbach stream catchment (KC). The catchments differ in catchment and glacier area, and glacier retreat patterns. The stream reaches comprised different habitat types such as the glacier source and extreme harsh glacial stream main channels, but also benign, less glacier influenced side channels. Their ages (years since deglacierization) ranged from 0 to ~ 150 years. They were within the protected area of the Hohe Tauern National Park. The regional diversity of the MMB (taxa numbers of fungi, algae, protists, nematodes, rotifers, invertebrates) was generally high in both catchments (MC: 270; KC: 291). The local (stream reach) diversity was also relatively high, but taxa numbers varied considerably between reaches and ranged from 64 – 195. Highest taxa numbers were recorded for benign stream habitats of the KC (195) and the MC (172). The latter was within the Sandur area downstream the margin of the Pasterze glacier. The benign sites represented not only local hot spots of diversity but also hot spots of ecological functionality with regard to the broad spectrum of abundant organisms, comprising primary producers (autotrophic flagellates, cyanobacteria, diatoms and other algae), decomposers (bacteria, fungi) and diverse consumers (heterotrophic flagellates, protists, nematodes, rotifers, copepods, tardigrades). ANOSIM resemblance analysis revealed similarity of fungi, protists and rotifers, and dissimilarity of bacteria, flagellates, diatoms and nematodes between the different stream reaches. The perspectives of ongoing glacier retreat and expected alterations of glacial-fed rivers may have various consequences for the MMB: thermal and hydrological changes along main river channels will represent adaptive challenges to these organisms, whereas drying of side arms and surrounding wetlands will lead to regional extinctions. The latter would represent an enormous loss of diversity that may affect ecological processes and services of alpine areas. But actual habitat changes and their effects on biodiversity as well as on ecological processes and services of alpine glacier catchments clearly need further investigations.

Ongoing glacial retreat is expected to lead to numerous changes in glacier-fed rivers. This study documents the development of community composition of the hitherto widely neglected micro- and meiobenthos (MMB: bacteria, fungi, algae, protists, and meiofauna) in glacier rivers in response to the distinct habitat conditions driven by different stages of (de)glacierization. Our model is based on the glacier catchments of the Möll River (MC) and Kleinelendbach stream (KC), in the Austrian Alps, with 60% and 25% glacierization and glacier retreats of 403 and 26 m, respectively, since 1998. Analyses of overall catchment diversity and resemblance patterns showed that neither intense glacierization nor rapid deglacierization were predominant MMB determinants. This was ascribed to the specific environmental conditions at the MC, where the rapidly retreating Pasterze glacier has formed a harsh unstable proglacial, but also a benign floodplain area, with the former suppressing and the latter supporting the structural development of the MMB. Comparisons of similarly aged riverine habitats of the MC proglacial and the KC main channel further evidenced developmental suppression of the MMB (64 taxa) by the rapidly retreating MC glacier, unlike the moderate glacial retreat in the KC (130 taxa). Habitat conditions interacting with melt periods explained the differences in MMB resemblance patterns, which themselves differentially reflected the spatiotemporal habitat settings imposed by the different glacier activities. The varying glacial influences were represented by a glaciality index (GIm) based on water temperature, electrical conductivity, and stream bed stability. The taxonomic richness of nematodes, rotifers, algae, and diatoms was distinctly related to this index, as were most MMB abundances. However, the strongest relationships to the GIm were those of nematode abundances and maturity. Our observations highlight the intense response of the MMB to ongoing glacier retreat and the utility of a simple index to reveal such patterns.

Free-living nematode communities were investigated at four morphologically different reaches along the River Wien, Austria. A near natural (NN) reach, two impounded reaches of different size (small and large: SI, LI) and a restored reach (RR) were sampled in autumn, winter, spring and summer (2004-2005). A total of 4144 individuals were counted and comprised 78 species. Nematodes of the impounded sites contributed least (5% at SI) and most (60% at LI) to the total fauna. Mean site abundances (ind./10 cm(2)) were 68, 27, 10 and 1 at RR, NN, LI and SI, respectively. Species diversity ranged from 1.59 at LI to 2.16 at RR. Bacterivorous nematodes dominated all sites (>50%); only algivorous Chromadoridae represented a high percentage contribution (46%) at LI. Based on this high portion, the maturity index (MI 1-5) was highest at this site (2.61). The MI indicated status of good water quality for the NN (2.5). The relatively low MI (2.10) and the high portion of cp1 Secernentea (14%) reflect the status of critical pollution at the restored site. The patterns of average taxonomic distinctness (ATD) did not optimally reflect habitat quality; a better descriptor of degraded river habitats seems to be the variation of taxonomic distinctness (VTD) in this study. In conclusion, the MI seems to be a better descriptor of pollution and the VTD of morphological degradation.

This study documents the spatiotemporal distribution of free-living nematodes in glacial-fed river reaches (Moll River, Austrian Alps), which is a widely neglected topic in glacial-fed stream research. Benthic nematodes of the meta- and hypokryal, in a lotic reach within a glacially formed floodplain and in the glacio-rhithral, were investigated in spring, summer, and autumn 2005. The overall nematofauna was diverse and dense with 77 species, H' of 2.7, and mean abundance of 86 individuals per 10 cm(2). Nematode community parameters were significantly influenced by sites, but not by seasons. At the kryal sites, nematode overall mean abundances slightly increased from the metakryal (8 ind. per 10 cm(2)) to the hypokryal (11 ind. per 10 cm(2)), but species number decreased (from 15 species to 6 species). Nematodes became more dense and diverse in both the glacio-rhithral (overall mean: 49 ind. per 10 cm(2); 52 total species) and the floodplain reach (overall mean: 251 ind. per 10 cm(2); 65 total species). Species composition and dominant species differed among the four sites. Deposit feeders represented the dominant feeding type at each site. The lowest maturity index reflected the harsh character of the recently deglacierized meta- and hypokryal sites.

Females and males of a new species of the genus Mononchus were found in an alpine, glacial floodplain reach (2073 m a.s.l.) in the Grossglockner region (Hohe Tauern National Park; Austria). Females of Mononchus sandur n. sp. are medium sized (1.5-1.8 mm) with body diam. of 45-65 mu m. The buccal cavity is 28-35 x 13-15 mu m in size with the dorsal tooth located 65-77% from the buccal cavity base. The distinct amphid openings (4 mu m) are located 11 mu m posterior to the head and anterior to the dorsal tooth apex. The general appearance of the female is characterised by the shape of the tail with its combination of length and slenderness (224-306 mu m; c' = 7.2-10.8). Males of M. sandur n. sp. are very similar to females with the exception of a shorter tail (147-159 mu m). Males have 16 and 18 preanal supplements, 57-68 mu m long spicula and 11-14 mu m long gubernaculum. Morphometric measurements and ratios were determined for 20 females of M. sandur n. sp., M. truncatus and M. aquaticus, all co-occurring in the floodplain reach. One-way analysis of variance revealed that M. aquaticus, M. truncatus and M. sandur n. sp. differ significantly in 18 out of 20 morphometric traits. A cluster analysis of ten morphomettic traits was done to allocate and separate the measurements of the 60 females. Three distinctly separate clusters arose. By calculating the Kappa coefficient (K), it could be shown that the partitioning of individuals in these three clusters was in complete accordance with the species determination (K = 1; P < 0.0001).