Marek Polášek

• Ph.D.
• Researcher at Masaryk University

Aim To determine which riverine invertebrate traits respond consistently to anthropogenic impacts across multiple biogeographic regions. Location Europe. Time Period 1981–2021. Major Taxa Studied Riverine invertebrates. Methods We compiled a database of riverine invertebrate community time series for 673 sites across six European countries span...

More than half of the world’s rivers dry up periodically, but our understanding of the biological communities in dry riverbeds remains limited. Specifically, the roles of dispersal, environmental filtering and biotic interactions in driving biodiversity in dry rivers are poorly understood. Here, we conduct a large-scale coordinated survey of patter...

Exposure to synthetic chemicals, such as pesticides and pharmaceuticals, affects freshwater communities at broad spatial scales. This risk is commonly managed in a prospective environmental risk assessment (ERA). Relying on generic methods, a few standard test organisms, and safety factors to account for uncertainty, ERA determines concentrations t...

Freshwater macroinvertebrates are a diverse group and play key ecological roles, including accelerating nutrient cycling, filtering water, controlling primary producers, and providing food for predators. Their differences in tolerances and short generation times manifest in rapid community responses to change. Macroinvertebrate community compositio...

Humans impact terrestrial, marine and freshwater ecosystems, yet many broad-scale studies have found no systematic, negative biodiversity changes (for example, decreasing abundance or taxon richness). Here we show that mixed biodiversity responses may arise because community metrics show variable responses to anthropogenic impacts across broad spat...

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss¹. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity². Here, using 1,816 time series of fresh...

The lack of data from non-perennial rivers, which regularly cease to flow and dry up, poses a significant challenge in understanding river biodiversity. These dynamic ecosystems, accounting for over half of the global river network, remain understudied. To address this gap, we conducted a coordinated experiment and a metabarcoding approach on envir...

Typology systems are frequently used in applied and fundamental ecology and are relevant for environmental monitoring and conservation. They aggregate ecosystems into discrete types based on biotic and abiotic variables, assuming that ecosystems of the same type are more alike than ecosystems of different types with regard to a specific property of...

Biotic homogenization appears to be a global consequence of anthropogenic change. However, the underlying environmental factors contributing to homogenization are difficult to identify because their effects usually interact and confound each other. This can be the reason why there is very little evidence on the role of climate warming in homogeniza...

Aims and background Groundwater-dependent minerotrophic fens are globally threatened biodiversity hotspots. The supply of groundwater keeps their soil thermally stable and mitigates climatic extremes by thermal buffering. This stability has been shown to influence species composition variation at the between-site scale but has not been studied at...

Typology systems are frequently used in applied and fundamental ecology and are relevant for environmental monitoring and conservation. They aggregate ecosystems into discrete types based on biotic and abiotic variables, assuming that ecosystems of the same type are more alike than ecosystems of different types with regard to a specific property of...

Ongoing climate change and rising water demands are resulting in the increasingly frequent occurrence of stream drying, particularly in smaller streams in humid temperate climates. These streams are often situated in outlying regions with insuffcient wastewater treatment management leading to inconsistent inputs of nutrients into receiving water sy...

Thermal responses of spring insects are poorly understood, yet critically important because temperature regimes of spring habitats can be modified by climate warming. Here, we examined the species-specific responses of aquatic insects to variation in water temperature at 43 undamaged spring fens. Temperature was recorded for 1 year using datalogger...

Small streams in the temperate continental region of central Europe have been recently exposed to frequent drying. We investigated the effects of drying on clitellate communities in 25 small streams evenly distributed along the gradient of flow intermittence. We observed that the community exposed to both irregular and periodic drying could maintai...

Humans have severely altered freshwater ecosystems globally, causing a loss of biodiversity. Regulatory frameworks, like the Water Framework Directive, have been developed to support actions that halt and reverse this loss. These frameworks use typology systems that summarize freshwater ecosystems into environmentally delineated types. Within types...

Many studies examining plant and terrestrial invertebrate communities have revealed the high conservation potential of spoil heaps. On the other hand, the freshwater communities inhabiting post‐mining ponds within these human‐made habitats are almost unexplored. We focused on aquatic macroinvertebrate, zooplankton and phytoplankton communities in t...

River networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosystem services (e.g., supply drinking water and food, climate regulation) essential to sustaining human well-being. Climate change and increased human water use are causing more rivers and streams to dry, with devastating impacts on biodiversity and ecosy...

Rivers are dynamic ecosystems in which both human impacts and climate‐driven drying events are increasingly common. These anthropogenic and natural stressors interact to influence the biodiversity and functioning of river ecosystems. Disentangling ecological responses to these interacting stressors is necessary to guide management actions that supp...

With ongoing climate change and increasing water resource pressures, the knowledge and predictability of stream drying is essential for water management. However, the hydrological data for assessing the flow regime of temporary streams are often non-existent or scarce. The flow regime strongly affects stream ecological functioning and ecosystem pro...

Groundwater-dependent ecosystems represent globally rare edaphic islands of scattered distribution, often forming areas of regionally unique environmental conditions. A stable groundwater supply is a key parameter defining their ecological specificity, promoting also soil thermal buffering. Still, a limited number of studies dealt with the importan...

Intermittent stream research focuses mostly on pristine streams. The impacts of nutrient enrichment on invertebrate communities in these systems thus remains underexplored, especially in temperate climates. This study aimed to compare taxa survival during stream drying within pristine and nutrient-enriched sediment streambeds and to evaluate seedba...

The cover image is based on the Original Article Drying in newly intermittent rivers leads to higher variability of invertebrate communities, by Julie Crabot et al., https://doi.org/10.1111/fwb.13673.

• Aquatic invertebrate communities inhabiting intermittent rivers that are characterised by recurrent drying events (flow cessation or complete disappearance of surface water) often show rapid recovery upon flow resumption. Such rapid recovery is possible thanks to specific resistance and resilience traits that species adapted to river drying often...

Dispersal is an essential process in population and community dynamics, but is difficult to measure in the field. In freshwater ecosystems, information on biological traits related to organisms' morphology, life history and behaviour provides useful dispersal proxies, but information remains scattered or unpublished for many taxa. We compiled infor...

Section 4.6. Aquatic Plants

The influence of environmental factors on microbial community composition in a mountain river.-Acta Mus. Siles. Sci. Natur. 69: 75-88, 2020. Abstract: Microbial communities are known to be sensitive indicators for water pollution and biomonitoring assessment. In this study, we aimed at observation of microbial abundance and community composition in...

Motivation: Dispersal is an essential process in population and community dynamics but is difficult to measure in the field. In freshwater systems, relevant information on the dispersal of many taxa remains scattered or unpublished, and biological traits related to organisms morphology, life history and behaviour offer useful dispersal proxies. We...

Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of...

Groundwater‐dependent ecosystems are recognized as biodiversity hotspots being, apart many negative human impacts, highly threatened also by ongoing climate warming. Clitellata (Annelida) are dominant invertebrates of permanent fauna in spring habitats, representing a heterogeneous group including both specialized cold stenothermic and ubiquitous e...

Temporary streams are becoming increasingly common, but ecological responses to streambed drying are poorly characterized in the temperate continental region of central Europe. In addition, global research has focused on community responses to drying, whereas effects on individual populations remain unknown. We explored the population structure of...

Intermittent streams are naturally dominant landscape features of Mediterranean and arid regions, but also occur more and more in humid climates, such as in the Czech Republic. Organism abilities to cope with drying (i.e. resistance forms) have been quantified in naturally intermittent streams from Mediterranean and arid regions, in which long‐term...

Intermittent streams are naturally dominant landscape features of Mediterranean and arid regions, but also occur more and more in humid climates, such as in the Czech Republic. Organism abilities to cope with drying (i.e. resistance forms) have been quantified in naturally intermittent streams from Mediterranean and arid regions, in which long-term...

Many streams in the extensive Central European region have an intermittent flow regime. Conventional hydrological methods used to identify zero-flow conditions, and in particular drying events, have limited use when assessing large areas dominated by low-order streams. We developed a novel multimetric index to recognise antecedent stream drying bas...

Little is known about macroinvertebrate assemblages inhabiting aquatic-terrestrial transition zones, particularly at groundwater-fed wetlands. We studied diversity and vertical distribution of Dipteran assemblages in 27 spring fens characterised by variable groundwater chemistry ranging from acidic to extremely calcium rich. We sampled semiaquatic...

The genus Electrogena Zurwerra & Tomka, 1985 is a diverse mayfly group in the Western Palaearctic with a partially unclear taxonomy, even in well-examined areas such as Central Europe. Recently, one of the species belonging to this genus, Electrogena ujhelyii (Sowa, 1981), was identified as a complex of genetically and geographically separated spec...

The easy, fast and correct identification of species is a crucial aspect of biology and its applications, such as biomonitoring and nature conservation. One of the groups that are common but not easily to identify are mayflies at the larval stage. In recent years, many attempts to species identification using modern and non-traditional methods have...

We provide the first commented checklist of Armenian mayflies, based on all relevant literature and recent extensive sampling of 72 localities throughout Armenia during 2011, 2014, and 2015. Altogether 46 species are listed, eight of them reported from Armenia for the first time. One new species, Ecdyonurus (Ecdyonurus) eurycephalus sp. nov. is des...

Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES),which sometimes cease to flow and can dry completely, is largely ignored although theymay represent over half the global river network. Substantial amounts of terrestrialplant...

In the version of this Article originally published, the affiliation for M. I. Arce was incorrect; it should have been: ⁵Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany. This has now been corrected in the online versions of the Article.

An initial checklist of mayflies (Ephemeroptera) of Iran compiled based on the literature data and new data from the north-western Iran reported only 46 species and 25 genera.

An initial checklist of mayflies (Ephemeroptera) of Iran is compiled based on critical review of available literature data, complemented with new data from 38 localities of Gilan and Ardabil provinces. At present, altogether only 46 species and 25 genera are known from Iran, 18 species are reported as new to Iran in this study. Some previously publ...