Jana Schenková

The distribution of chironomid larvae and oligochaetes within a stony-bottomed river stretch: the role of substrate and hydraulic characteristics

Combined oligochaete and chironomid data were analyzed to search for main gradients and the separate data sets were analyzed to identify the most important variables determining the structure of the communities. Preferences for particular hydraulic conditions, expressed as Froude number, were calculated for 29 most abundant taxa. The results of Correspondence Analysis (CA) indicated that the main gradient in the data could be explained by hydraulic conditions and, inversely, by the amount of sedimented particulate organic matter (POM). The second CA axis probably reflected the quantity of the available food and space resources. Canonical Correspondence Analysis (CCA) showed the amount of sedimented POM as the most important variable explaining 21 and 24 % of the variance in the oligochaete and chironomid data respectively. Among the other variables, the occurrence of aquatic vegetation, variability of nearbottom current velocity and substrate roughness were the most important.

Habitat preferences of aquatic Oligochaeta (Annelida) in the Rokytná River, Czech Republic - a small highland stream

Research was carried out to determine aquatic oligochaete habitat preferences in the Rokytna River (Thaya River basin), a sixth order highland stream in the Czech Republic during the period of April 1999–April 2001. Quantitative samples were collected and current velocity and basic physico-chemical variables were measured monthly in four typical habitats in the Rokytna River. During this study, 28, 842 individuals representing 44 oligochaete species or higher taxa were collected. Temporal variability of proportional occurrence of trophic groups found on selected habitats (gathering collectors and grazers) was analysed. Habitat preferences of oligochaete species were evaluated by Canonical Correspondence Analysis (CANOCO). Biochemical oxygen demand (BOD) and nitrate (NO 3 − ) ion concentration were the most important variables explaining the distribution of Oligochaeta along the first axis. Current velocity (at 40% of the depth) and presence of oligochaetes associated with the habitat where gravel bars never formed were the most important variables along the second axis. Both axes were correlated with the temperature, reflecting the sampling in summer along the first axis and sampling in late spring along the second axis. The amount of organic matter (BOD) and concentrations of NO 3 − ions represented both oligochaete food source and decomposition products contributing to the growth of algae. Current velocity and preferred habitat explained the spatial pattern of oligochaete distributions.

Oligochaeta of the Morava and Odra River basins (Czech Republic): species distribution and community composition

The oligochaete fauna of 57 small streams of the Morava and Odra River basins, Czech Republic, was studied during 1997 and 1998. TWINSPAN and CCA (CANOCO) were used to characterize the relationship between oligochaete species, habitat diversity and environmental variables. Chemical oxygen demand (COD), water hardness, NO3−–N, Ca2+, Mg2+, altitude, and substrate type were found to be the primary factors influencing the distribution of aquatic Oligochaeta.

Seasonal dynamics of Bythonomus lemani and Bothrioneurum vejdovskyanum (Oligochaeta, Annelida) in relation to environmental variables

The seasonal dynamics of Bythonomus lemani (Lumbriculidae) were studied for the first time and the knowledge of Bothrioneurum vejdovskyanum (Tubificidae) was extended based on four quantitative samples of oligochaetes taken monthly in the Rokytná River (Czech Republic) during a two-year study (April 1999–April 2001). The influence of water temperature, velocity, depth, discharge, pH, conductivity, dissolved oxygen amount and biochemical oxygen demand (BOD) on their life cycles was evaluated. Habitat preferences of the juvenile and adult stages were recorded. Time series analysis was used to determine the worm densities, seasonality and trends. For Byth. lemani one distinct reproduction cycle per year was found and this was regulated by temperature, while Both. vejdovskyanum showed a one-year cycle not significantly dependent on measured environmental variables. The overall trend was an increase in density for Byth. lemani and a decrease in density for Both. vejdovskyanum. Byth. lemani showed a significant negative correlation between the trend of its density and BOD concentration.

Diversity patterns of aquatic specialists and generalists:contrasts among two spring-fen mesohabitats and nearby streams

Abstract Habitat specialists and generalists are known to differ in their width of environmental tolerance and their representation can vary along with the ecological contrast of habitats. In this study we explore factors shaping patterns of species richness and abundance of aquatic macroinvertebrate habitat specialists and generalists at isolated spring fens, separately for spring patch and spring brook mesohabitats at each site. We also examined habitat contrast of these unique island-like communities by the comparison of spring fen specialists and habitat generalists shared between the two spring fen mesohabitats and the nearest stream to each of 13 selects fen sites. Aquatic macroinvertebrates (Clitellata, Ephemeroptera, Plecoptera, Trichoptera, and Diptera) were investigated at 62 isolated spring fens, with 357 taxa identified in more than 172,000 individuals collected. We found that specialists experienced a stronger relation to local environmental conditions (i.e. the amount of dissolved oxygen and water conductivity) at both spring mesohabitats than generalists, primarily responding to fen habitat size. In contrast, responses of species abundances at spring patches and spring brooks differed as the abundances were controlled by the amount of oxygen in spring patches and by habitat size in spring brooks. Based on Trichoptera and Diptera assemblages we found a similar contrast between both spring fen sites and nearby streams. Our results suggest a higher resilience of specialist populations in well oxygenated sites and their competitive advantage over generalists at these sites, which stresses the importance to prevent any significant decrease of oxygenation (e.g., by eutrophication or drainage), especially in spring patches.

Spring-fen habitat islands in a warming climate: Partitioning the effects of mesoclimate air and water temperature on aquatic and terrestrial biota

Climate warming and associated environmental changes lead to compositional shifts and local extinctions in various ecosystems. Species closely associated with rare island-like habitats such as groundwater-dependent spring fens can be severely threatened by these changes due to a limited possibility to disperse. It is, however, largely unknown to what extent mesoclimate affects species composition in spring fens, where microclimate is buffered by groundwater supply. We assembled an original landscape-scale dataset on species composition of the most waterlogged parts of isolated temperate spring fens in the Western Carpathian Mountains along with continuously measured water temperature and hydrological, hydrochemical, and climatic conditions. We explored a set of hypotheses about the effects of mesoclimate air and local spring-water temperature on compositional variation of aquatic (macroinvertebrates), semi-terrestrial (plants) and terrestrial (land snails) components of spring-fen biota, categorized as habitat specialists and other species (i.e. matrix-derived). Water temperature did not show a high level of correlation with mesoclimate. For all components, fractions of compositional variation constrained to temperature were statistically significant and higher for habitat specialists than for other species. The importance of air temperature at the expense of water temperature and its fluctuation clearly increased with terrestriality, i.e. from aquatic macroinvertebrates via vegetation (bryophytes and vascular plants) to land snails, with January air temperature being the most important factor for land snails and plant specialists. Some calcareous-fen specialists with a clear distribution centre in temperate Europe showed a strong affinity to climatically cold sites in our study area and may hence be considered as threatened by climate warming. We conclude that prediction models solely based on air temperature may provide biased estimates of future changes in spring fen communities, because their aquatic and semiterrestrial components are largely affected by water temperature that is modified by local hydrological and landscape settings.

13th International Symposium on Aquatic Oligochaeta, Brno, Czech Republic, 7–11 September, 2015

This volume of Biologia journal includes nine papers prepared by authors of presentations at the 13th International Symposium on Aquatic Oligochaeta (ISAO), organized by the Department of Botany and Zoology of the Faculty of Science, Masaryk University, Brno. The symposium was attended by 43 participants from 16 countries, who presented 48 oral and poster contributions. Many of the world’s renowned oligochaete specialists as well as scientists from several countries where research focusing on oligochaete biology is relatively new were present – enabling scientific communication amongst those who are interested in the various fields of fundamental and applied research on this important group of aquatic annelids. The symposium was organized by a small team led by Dr Jana Schenková, Mark Wetzel and Ing Michal Schenk, with invaluable support from many employees and students of the Department of Botany and Zoology. The involvement of other members of the Scientific Committee was invaluable – most of whom were hosts or had assisted in the organization of previous ISAO meetings. This symposium was dedicated to the memory of Dr. Beatrice Sambugar, who passed away in 2014, and also to other deceased members of our global oligochaete family. Beatrice was born in Verona Italy in 1948. She received her undergraduate and doctoral degrees from the University of Padova, Italy. During her professional career, she was employed as a teacher in a Secondary School in Verona, as manager of SARECO, and engineering and consulting firm in Verona, then later as director of Studio SARECO. She was an Associate Researcher at the Museo di Storia Naturale in Verona from 1972 until her death. For many years, Beatrice focused on groundwater fauna and hydrobiology, working closely on many projects with her mentor and professor, Sandro Ruffo – one of the founders of the International Society for Subterranean Biology. During her career, Beatrice prepared numerous reports, and produced pedagogical material and diverse research – primarily related to monitoring and conservation of parks and other protected areas. She was author or coauthor on over 30 publications, focused primarily on the taxonomy, faunistics, distribution and ecology of freshwater oligochaetes, and many specific to subterranean waters in Southern Europe. In collaboration with other colleagues, she described 15 new species in seven genera and four families of oligochaetous Clitellata. Beatrice is survived by her daughter Chiara, a CNRS Researcher at the Institut de Physique Théorique, Paris. Although Chiara expends most of her time doing research on Theoretical Cosmology, she cultivates the love for Nature and Arts that she received from Beatrice. Our family of oligochaetologists, worldwide, will miss the personal warmth, kindness, and professionalism shared by Beatrice, unselfishly, with each of us – yet her spirit, dedication, and enthusiasm lives on in all of us. A more extensive memoriam honoring Beatrice, including citations for her publications, will be published at a later date. The symposium was opened with a welcoming presentation by Dr Jaromír Leichmann, the Dean of the Faculty of Science, Masaryk University. The program consisted of five sessions, which covered a wide range of branches of knowledge dealing with the biology of aquatic oligochaetes: systematics and phylogeny, community ecology, morphology, ecotoxicology and biogeography. Experts from different fields of oligochaetology presented keynote lectures: Dr Christer Erséus: From DNA barcoding and species delimitation to transcriptome phylogenies – on ongoing molecular systematics research on clitellates; Dr Göran Milbrink: Species specific morphological deformities in oligochaetes associated with mercury emissions. Lake Vänern, Southern Sweden, revisited; Dr Pilar Rodriguez: Sperm transfer by spermatophores in microdrile oligochaetes (Annelida, Clitellata); and Dr Tarmo Timm: Fate of Lamprodrilus isoporus Michaelsen, 1901 (Oligochaeta: Lumbriculidae) in eutrophic lakes. A special microscopy session was attended by many symposium participants, with discussions about morphological characters, mounting techniques, and other taxonomic and systematic issues continued late into the night. Similarly, the dedicated poster session initiated broad discussions not only on presented contribution but about all research fields. Social events during this scientific meeting began with an afternoon city walk through Brno with visits to main historical monuments, followed by an evening of comradery at a pleasant pub. The opportunity to become friends continued during a mid-symposium tour, with visits to the medieval Pernštejn Castle and Macocha Abyss and

Environmental impact of heated mining waters on clitellate (Annelida: Clitellata) assemblages

Mining is a relatively highly monitored industry. While chemical pollutants (toxic ions, radionuclides, etc.) have mostly been eliminated from mining waters, other types of environmental pollution (temperature regime alterations, high concentrations of various anions, etc.) can affect benthic invertebrates. In this study, we focused on the effect of mining water effluent on the diversity and density of aquatic Clitellata. Four sampling sites were selected. Three sites in a natural stream (the Nedvědička River, Czech Republic), one upstream and two downstream from the mining effluent, and one site on the mining waters were sampled monthly during 2008–2009. Environmental variables were recorded in and samples were collected from two types of habitats — riffles and pools. The response of clitellate assemblages was evaluated using principal component analysis and generalised estimating equations. The results indicated that the mining effluent caused partial species exchange and had negative effects on clitellate taxa richness and abundance. These responses were specific to both the habitat (riffle/pool) and species sampled. In each of the different taxa studied, we observed one of four typical clitellate responses: (a) elimination of stenotherm species; (b) reduction of clitellate species followed by quick recovery; (c) neutral response; or (d) positive influence. We found that aquatic clitellates, which are considered to be eurytopic with broad ecological valences, are also sensitive to even slight environmental pollution.

Variation of Clitellata (Annelida) assemblages related to water saturation in groundwater-dependent wetlands

Aquatic invertebrates of groundwater-dependent wetlands can be sensitive to a drop in the groundwater table, which is considered one of the possible impacts of climate change. We investigated whether aquatic clitellate species are able to dwell in waterlogged substrates without surface water, in 27 spring fens studied across the Western Carpathians. A total of 78 clitellate species were recorded in pairs of samples from aquatic and semi-aquatic habitats. Semi-aquatic habitats had 27 species in common with aquatic habitats, but algal and fungal feeders were less frequent and abundant, and predatory leeches and Haplotaxis gordioides completely lacking. Terrestrial enchytraeid species enriched the semi-aquatic assemblages. The main change in clitellate composition was controlled by total organic carbon. The importance of further variables, however, differed between aquatic and semi-aquatic sites. Further analyses of semi-aquatic sites showed that the distribution of primarily aquatic species was mainly driven by physical and chemical variables, while that of soil dwellers was driven by depth. Except Tubifex tubifex and Nais communis, all aquatic species preferred the uppermost layer. Results indicate that, during extreme droughts, when aquatic habitats cease to exist, some aquatic clitellates can persist in the waterlogged substrate, while some aquatic specialists may face the risk of local extinction.