Occurrence Of Taxa Research Articles

Seasonal turnover in community composition of stream‐associated macroinvertebrates inferred from freshwater environmental DNA metabarcoding

AbstractMacroinvertebrate communities are crucial for biodiversity monitoring and assessment of ecological status in stream ecosystems. However, traditional monitoring approaches require intensive sampling and rely on invasive morphological identifications that are time‐consuming and dependent on taxonomic expertise. Importantly, sampling is often only carried out once in a year, namely during late winter–spring, where most indicator taxa have larval stages in the streams. Hence, species with divergent phenology might not be detected. Here, we use environmental DNA (eDNA) metabarcoding of filtered water samples collected in both spring and autumn from five streams in Denmark to address seasonal turnover in community composition of stream macroinvertebrates. We find that eDNA read data from the same stream sampling site clearly show different communities in spring and autumn, respectively. For three of the five streams, season even appears to be a more important factor than sampling site for explaining the variation in community composition. Finally, we compare eDNA data with a near‐decadal dataset of taxon occurrences in the same five streams based on kick sampling conducted through a national monitoring program. This comparison reveals an overlap in species composition, but also that the two approaches provide complementary rather than identical insights into community composition. Our study demonstrates that aquatic eDNA metabarcoding is useful for species detection across highly diverse taxa and for identifying seasonal patterns in community composition of freshwater macroinvertebrates. Thus, our results have important implications for both fundamental research in aquatic ecology and for applied biomonitoring.

First insights into the wood management for the production of lime given by the anthracological study of a 19th century lime kiln from Martinique, Lesser Antilles

The colonial economy of Martinique, French West Indies, has long been based on sugar cane exploitation, which started in the 17th century and decreased during the 19th century. Sugar economy led to woodland exploitation for the production of fuel. In particular, this fuelwood was needed for lime production, which was used for the purification of cane juice. As lime kilns are numerous in Martinique, their functioning implied an intense wood exploitation. To date, no archaeobotanical studies were conducted to assess how lime kiln workers used and managed wood for the production of fuel. In this study, we analyzed 207 wood charcoals fragments from a 19th century lime kiln at the Sucrerie plantation, Les Anses-d’Arlet, Martinique. This led to the identification of 50 taxa, showing that wood collection was mainly diffuse and unfocused. But the occurrence of taxa known as being used for fuelwood or charcoal production suggests that lime kiln workers were looking for wood with good fuel properties. Our results also show that the collection of wood was made locally, as revealed by the presence of a xero- to mesophilic vegetation in the anthracological record, which is in accordance with botanical and ethnological data. The presence of pioneer and heliophilic taxa also suggest that the vegetation was already impacted by wood exploitation, i.e., local forest associations were largely disturbed by this time and secondary regrowth was conspicuous. Nevertheless, the high proportion of small-gauge wood charcoals fragments (36%) and the presence of edible taxa in the anthracological record suggest that saplings and pruning waste may have been preferred to preserve useful and mature trees. This study allows for the first time to assess which fuelwood was used by Antillean lime kiln workers during the colonial Period which makes it possible to better understand one of the most widespread handicrafts during the sugar exploitation in the Caribbean.

A New Method for Integrating Ecological Niche Modeling with Phylogenetics to Estimate Ancestral Distributions.

Ancestral range estimation and projection of niche models into the past have both become common in evolutionary studies where the ancient distributions of organisms are in question. However, these methods are hampered by complementary hurdles: discrete characterization of areas in ancestral range estimation can be overly coarse, especially at shallow timescales, and niche model projection neglects evolution. Phylogenetic niche modeling accounts for both of these issues by incorporating knowledge of evolutionary relationships into a characterization of environmental tolerances. We present a new method for phylogenetic niche modeling, implemented in R. Given past and present climate data, taxon occurrence data, and a time-calibrated phylogeny, our method constructs niche models for each extant taxon, uses ancestral character estimation to reconstruct ancestral niche models, and projects these models into paleoclimate data to provide a historical estimate of the geographic range of a lineage. Models either at nodes or along branches of the phylogeny can be estimated. We demonstrate our method on a small group of dendrobatid frogs and show that it can make inferences given species with restricted ranges and little occurrence data. We also use simulations to show that our method can reliably reconstruct the niche of a known ancestor in both geographic and environmental space. Our method brings together fields as disparate as ecological niche modeling, phylogenetics, and ancestral range estimation in a user-friendly package. [Ancestral range estimation; ancestral state reconstruction; biogeography; Dendrobatidae; ecological niche modeling; paleoclimate; phylogeography; species distribution modeling.].

INCORPORATING INFORMATION ON VARYING SEDIMENTATION RATES INTO PALEONTOLOGICAL ANALYSES

ABSTRACTStratigraphic changes in the clustering of first or last taxon occurrences are a joint expression of evolutionary, ecological, taphonomic, and sedimentological processes. Sedimentation rates control the degree of sedimentary dilution and condensation and thus alter the time contained in a given thickness of sediment. However, it remains poorly explored quantitatively how distinct the stratigraphic patterns in the first and last occurrences can be under different deposition models with a constant thickness of accumulated sediment. Here, I present an algorithm that translates ecological or evolutionary signals between time and stratigraphic height. It is implemented for R Software as the package DAIME and complemented by tools to quantify the uncertainties associated with the construction of deposition models. By modeling the stratigraphic expression of the K/Pg extinction and an earlier extinction pulse potentially linked to Deccan volcanism on Seymour Island under varying sedimentation rates, I show that (1) clustering of last occurrences ∼ 250 kyr prior to the K/Pg boundary can be equally explained by a stronger earlier extinction pulse or prolonged intervals with reduced sediment accumulation rate, but (2) when the temporal variability in sedimentation rate is known, the most plausible extinction dynamics can still be identified. The approach is applicable for any type of information transported as a part of the sedimentary record (e.g., fossils or trace elements) or data derived from it (e.g., isotope ratios and rates of morphological evolution).

Palynostratigraphy of the lower Paleogene Margaret Formation at Stenkul Fiord, Ellesmere Island, Nunavut, Canada

The upper Paleocene to lower Eocene Margaret Formation exposed at Stenkul Fiord on southern Ellesmere Island, Nunavut, Canada, represents a nearly continuous terrestrial succession of microfossil-rich clastic sediments and coal. These strata were deposited at a time of extensive tectonic activity associated with Eurekan deformation. The precise chronology of the Eurekan deformation is poorly known. Prior studies at Stenkul Fiord provided a stratigraphic overview and relative age estimates for exposed strata but lack the absolute age control required to investigate the timing of deformation events. Strata at Stenkul Fiord preserve evidence of Arctic forests that may have grown during hyperthermal events that characterized the Paleogene, namely, the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2). A quantitative palynological approach is herein used to define a new higher-resolution biostratigraphic framework for the Margaret Formation strata at Stenkul Fiord. This resulting improved biostratigraphic framework is integrated with new absolute age control of 53.7 ± 0.06 Ma provided by U-Pb ID-TIMS of zircon preserved in an ash bed within the studied succession. Nine pollen zones are defined based on cluster analysis, NMDS ordination, first- and last occurrences of taxa, and angiosperm pollen taxa diversity (H′). The presence of thermophilic pollen taxa at Stenkul Fiord provides evidence of climates related to the globally warm climates during the early Paleogene.

<strong>Annotated List of Orchidaceae for Myanmar</strong>

A list of all Orchidaceae recorded for Myanmar is presented, primarily based on many years of research in herbaria and libraries around the world, supplemented by recent fieldwork in various parts of Myanmar. As such, it is intended to form the basis for a treatment of Orchidaceae in the new flora of Myanmar project. A total of 1037 species in 152 genera is listed, which includes a number of uncertain identifications and indicates the need for further research. In addition, for four taxa occurrence in Myanmar is also suspected, but the available herbarium and literature information is not conclusive in this regard. The total number is comparatively low relative to neighbouring Thailand but expected to rise, given the fact that biodiversity is currently poorly understood even though extensive inventory efforts are now under way. In the introduction, the orchid flora of Myanmar, phytogeographical affinities and endemism are discussed and illustrated by graphs and tables. Each species entry in the taxonomic section consists of the name, place of original description, type information (if from Myanmar), list of citations of Myanmar specimens examined and global distribution; specific notes under many species elaborate various taxonomic issues. Two new combinations are made here, and five lectotypes and one neotype are designated. Six species are definite new distribution records for Myanmar, whereas identification of another three needs to be confirmed.

Autecology of terrestrial diatoms under anthropic disturbance and across climate zones

Like aquatic diatoms, terrestrial diatoms are sensitive to multiple environmental factors such as pH, anthropic disturbances, soil moisture and nitrogen. While most aquatic diatom species have well-known autecological values for several important variables, qualifying them as biological indicators, this potential has not yet been untapped for terrestrial diatoms. Here, we aim to establish autecological values for pH and soil moisture content using weighted averaging for common, widespread terrestrial diatoms and compare them with previous calculated indicator values and tolerance ranges. In order to provide robust autecological values, we combined the data of ecological studies carried out across a range of climate conditions. We found that our validation metrics improved considerably after removing samples collected in anthropic disturbed habitats, suggesting that anthropic disturbance is the principal factor defining taxon occurrences. Besides our results showing similarities with previous studies, they also showed a significant improvement on the existing indicator values. Moreover, we expanded the list of terrestrial diatoms to 249 taxa that may serve as environmental markers in different research fields.

Wide diversity of parasites in Bombus terrestris (Linnaeus, 1758) revealed by a high-throughput sequencing approach.

Assessing the extent of parasite diversity requires the application of appropriate molecular tools, especially given the growing evidence of multiple parasite co-occurrence. Here, we compared the performance of a next-generation sequencing technology (Ion PGM ™ System) in 12 Bombus terrestris specimens that were PCR-identified as positive for trypanosomatids (Leishmaniinae) in a previous study. These bumblebees were also screened for the occurrence of Nosematidae and Neogregarinorida parasites using both classical protocols (either specific PCR amplification or amplification with broad-range primers plus Sanger sequencing) and Ion PGM sequencing. The latter revealed higher parasite diversity within individuals, especially among Leishmaniinae (which were present as a combination of Lotmaria passim, Crithidia mellificae and Crithidia bombi), and the occurrence of taxa never reported in these hosts: Crithidia acanthocephali and a novel neogregarinorida species. Furthermore, the complementary results produced by the different sets of primers highlighted the convenience of using multiple markers to minimize the chance of some target organisms going unnoticed. Altogether, the deep sequencing methodology offered a more comprehensive way to investigate parasite diversity than the usual identification methods and provided new insights whose importance for bumblebee health should be further analysed.

The Taxon Hypothesis Paradigm-On the Unambiguous Detection and Communication of Taxa.

Here, we describe the taxon hypothesis (TH) paradigm, which covers the construction, identification, and communication of taxa as datasets. Defining taxa as datasets of individuals and their traits will make taxon identification and most importantly communication of taxa precise and reproducible. This will allow datasets with standardized and atomized traits to be used digitally in identification pipelines and communicated through persistent identifiers. Such datasets are particularly useful in the context of formally undescribed or even physically undiscovered species if data such as sequences from samples of environmental DNA (eDNA) are available. Implementing the TH paradigm will to some extent remove the impediment to hastily discover and formally describe all extant species in that the TH paradigm allows discovery and communication of new species and other taxa also in the absence of formal descriptions. The TH datasets can be connected to a taxonomic backbone providing access to the vast information associated with the tree of life. In parallel to the description of the TH paradigm, we demonstrate how it is implemented in the UNITE digital taxon communication system. UNITE TH datasets include rich data on individuals and their rDNA ITS sequences. These datasets are equipped with digital object identifiers (DOI) that serve to fix their identity in our communication. All datasets are also connected to a GBIF taxonomic backbone. Researchers processing their eDNA samples using UNITE datasets will, thus, be able to publish their findings as taxon occurrences in the GBIF data portal. UNITE species hypothesis (species level THs) datasets are increasingly utilized in taxon identification pipelines and even formally undescribed species can be identified and communicated by using UNITE. The TH paradigm seeks to achieve unambiguous, unique, and traceable communication of taxa and their properties at any level of the tree of life. It offers a rapid way to discover and communicate undescribed species in identification pipelines and data portals before they are lost to the sixth mass extinction.

Standard trees versus underwood: Historical patterns of tree taxon occurrence in coppice forests

AbstractQuestionsCoppice woods were once widespread in Europe. It is usually assumed that underwood tree taxon composition was not directly influenced by people, whereas especially Quercus was promoted among standard trees. However, no work has quantitatively tested these assumptions. Our main question was whether there were any patterns in our data to suggest that certain trees occurred more frequently as standards than as underwood, possibly as a result of management decisions.LocationCzech Republic.MethodsWe constructed a database covering 12,000 hectares of forests around AD 1900. We recorded the occurrence of tree taxa for standards and underwood in 1,507 compartments in 21 forest units. We visualised patterns in these data by bar graphs and chord diagrams. We analysed correlation patterns through association analysis and co‐correspondence analysis.ResultsThere was a statistically significant association between the occurrences of standards and underwood in individual compartments for Quercus, Alnus, Carpinus, Fagus, Larix, Populus tremula and Tilia. Only Quercus standards and underwood showed a positive association. The taxon composition of standards and underwood in forest compartments was statistically significantly correlated.ConclusionsNo simple answer can be given to the question whether or not the taxon composition of standards and underwood in coppice woods differed as a result of management. At the level of individual tree taxa, some trees were more common as standards while others, as underwood. However, the prevalence of Quercus among standards was not confirmed because in our study area Quercus was a common underwood tree as well. At the same time, no significant differences were apparent in the taxon composition of standards and underwood in individual forest compartments. It seems difficult to differentiate between the effects of human selection and indirect selection through natural properties and environmental factors. Our results also highlight the need to carefully consider the properties of written historical sources.

A Hirnantian holdover from the Late Ordovician mass extinction: phylogeny and biogeography of a new anthracocrinid crinoid from Estonia

AbstractRelatively few Hirnantian (Late Ordovician) crinoids are known, and none has been previously described from the palaeocontinent of Baltica. This has impaired our ability to understand the patterns of extinction and biogeographic dispersal surrounding the Late Ordovician mass extinction, which triggered a major turnover in crinoid faunas. Here, we describe Tallinnicrinus toomae gen. et sp. nov., an anthracocrinid diplobathrid from the Hirnantian of northern Estonia. Tallinnicrinus is the youngest member of the Anthracocrinidae and the first representative of the family to occur in Baltica. Morphologically, Tallinnicrinus is unusual in that the radial and basal plates are in a single circlet of 10 plates, similar to the anthracocrinid Rheocrinus Haugh, 1979 from the Katian of Laurentia. Phylogenetic analysis further confirms a close relationship between Tallinnicrinus and Laurentian anthracocrinids, suggesting biogeographic dispersal of the lineage from Laurentia to Baltica during the late Katian or early Hirnantian. The occurrence of this new taxon establishes that the family Anthracocrinidae survived the first pulse of the Late Ordovician mass extinction. However, the lineage remained a ‘dead clade walking’ because it failed to diversify in the wake of the end‐Katian extinction and ultimately went extinct itself by the end of the Ordovician.

Linking Agrobiodiversity Data through Metadata Standards

Agrobiodiversity, or biodiversity for food and agriculture, plays a major role in the sustainability of food production. As stated by FAO 2019, agrobiodiversity can provide food production systems and society with a variety of services as ecosystem services, crops resilience to threats, sustainable intensification, livelihoods, food security and nutrition. The official definition of the concept has been given by CBD 2000 as "a broad term that includes all components of biological diversity of relevance to food and agriculture, and all components of biological diversity that constitute the agroecosystem: the variety and variability of animals, plants and micro-organisms, at the genetic, species and ecosystem levels, which are necessary to sustain key functions of the agro-ecosystem, its structure and processes". Thus, agrobiodiversity is primarily based on species and their function in agroecosystems. Many projects for sharing agrobiodiversity data in a structured way have emerged over the years. One realizes in looking at the Bioversity International (2018) crop descriptors list that the earliest groups of descriptors for crops and some associated data emerged back in the 1970s. In the same list, there are four multi-crop descriptors and derived standards, which are broad standards for crop-related data, namely: Core descriptors for in situ conservation of crop wild relatives v.1 (Thormann et al. 2013); FAO/Bioversity multi-crop passport descriptors V.2.1 (Alercia et al. 2015); Descriptors for farmers' knowledge of plants (Aknazarov et al. 2009); Descriptors for Genetic Marker Technologies (Vicente et al. 2004). Core descriptors for in situ conservation of crop wild relatives v.1 (Thormann et al. 2013); FAO/Bioversity multi-crop passport descriptors V.2.1 (Alercia et al. 2015); Descriptors for farmers' knowledge of plants (Aknazarov et al. 2009); Descriptors for Genetic Marker Technologies (Vicente et al. 2004). These standards share some core elements in common, as taxon, location, a period of collecting, and were intended to be used in the context of data on the occurrence of species in nature. Darwin Core, a TDWG standard commonly used for sharing data of taxon occurrence in nature (Wieczorek et al. 2012), is a globally used metadata standard, representing "a large majority of the 1.4 billion of species occurrence records shared by the Global Biodiversity Information Facility (GBIF), published by more than 1561 organizations in 59 countries in January 2020" (Body et al. 2020). Darwin Core is a standardized language that applies unique Internationalized Resource Identifiers (IRIs) to each element assigned as a metadata element, plus a label and a definition. It improves the interoperability between databases in the context of the Semantic Web (Duerst and Suignard 2005). We believe it is possible to use Darwin Core to represent agrobiodiversity data if a metadata extension is developed to enroll the agrobiodiversity concepts missing in Darwin Core. Thus, a research project held at the University of São Paulo in partnership with Brazilian Agricultural Research Corporation started to map concepts and descriptors from the literature for agrobiodiversity data representation. This project is the sequence of the research initiated by Soares et al. 2019. The crop descriptors published by Bioversity International (2018) may be integrated into the metadata extension, but also other standards like Global Genome Biodiversity Network (GGBN) Data Standard v1 (Droege et al. 2016) and the Darwin Core germplasm extension (DwC-germplasm). At the moment, we are designing a mind map to organize the agrobiodiversity concepts. We expect the metadata extension will be useful for the scientific community to share agrobiodiversity data as linked data, applying Resource Description Framework (RDF) as a resource relationship model, for example.

Njoerdichthys dyckerhoffi gen. et sp. nov. (Pycnodontiformes, lower Turonian) northward migration caused by the Cretaceous Thermal Maximum

A new pycnodont taxon, Njoerdichthys dyckerhoffi gen. et sp. nov., from the Turonian of the Lower Saxony Basin of Germany is described and its systematic positions is established based on phylogenetic analyses of three specimens using slightly altered data matrices. All analyses display some differences to previous analyses but show very similar results to each other apart from the interpretation of the position of several taxa such as, e.g., Palaeobalistum. The new pycnodontiform specimens from northwestern Germany are unambiguously identified as a derived member of Pycnodontidae with close relationships to Abdobalistum and Nursallia? goedeli because of the unique combination of characters. One of the three specimens represents a juvenile form. Its morphological characters are limited, but it shares some characters with Njoerdichthys dyckerhoffi gen. et sp. nov. and is consequently allocated to the new taxon. The systematic placement of the new taxon, Njoerdichthys gen. nov., within Pycnodontidae is surprising since it does not display the one autapomorphic character (postparietal brush-like extension for muscle attachment) previously proposed to define this clade, but rather displays a combination of derived and homoplastic characters indicating that the definition of supra-generic taxa needs to be re-evaluated in the future by including more and new taxa. The distribution of pycnodontiform fishes in the Cretaceous appears to concur with changes in global climatic conditions, where high upper-ocean temperatures and high sea levels allow these fishes to migrate into higher latitudes as evidenced by the occurrence of the new taxon and Anomoeodus subclavatus in the Campanian of Sweden.

A preliminary survey of the abundance, diversity and distribution of terrestrial macroinvertebrates of Gcwihaba cave, northwest Botswana

Inventories of cave species and in-depth understanding of cave ecosystems are essential for informing conservation approaches for the unique and vulnerable cave fauna. Gcwihaba cave is the largest cave in Botswana but its ecology is poorly understood. This study set out to provide the first quantitative survey of the cave’s terrestrial macroinvertebrates. Macroinvertebrates were collected from sample sites at 10 m intervals into the cave from the cave entrance. At each site, macroinvertebrates on the cave floor were collected by quadrat sampling while macroinvertebrate from cave walls were collected by visual opportunistic searches. Moisture content, pH and electrical conductivity of the cave floor substrate were measured at each site to examine the influence of the floor properties on the distribution of macroinvertebrates on the cave floor. Twelve species in 10 families and 8 orders of terrestrial macroinvertebrates were collected. The occurrence of taxa varied across the sites, with most taxa occurring in the light and twilight sectors of the cave (within 30 m), whereas the dark sector (beyond 30 m) was dominated by cave cockroaches (Gyna sp.). The abundance of the cave cockroaches, darkling beetles (Tenebrionidae, Tenebrio sp.) and cave wasps (Sphecidae) positively correlated with floor substrate of high moisture content and high electrical conductivity, which became increasingly common with distance into the cave. The abundance of other taxa from the cave floor positively correlated with a floor substrate of high pH and low moisture, which was common near the cave entrance.

Spatial variability of aquatic macroinvertebrate assemblages in the Okavango Delta, Botswana: considerations for developing a rapid bioassessment tool

Spatial variability in macroinvertebrate assemblages of the Okavango Delta, Botswana, was examined to evaluate differences in assemblages at a regional and habitat scale. Sampling was undertaken six times during a one-year cycle from 2005 to 2006, with 228 macroinvertebrates samples collected from different aquatic habitats in 22 sites in four study areas. Sixty-four taxa, mainly families, and >30 000 individuals were recorded. Multivariate analysis of aquatic macroinvertebrates revealed that the distribution of macroinvertebrate fauna is relatively homogenous among study regions, with some variation in number of taxa. Differences were observed in the macroinvertebrate assemblages associated with different aquatic habitats, with fauna from deltaic habitats (floating vegetation, inundated floodplain and marginal vegetation) different from non-deltaic habitats (isolated, seasonally flooded pools and isolated, temporary, rain-filled pools). Within the deltaic habitats, there were no significant differences among the habitats in terms of number of taxa and abundance, although assemblages and frequency of occurrence of taxa differed among habitats, providing evidence of habitat preferences for certain taxa. Future development of a macroinvertebrate-based bioassessment tool should account for aquatic habitat, although the tool does not need to be region specific. Temporal variability of macroinvertebrate assemblages should be examined to evaluate potential hydrological effects on the tool.

An updated checklist of the vascular flora of Montagna di Torricchio State Nature Reserve (Marche, Italy)

This study aims to increase floristic knowledge of Marche by means of a survey in the Montagna di Torricchio State Nature Reserve (central Italy). The Reserve, located in the central Apennines, covers about 3.2 km2 at altitudes ranging from 820 to 1,491 m a.s.l. It has been owned and managed as a strict reserve by the University of Camerino since 1970: all the anthropic activities ceased about 50 years ago, except for a minimal area where mowing and cattle grazing are still allowed. The floristic list consists of 789 specific and subspecific taxa belonging to 81 families and 352 genera. Two species are new for Italy (Taraxacum calocarpum and T. pulchrifolium) and 14 for Marche regional flora. Compared to previous floristic studies, we found 127 more taxa but we showed a certain stability in the life-form spectrum, suggesting limited effects of dynamic processes related to climate and land-use changes. The negligible number of alien species (11) is probably related to the limitations to anthropic activities in the Reserve. The occurrence of taxa never recorded for Italy and Marche highlights the floristic value of the Reserve for species conservation in the central Apennines.

On certain Peruvian type localities of birds (Aves) in Mlíkovský (2009).

According to the ICZN (1999), the type locality is where the specimen used as holotype, syntype or lectotype was collected (Art. 76). As such, the type locality is a source of information about the habitat and geographical occurrence of a taxon. Topotypes, specimens collected within the type locality of a species or subspecies, have been used in comparison with other specimens to corroborate the identity of the latter (e.g. Tautz et al. 2003; Vuataz et al. 2011). Other studies have used type localities in reporting apparent extinctions (e.g. Williams 2015), or degradation of the taxon's habitat (e.g. Wirth 2018). Thus, type localities have information value for scientific collections, and may be of special conservation concern.

Diversity of Diatoms in Phytobenthos Communities of the Shchugor River in the Urals (The Komi Republic, Russia)

AbstractThe composition of diatom assemblages of epilithon, epiphython and epipelon in the Shchugor River was presented. Biofoulings of rocky substrates, macrophytes, filamentous algae and samples from the surface of bottom sediments were studied. The diatom assemblages had a diverse composition and included 218 species with varieties and forms from 60 genera, 27 families and 12 orders. The order Naviculales (56 taxa) and the family Fragilariaceae (39 taxa) played a major role. The genera Gomphonema (17 taxa), Nitzschia (16), Navicula (14), Eunotia (14) were dominant by the species abundance. The identified diatoms were mostly epiphytes, indifferent to salinity and alkaliphilous species, clean water indicators. The most common community in the river was epilithon, whereas epiphyton distinguished by the most diverse composition. The epipelon was poorly developed, having the lowest number of diatom taxa.Dominant, subdominant, accompanying species of the diatoms were very similar in different phytobenthos groups, the Sørensen-Czekanowski coefficients varied from 0.70 to 0.81. The dominant species were Achnanthidium minutissimum, Encyonema minutum, Fragilaria gracilis, Gomphonema exilissimum, G. ventricosum, Hannaea arcus, Meridion circulare. The sub-dominant species were Cocconeis placentula, Nitzschia fonticola, Ulnaria ulna and Staurosirella pinnata. Based on the Berger-Parker and Simpson variety indices, the occurrence of taxa in the genera and families in the epiphyton was more uniform. The assessment of benthic diatoms demonstrated that the Shchugor River is a typical mid-mountain river. Diatom communities of epilithon, epiphython and epipelon can be used for the monitoring of ecological status of the river.

Microcostatus elisabethianus, a new limnoterrestrial diatom species (Bacillariophyta) from the sub-Antarctic region

Background and aims – During a survey of the soil diatom flora of the sub-Antarctic islands in the southern Indian Ocean, an unknown small-celled naviculoid taxon was discovered living in small cracks in cliffs bordering the ocean. The taxon showed a set of morphological features only found in the genus Microcostatus. However, the unknown taxon could not be identified using the currently available literature. Methods – Using both light microscopical and scanning electron microscopical techniques, the morphology of the unknown Microcostatus taxon was documented. The new taxon is described, illustrated and compared with all other similar Microcostatus taxa worldwide. Key results – Microcostatus elisabethianus possesses a unique combination of morphological features that excludes conspecificity with all other members of the genus. It is characterized by a lanceolate valve outline with protracted, elongate apices, a very large, porous conopeum reaching the valve margins and uniseriate striae composed of only one macroareola and mantle areolae restricted to the valve apices. The morphological features of the genus Microcostatus are evaluated and discussed. Notes on the occurrence and ecology of the new taxon are added.

Negative Impact of Invasive Plants on Riverbank Vegetation

The research presented in this paper deals with the issue of invasive plant species. Invasive plants are characterized with the high regeneration potential and with a negative effect on populations of our native species and habitats. The occurrence of these plant taxon at a given site is not natural, and their appearance outside of their natural habitat is most often due to anthropogenic activity. Our research is focused on plant species Fallopia japonica and Impatiens glandulifera. The aim of the study is the determination of suppressing possibilities of their negative impact on riverbank vegetation. From the results of the first stage of the research, it is known that plant material is transported downstream, the ability of reproduction of the plant material maintain for at least for 4 weeks, and after being caught on the riverbank, it can establish a new population. The overgrowth of these invasive species presents a risk to the original riverbank vegetation, and the ecological stability is being disturbed. The eradication and prevention system is a necessary solution to this problem. The research is conducted on the Blatina River in Pezinok, Slovakia. The first method of eradication was the mechanical removal of Fallopia japonica. The two selected localities were cut. In the next growing season, an increase in the population of Fallopia japonica was recorded, and one new location was created. The second method of eradication was the chemical method. For chemical eradication, spraying based on the Invasive Plant Removal Guidelines for the Slovak Republic was used. An important finding was that the effectiveness of the chemical eradication is dependent on the area of the sprayed leaves and independent on the concentration of the solution. The next step was the comparison of vegetation cover after mechanical and chemical eradication. A soil probe was performed on two selected areas; area after the mechanical eradication and the area after chemical eradication. A root sample was taken from both areas. Subsequently, the viability of the root system and its stabilizing function with respect to bank erosion were evaluated. The effectiveness of chemical eradication was much stronger. The most optimal way is to remove the plant at their early stage of the growing cycle when the leaf area is smaller. The result is then ecologically and economically more advantageous. After chemical eradication, it is necessary to remove dead plant residues in the autumn to create optimal light and wet conditions for the growth of potential natural vegetation. Invasive plants in riverbank vegetation have a negative impact on stability and potential natural vegetation. The best way to control their incidence is eradication.