Species richness of tree and shrub layers in riparian forests of the Western Caucasus dominated by alien species

The consequences of replacement of native dominants by alien species (Ailanthus altissima, Ficus carica, Robinia pseudoacacia, Acer negundo, and Amorpha fruticosa) in the tree and shrub layers have been studied in riparian forests of the Western Caucasus. The results show that the invasive dominant species do not always achieve higher abundance, compared with native dominants. When this is the case, however, the dominance of alien species as stronger competitors leads to reduction in the species richness of communities, because they not only intercept the greater part of resources from the environment but also provoke increasingly strict partitioning of remaining resources among associated species.     

Occurrence of DNA methylation in Daphnia magna and influence of multigeneration Cd exposure

Most of the research on the epigenetic phenomenon of DNA methylation has been performed with vertebrates and plants. Knowledge on DNA methylation in Daphnia magna, a key test organism in aquatic toxicology, is completely lacking. Through epigenetic inheritance, effects of transient chemical exposure could be transferred to non-exposed generations, which could have a major impact on ecological risk assessment procedures. In this study, we determined if CpG methylation occurs in D. magna and if this can be influenced by exposure to toxic substances. Homologs of human DNA methyltransferases DNMT1, DNMT2 and DNMT3A were found in the partially available D. magna genome. Using an optimized “Amplification of Intermethylated Sites (AIMS)” technique, two methylated fragments were discovered in D. magna DNA. No homology was found for these sequences. The methylation and the D. magna origin of the fragments were confirmed with Southern analysis. This optimized AIMS technique was then applied to DNA of D. magna which were exposed to 180 µg/L Cd for two generations. Exposure resulted in a significant decrease in reproduction. The same methylated fragments with the same band intensity were observed in DNA of both non-exposed and exposed daphnids. As such, it could not be demonstrated that Cd exposure altered DNA methylation. However, the presence of DNA methylation in D. magna shows that potentially epigenetic effects may occur in this species.     

The role of interactions between individual animals in the response to heat stress in the freshwater crustacean <Emphasis Type="Italic">Daphnia magna</Emphasis>

The thermal resistance of Daphnia magna Straus is a trait depending on the interaction between individuals. The group effect is expressed in D. magna as both a decrease in thermal resistance and a marked individual differentiation with respect to thermal resistance. Two types of interactions between individual D. magna have been found: (1) the release of an unidentified factor decreasing thermal resistance (without noticeably changing the phenotypic variability of this trait) into the medium and (2) a decrease in the thermal resistance of individuals poorly adapted to heat stress, with the thermal resistance of well-adapted individuals (determined by the dependence of thermal resistance on interactions between individuals) remaining the same or even slightly increasing.Translated from Ekologiya, No. 2, 2005, pp. 126–131.Original Russian Text Copyright © 2005 by Kalinnikova, Krasnoperova, T. Gainutdinov, Sadykova, M. Gainutdinov.     

Comparative toxicity of solid waste leachates to Daphnia magna

The comparative acute and chronic toxicities of municipal, industrial, coal-fired power plant, and synthetic fuel solid waste leachates to the aquatic invertebrate Daphnia magna were determined. Seventeen leachates were laboratory-derived by extraction with 0.5 N acetic acid, and one, an arsenic-contaminated groundwater, was naturally derived. The acute toxicity 48-h LC₅₀ estimates (concentrations of the test materials that killed 50% of the test organisms in 48 h) ranged from 0.0005% for a dye waste leachate to > 100% (i.e., undiluted) for a coal gasification waste leachate. The most toxic leachates were derived from a dye waste, a plater's waste, and the arsenic-contaminated groundwater, and the least toxic were from a soybean process cake waste and a coal gasification waste. Of the 16 leachates used in the 28 day chronic toxicity tests, only the arsenic-contaminated groundwater and a municipal sewage sludge significantly affected D. magna reproduction. The former material at 1.0% concentration and the sludge at 0.1% caused about an 88% reduction in the numbers of young produced by exposed females compared with controls. Generally, the industrial waste leachates were more toxic than those from the power plant and synthetic fuel wastes. Because its presence in the test materials interfered with interpretation of the results, acetic acid may not be an appropriate extraction medium for preparation of leachates.     

Inhibition of restorative succession by invasive plant species: Examples from southeastern Belarus

Consideration is given to the examples of suppression of restorative succession by invasive plant species (Solidago canadensis L., Helianthus subcanescens (A. Gray) E. Watson, Impatiens glandulifera Royle) in anthropogenic landscapes of southeastern Belarus. Characteristics of communities blocking the succession process have been revealed: low species richness, dominance of alien species in coverage, high level of synanthropization, and the absence of natural regeneration of trees and shrubs. It is suggested that a delay in succession is caused by the suppressing influence of transformer species on seed germination in apophytic trees.     

Expansion of invasive alien plant species in the republic of Bashkortostan, the Southern Urals: Analysis of causes and ecological consequences

The causes and ecological consequences of alien plant species invasions in the Southern Urals are analyzed. Aggressive invasive species of North American origin??Ambrosia trifida L., A. psylostachya DC., Cyclachaena xanthiifolia (Nutt.) Fresen., Hordeum jubatum L., Oenothera biennis L., Bidens frondosa L., etc.??have invaded synanthropic and natural plant communities and became dominant, with their proportion varying from 10 to 99%. The biomass of these plants may reach 6 kg/m²; density, more than 1000 shoots per square meter; and seed production, up to 30000 seeds per plant, which explains their dominance in communities. The ecological hazard they pose lies in the displacement of native species, overgrowing of disturbed land areas, and allergenicity of their pollen.     

Comparative Sensitivity to the Insecticides Deltamethrin and Esfenvalerate of Some Aquatic Insect Larvae (Ephemeroptera and Odonata) and Daphnia magna

Sensitivity to the pyrethroids deltamethrin and esfenvalerate (aqueous solution) and LC₅₀ have been determined in acute (96-h) toxicological tests on mayfly larvae (Cloeon dipterum and Caenis miliaria), damselfly larvae (Lestes sponsa and Cordulia aenea), and juveniles from a laboratory culture of Daphnia magna. Sensitivity to deltamethrin increases in the series C. aenea (Odonata) < D. magna (Cladocera) < L. sponsa (Odonata) < C. miliaria(Ephemeroptera) < C. dipterum (Ephemeroptera), and that to esfenvalerate, in the series C. aenea < D. magna < L. sponsa C. miliaria C. dipterum. The values of LC₅₀ about 0.01 g/l determined for mayfly larvae are below those known for various hydrobionts from the literature, indicating a very high sensitivity of these insects to pyrethroids.     

Comparison of morphological defences in asexually and sexually reproduced eggs of Daphnia (D. galeata and D. similis) against fish kairomones

In the present study, we investigated morphological changes of hatchlings from asexually and sexually produced eggs of Daphnia galeata and D. similis against fish kairomones. In both species, hatchlings from asexual eggs showed induced traits, such as short body length, long tail spine and high relative tail spine length when influenced by fish kairomones. However, hatchlings from sexual eggs expressed high relative tail spine length regardless of kairomones presence. The results showed that the inducibility of morphological defences depends on the egg type, with inducible defences predominant in asexual eggs while fixed defences are employed by the offspring of sexual eggs in Daphnia.     

Interspecific interactions of amphipods <Emphasis Type="Italic">Gammarus lacustris</Emphasis> and <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis>

Experimental studies of interactions between two amphipod species (Gmelinoides fasciatus and Gammarus lacustris) showed that predation is the basic mechanism accounting for their mutual exclusion in nature. Mortality from predation among similar-sized specimens of both species at an equal abundance ratio was similar (24–25% in G. lacustris and 27–30% in G. fasciatus). The displacement of G. lacustris by G. fasciatus was observed when the latter was dominant. Adult G. fasciatus and G. lacustris successfully preyed on juveniles of their competitors and did not differ significantly in daily food consumption as a percentage of body weight: 6–24% at a fresh body weight of 18–24 mg in both species. The potential for rapid population growth under new conditions contributed to the success of the invasive Baikal species G. fasciatus in displacing G. lacustris from many water bodies of Russia.     

Priority and emerging flame retardants in rivers: Occurrence in water and sediment,Daphnia magna toxicity and risk assessment

The occurrence, partitioning and risk of eight polybrominated diphenyl ethers (PBDEs), nine new brominated (NBFRs) and ten organophosphorus flame retardants (OPFRs) were evaluated in three Spanish rivers suffering different anthropogenic pressures (Nalón, Arga and Besòs). OPFRs were ubiquitous contaminants in water (ΣOPFRs ranging from 0.0076 to 7.2 μg L^− 1) and sediments (ΣOPFRs ranging 3.8 to 824 μg kg^− 1). Brominated flame retardants were not detected in waters, whereas ΣPBDEs ranged from 88 to 812 μg kg^− 1 and decabromodiphenyl ethane (DBDPE) reached 435 μg kg^− 1 in sediments from the River Besòs, the most impacted river. The occurrence of flame retardants in river water and sediment was clearly associated with human activities, since the highest levels occurred near urban and industrial zones and after wastewater treatment plants discharge. Daphnia magna toxicity was carried out for OPFRs, the most ubiquitous flame retardants, considering individual compounds and mixtures. Toxicity of nine tested OPFRs differed largely among compounds, with EC₅₀ values ranging over three magnitude orders (0.31–381 mg L^− 1). Results evidenced that these compounds act by non-polar narcosis, since their toxicity was proportional to their lipophilicity (K_ow). Furthermore, their joint toxicity was additive, which means that single and joint toxicity can be predicted knowing their concentration levels in water using quantitative structure activity relationships (QSARs) and predictive mixture models. Based on these results, a risk assessment considering joint effect was performed calculating and summing risk quotients (RQs) for the water and sediment samples. No significant risk to D. magna (ΣRQs < 1) was observed for any of the monitored rivers.     

An interlaboratory comparison of nanosilver characterisation and hazard identification: Harmonising techniques for high quality data

Within the FP7 EU project NanoValid a consortium of six partners jointly investigated the hazard of silver nanoparticles (AgNPs) paying special attention to methodical aspects that are important for providing high-quality ecotoxicity data. Laboratories were supplied with the same original stock dispersion of AgNPs. All partners applied a harmonised procedure for storage and preparation of toxicity test suspensions. Altogether ten different toxicity assays with a range of environmentally relevant test species from different trophic levels were conducted in parallel to AgNP characterisation in the respective test media. The paper presents a comprehensive dataset of toxicity values and AgNP characteristics like hydrodynamic sizes of AgNP agglomerates and the share (%) of Ag⁺-species (the concentration of Ag⁺-species in relation to the total measured concentration of Ag). The studied AgNP preparation (20.4 ± 6.8 nm primary size, mean total Ag concentration 41.14 mg/L, 46–68% of soluble Ag⁺-species in stock, 123.8 ± 12.2 nm mean z-average value in dH₂O) showed extreme toxicity to crustaceans Daphnia magna, algae Pseudokirchneriella subcapitata and zebrafish Danio rerio embryos (EC50 < 0.01 mg total Ag/L), was very toxic in the in vitro assay with rainbow trout Oncorhynchus mykiss gut cells (EC50: 0.01–1 mg total Ag/L); toxic to bacteria Vibrio fischeri, protozoa Tetrahymena thermophila (EC50: 1–10 mg total Ag/L) and harmful to marine crustaceans Artemia franciscana (EC50: 10–100 mg total Ag/L). Along with AgNPs, also the toxicity of AgNO₃ was analyzed. The toxicity data revealed the same hazard ranking for AgNPs and AgNO₃ (i.e. the EC50 values were in the same order of magnitude) proving the importance of soluble Ag⁺-species analysis for predicting the hazard of AgNPs. The study clearly points to the need for harmonised procedures for the characterisation of NMs. Harmonised procedures should consider: (i) measuring the AgNP properties like hydrodynamic size and metal ions species in each toxicity test medium at a range of concentrations, and (ii) including soluble metal salt control both in toxicity testing as well as in Ag⁺-species measurements. The present study is among the first nanomaterial interlaboratory comparison studies with the aim to improve the hazard identification testing protocols.     

The Economic Consequences of Alien Plant Invasions: Examples of Impacts and Approaches to Sustainable Management in South Africa

The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work has been done on the economic aspects and consequences of invasions. This paper reviews what is known of the economic consequences of alien plant invasions in South Africa. These economic arguments have been used to successfully launch the largest environmental management programme in Africa.Ten million hectares of South Africa has been invaded by 180 alien species, but their impacts are not fully understood, although they are undoubtedly significant. The indications are that the total costs of these impacts are substantial. Selected studies show that invasions have reduced the value of fynbos ecosystems by over US$ 11.75 billion; that the total cost of invasion would be about US$ 3.2 billion on the Agulhas Plain alone; that the net present cost of invasion by black wattles amounts to US$ 1.4 billion; that invasions by red water fern have cost US$ 58 million; and that the cost to clear the alien plant invasions in South Africa is around US$ 1.2 billion. These few examples indicate that the economic consequences of invasions are huge.One of the unique aspects of invasive plant control programmes in South Africa has been the ability to leverage further benefits (mainly through employment) for the expensive control programmes from the government's poverty relief budget. This has made it possible to allocate substantial funding to a programme that would otherwise have struggled to obtain significant support. Biological control of invasive species also offers considerable benefits, but is often the subject of debate. We believe that, at least in the case of many invasive alien plant species in South Africa, biological control offers one of the best, and most cost-effective, interventions for addressing the problem.     

Morphological relationships of the Wheatears (genus Oenanthe)

The genus Oenanthe comprises approximately 22 species, of which 16 species are restricted to the desert belt of the Palaearctic and Afrotropic regions, where they are often the most conspicuous passerines. Although they have been the subjects of some morphological and ecological studies, no complete morphometrical data has been used to verify their taxonomic relationships, and, the species relationships are still debated. Overall morphometrical similarities between Wheatears and their relationships in size and shape were assessed using measurements of 27 biometrical variables on 417 museum specimens. The 22 Wheatear species comprise some morphological groups: long migratory vegetation-tolerant species (O. pleschanka, O. hispanica, O. cypriaca and O. deserti), ground-dwelling migratory (O. isabellina and O. oenanthe), and sedentary (O. bottae, O. heuglini and O. pileata) of steppe-like habitants, relatively heavy and rock-dwelling species (O. leucura and O. monticola), inhabiting the most arid areas (O. monacha, O. leucopyga and O. alboniger), and finally a central core of medium-sized partial migrants, largely overlapping in morphometric space, that do not present any evident specialization (O. lugens, O. chrysopygia, O. xanthoprymna and O. finschii). It seems Wheatear species are well distributed in a morpho-space of size and shape with moderate overlaps and few hiatuses corresponding to a morphological continuum of species. Furthermore, our results largely hiatuses corresponding to a morphological continuum of species. Furthermore, our results largely differ from previous phylogenetic hypotheses (based on ecological, behavioural, and chromatic characters), but, are in congruence with molecular data.     

Characteristics of parasitic infection in the least cisco, Coregonus sardinella valenciennes, 1848, in the Ural tributaries of the lower Ob

Data on the parasite fauna of the least cisco, Coregonus sardinella Valenciennes, 1848 in Ural tributaries of the Ob downstream of the city of Salekhard have been obtained for the first time. The formation patterns of the parasite fauna in this species and the rate (prevalence and intensity) of infection by Ichthyocotylurus erraticus (Odening, 1969), a parasite specific to coregonids, have been revealed. Infection of the least cisco with six parasite species (out of the 12 species found) occurs as the fish feed on zooplankton and benthic organisms. The dominant parasites are trematode larvae of the genera Ichthyocotylurus and, in some years, Diplostomum; this composition of dominants is evidence that the least cisco fattens up mainly in shallow areas. All sexually mature fish of this species were found to be infected by I. erraticus, but the average intensity of infection was rather low: the abundance index of the parasite did not exceed 40 ind. per fish. Analysis of the distribution of I. erraticus metacercariae in the least cisco shows that the relationship in the host-parasite system is stable and the parasite has no pathogenic effect on individuals of older age classes.     

外来种入侵对乡土生物多样性的影响机制

外来种入侵是全球性变化研究的重要组成部分,已经成为各国生物多样性保 护和管理的核心问题。近年来,大多数人给予了外来种对生态系统的负面作用充分的论述和研究,而忽视了它们的积极效应。如何客观辨证地评价外来种的作用和可能的影响是规避和管理外来种所带来的风险的前提和保障。在综述外来种、乡土种和外来种入侵的基本概念及其危害情况的基础上,系统阐述了外来种侵入和种群扩大对生物多样性所带来的正负两方面的影响。外来种入侵可能的影响途径及其机制主要包括：（1）竞争与排斥;(2）杂交;（3）打断或改变食物链关系;（4）带入病毒等。外来种入侵对乡土物种多样性的影响途径和机制实际上是上述众多因素综合作用的结果。外来种之所以给生态系统和人 类带来危害和损失,根本原因在于人们缺乏外来种入侵的相关知识以及预防手段和意识,更缺乏对外来种的有效管理。规避外来种所带来的风险,最关键是要尽可能地避免人为的、有意的协助外来种的入侵,并在做好各种安全措施后,有计划、有步骤地慎重引入,科学管理,规划发展。目前对外来种入侵的生态学知识还是零碎的、局部的、表象的,深入研究外来种的生物学生态学特性及其入侵的生态学机制是当前最为急迫的工作。建议我国近期加强外来种的本底调查与现状评估、外来种入侵的通道与入侵过程及其影响因素、外来种入侵的生态过程及其效应以及外来种入侵的进化后果等方面的工作。     

Saturation and invasion resistance of non-interactive plant communities

Open plant assemblages in shoals of western Caucasian rivers were used as examples to analyze the relationship between the species saturation and the number and total abundance of alien species in non-interactive communities. Invasion of exotic species into highly saturated communities has been demonstrated to be, on average, less probable than their invasion into unsaturated communities. A hypothesis explaining the relationship between these parameters has been put forward. According to the hypothesis, the number of alien species in a specific locality in a community is determined by their ratio to the number of native species in the species pools of these communities; and their mean abundance, by the ratio of the total number of species to the number of individuals in the localities. Both ratios are smaller in saturated biocenoses, which determines a relatively small admixture of alien species in them.     

Ecological and faunistic characteristics of the leech fauna in the Bukhtarma Reservoir,Eastern Kazakhstan

The taxonomic diversity of the Hirudinea fauna and its dependence on the ecological conditions in the Bukhtarma Reservoir (Eastern Kazakhstan) have been studied. The morphological analysis has shown that these leeches belong to two orders and three families: Rhynchobdellida (families Glossiphoniidae and Piscicolidae) and Arhynchobdellida (family Erpobdellidae). On the whole, eight leech species from five genera (Alboglossiphonia, Helobdella, Theromyzon, Piscicola, and Erpobdella) have been identified. Among them, there are three glossiphoniid species (A. heteroclite, H. stagnalis, and T. tessulatum), two species of piscicolids (Piscicola geometra and Piscicola sp.), and three species of predatory leeches (E. octoculata, E. vilnensis, and Erpobdella sp.). Possible effects of hydrochemical parameters of the aquatic environment on the species diversity have been analyzed. Correlation has been revealed between the abundance of species and the physical and chemical characteristics of the environment.     

Spatial distribution and karyotypic composition of Anopheles mosquitoes (Diptera, Culicidae) in the environs of Teletskoye Lake

The species composition and inversion structure of Anopheles micropopulations have been studied in the environs of Teletskoye Lake, the Altai Republic. Two Anopheles species, A. messeae and A. beklemishevi, have been identified cytogenetically: Their zonal distribution has been determined, reflecting specific climatic features in the southern and northern parts of the lake. Intraspecific chromosomal polymorphism has been revealed in both mosquito species, with the inversion and karyotypic diversity being higher in the southern larval populations of A. messeae.     

Ecological preferences of forest voles

Basic climatic parameters (annual average air temperature and annual amount of precipitation) over 12–25 years have been analyzed with regard to their values corresponding to different levels of abundance in three species of forest voles: Clethrionomys glareolus (in 11 areas of the species range), Cl. rutilus, and Cl. rufocanus (in three areas each). The results show that the abundance of all these species correlates significantly with fluctuations of annual average temperature, with the correlation being negative in Cl. glareolus and Cl. rufocanus but positive in Cl. rutilus. In addition, the abundance of Cl. rufocanus shows a significant correlation with annual precipitation. Voles inhabiting different geographic regions may reach high abundance under different conditions. As for the species range as a whole, however, Cl. glareolus is more ecologically flexible than the other two voles. This species is also more warmth- and moisture-loving, while Cl. rufocanus is more cold-loving and xerophilous, with Cl. rutilus occupying an intermediate position between them. Clethrionomys rutilus is most temperature-dependent and stenothermic among them, whereas Cl. glareolus is indifferent to the factors studied.     

Factors of Richness of Urban Floras in the Ural–Volga Region

Original data on 14 urban floras in the Ural–Volga region have been analyzed to estimate the effect of the geographic location, topography, climate, size, and age of a city on the species richness of its flora. This parameter in different cities varied from 288 to 973 species, with the proportion of alien species varying from 21 to 41%. Factors of flora richness were estimated by multiple linear regression using principal component estimates obtained by factor analysis of 13 city characteristics as predictors. It has been confirmed that the richness of urban floras depends primarily on the city size, which accounts for greater proportions of variation in the number of native species (56%), the number of alien species (91%), and the total number of species (71%). In addition, variation in the number of native species is determined by terrain elevation (22%), increasing at higher elevations. The proportion of alien species in the urban flora does not depend on the size of the city and is negatively correlated with terrain elevation.