Phytoplankton of some rivers in the south of broadleaved forests subzone of the Middle Volga basin in a long-term perspective

The paper provides information on the composition, structure and dynamics of phytoplankton of three morphologically different tributaries of the Cheboksary reservoir (the Vetluga, the Kerzhenets and the Vishnya rivers). The species composition of algae includes 826 species and intraspecific taxa, the flora was formed by diatom, green and euglena algae. It reflects the watercourses particularities of the southern taiga zone. Based on long-term studies of phytoplankton a change in the composition of algoflora by more than half was noticed, especially in the groups of Charophyta, Cryptophyta, Miozoa, Ochrophyta and Euglenophyta. An increase in quantitative indicators of algocoenoses from oligotrophic to oligotrophic-mesotrophic level in the middle reaches of rivers by mesotrophic-eutrophic level in estuarine areas is shown. In a fifty-year research series a tendency of phytoplankton reduction in size by more than 3,5 times has been established. It reflects the impact of eutrophication and gradual warming of the climate. The period of abnormally hot summer of 2010 led to increased vegetation in the middle reaches of rivers of diazotrophic blue-green algae and dinophytes. Since the early 2000s, gradual penetration and naturalization of both planktonic invasive algae species and representatives of benthic algocoenoses have been noticed. The mentioned changes reflect the nature of phytoplankton rearrangements as the essential component of the biota and emphasize the importance of long-term research with a possibility to predict negative consequences.

Morphological characteristics of Kellicottia bostoniensis (Rousselet, 1908) (Rotifera: Brachionidae) in water bodies of the Middle Volga basin

The morphological characteristics of the North American invasive species Kellicottia bostoniensis Rousselet, 1908 were studied in 29 various types of water bodies and watercourses of the Middle Volga basin. The water bodies, which are the habitats of K. bostoniensis, are located on several territories that differ significantly in a set of characteristics, such as their geological structure, relief, climate, anthropogenic impact, hydrochemical and hydrophysical indicators, etc. The sizes of K. bostoniensis individuals in most of the studied water bodies and watercourses were measured and analyzed for the first time. A high positive correlation was found between the total body length and the posterior spine length (R2 = 0.79, p < 0.01), as well as the anterior spine length (R2 = 0.75, p < 0.01). A relationship was revealed between the lengths of the anterior and posterior spines (R2 = 0.58, p < 0.01). K. bostoniensis individuals in the studied water bodies and watercourses are characterized by large sizes, the median values of the total body length being 236–440 μm. These sizes are similar to those of individuals in the native habitats of North America and some biotopes of Europe and European Russia. Among the previously studied water bodies of Russia and other countries (Belarus, Sweden, Finland, Brazil, and Argentina), where researches of the morphological variability of K. bostoniensis were carried out, the largest body sizes were characteristic for the invader species of the Sura River. Larger K. bostoniensis specimens live in deep mesotrophic water bodies with high transparency, compared with representatives of this species in shallow eutrophic water bodies with less transparency in the Middle Volga basin. Our data on the morphological characteristics of the invading species of water bodies in the Middle Volga basin significantly expand the existing information on the morphological variability of K. bostoniensis individuals and their dependence on environmental factors.

Indicator role of the ontogenetic structure of rare plant cenotic populations in the assessment of the ecological state of species under anthropogenic pressure (for example, Rindera tetraspis Pall)

The study of population structure, including ratios in different ontogenetic groups of individuals, provides unique information for the development of express methods of determining the ecological state of natural complexes. Data on population structure, dynamics of population indicators and other bioecological features allow to determine more precisely the need for protection of different species at regional and more global levels. The purpose of this research is to determine the ontogenetic structure of natural populations of rare plant species. The example of Rindera tetraspis Pall. was used to establish changes in ontogenetic structure of local populations under anthropogenic pressure on species’ habitats (on the territory of the Middle Volga basin, Russia). A decrease in the ability to self-sustain the number of individuals and aging of the population at cattle grazing and steppe fires have been revealed.

Ontogenetic structure and types of cenopopulation of Hedysarum grandiflorum Pall. in the Middle Volga basin

. The need to study the current state of cenotic populations of rare plant species in nature is not in doubt for the conservation of floristic and phytocenotic diversity at the regional and world levels. The purpose of our study is to study the current state of the cenotic populations of Rare in the Middle Volga basin Hedysarum grandiflorum Pall. To characterize the ontogenetic structure of the cenopopulations, generally accepted demographic indicators were used: the recovery index (the ratio of growth to the generative fraction is calculated), the replacement index (the ratio of growth and the sum of generative and post-regenerative fractions), and the aging index (post-generative to the adult part of the cenotic populations). The population estimation was carried out by the criterion “delta-omega”.A relatively narrow range of ecological and phytocoenotic growth conditions is characteristic of the species, for the most part a patient type of life strategy. Among the limiting factors for the development of populations of environmental factors are their location at the border of the area, uncontrolled grazing in areas, excessive recreation of territories and steppe fires (natural origin and pala) in phytocenoses with the participation of a penny, career development of limestone and Cretaceous slopes, and construction debris, the appearance of dirt roads and the construction of various objects in the points of growth of the model species.The main ways of ontogenesis of the species are identified – normal, accelerated and delayed, breaks in the development of individuals, their rejuvenation and the manifestation of quasisenity were noted. The majority of H. grandiflorum develop at a normal and accelerated rate. The main indicator for determining the current state of populations and their loci is the ontogenetic structure. As an example, information on the ontogenetic composition of some cenopopulations of H. grandiflorum at the Chubovskaya Krasnaya Gorka (High Samara Zavolzhye, Russia) is given. Populations are characterized by the predominance of generative individuals. Of the registered cenopopulations, 11 is characterized as mature, 9 – transitional, 2 – ripening, 1 – young. Aggregation is characteristic of the spatial structure of H. grandiflorum.

Летописная ойконимия как источник реконструкции лексики древнерусского языка

Annalistic oikonymy as a source for reconstruction of the Old Russian vocabularyAmong about 1,000 place names mentioned in the Old Russian chronicles (within the borders of contemporary Russia), there are 19 ones that are derived from stems non-attested as apellatives in the Old Russian written sources. The vast majority of them can be reconstructed by comparison with words of modern East Slavic languages or their dialects, but several are not known in the East Slavic zone, and have parallels in the West and (or) South Slavic languages only. Almost all of these words are geographical terms. The places in whose names they are preserved are located mostly in Novgorod Ruthenia and the Upper and Middle Volga basin. Ojkonimia latopisów jako źródło dla rekonstrukcji słownictwa języka staroruskiegoWśród około 1000 nazw miejscowych wymienionych w staroruskich kronikach (w granicach dzisiejszego państwa rosyjskiego) jest 19 pochodzących od podstaw, które nie są apelatywnie poświadczone w źródłach staroruskich. Zdecydowaną większość z nich można zrekonstruować na podstawie wyrazów należących do zasobu leksykalnego współczesnych języków wschodniosłowiańskich lub ich dialektów, ale kilka z nich ma analogie tylko w językach zachodnio- i południowosłowiańskich. Prawie wszystkie te słowa są terminami topograficznymi. Miejsca, w których nazwy są zachowane, znajdują się głównie w Rusi Nowogrodzkiej i dorzeczu Górnej i Środkowej Wołgi.

Report on two rare Myostenostomum species (Platyhelminthes: Catenulida) from the Volga River Basin

Two rare catenulid species, Myostenostomum vanderlandi Rogozin, 1992 and M. bulbocaudatum Luther, 1960, were found in reservoirs of the Volga-Kama Biosphere Reserve (Middle Volga Basin, Russia) during a survey of microturbellaria in 2013. Both the species were recorded for the first time in the fauna of the Volga Basin, while M. vanderlandi, previously known only from water bodies of South America, was first found in the Holarctic. The morphological characters and geographical distribution of the species are discussed.