Том 9, № 1 (2016)

Comparative study of somatic musculature in illoricate rotifer Asplanchina girodi Guerne, 1888 and loricate Trichotria pocillum (Müller, 1776) has been carried out by the method of phalloidin fluorescence and confocal laser scanning microscopy. Similar layering of muscles is revealed, while significant differences are observed in other aspects. Postcoronal transverse muscle of A. girodi and the dorsal portion of the anterior circular muscle of T. pocillum serve as attachment sites for the refractor muscles. All retractors are formed by smooth muscles or striated muscles, except the lateral retractors of A. girodi, which are formed by the most powerful oblique muscles. In A. girodi there are three pairs of retractors, ten longitudinal muscles, and five circular muscles, with a thick muscular plexus connecting them. In T. pocillum there are four pairs of retractors, five transverse muscles, strong foot retractors, and an arched structure of the head region (new for rotifers). Eight pairs of dorsoventral muscles, as identified in T. pocillum, are completely absent in A. girodi.

The results of studies on the structure of vegetative organs of Stratiotes aloides L. are presented. An organographic analysis and detailed morphological and anatomical descriptions of the root system, shoot system, and inflorescences have been made. It is demonstrated that the S. aloides shoot system is characterized by high vegetative mobility. The main histological topographical complexes, their proportions, and histochemical features are determined. The shoot system of S. aloides is characterized by underdeveloped xylem. Lignification of the epidermal and exodermal cell wall is a compensatory adaptation providing additional reinforcing properties. The development of diffuse collenchyma and general aerenchymatization of S. aloides tissues are effective mechanisms of adaptations to the aquatic habitat.

The results of the comparison of the Lower Amur grayling Thymallus tugarinae and the yellowspotted grayling T. flavomaculatus that were collected in the zone of their sympatry in the middle reaches of the Anuy River (the Lower Amur basin) for a number of osteological and morphological features are provided. The work was based on the analysis of X-ray images and a number of plastic features. Considerable differences were detected between the two species in the numbers of the bone elements of the axial skeleton. The differences in the number and topography of certain bone elements correlate with the morphological features of these species. The comparison results for certain features do not correspond with the literature data.

The results of a study on some parameters of innate immunity and oxidative processes in hepatopancreas of the chub Leuciscus cephalus (L.) inhabiting the river ecosystems of Krasnodar krai and Abkhasia subjected to different degrees of anthropogenic load are presented. Antimicrobial properties of blood serum, the content of nonspecific immune complexes in the liver, and the level of total lipids and antioxidant activity have been studied. It is determined that the portion of immunodeficient specimens is higher in samples from polluted waters than from unpolluted areas. Fishes caught in the river subjected to high anthropogenic load contained higher concentrations of products of lipid peroxidation and immune complexes and had lower levels of antioxidants.

Qualitative and quantitative structures of benthic macro-invertebrates, macrophytes, zooplankton, as well as ichthyofauna and fish parasites of the shallow areas of Small Sevan that flooded as a result of an increase in the lake’s water level are analyzed. It is shown that the most appropriate conditions for the development of hydrobionts were found in the area that was flooded earlier and is directly connected with the lake. In contrast, the worst conditions occurred in the area that was flooded later and is minimally connected with the lake.

A total of 290 species and varieties of Bacillariophyta including 32 that were new for the flora of Karelia and 18 that were new for the flora of Russia, have been recorded in phytoplankton in nine rivers of the White Sea basin. The genera Aulacoseira, Pinnularia, Eunotia, and Navicula s. l. are the richest in taxonomy. The maximum species diversity was recorded in the Suma (73), Kolezhma (91), and Chirko-Kem (146) rivers. The following species are the most widespread in the rivers that were under study here: A. ambigua, A. subarctica, A. subborealis, {tiA. tenella}, Asterionella formosa, and Tabellaria flocculosa.

The basic patterns of the spatial structure of phytoplankton in large oligotrophic rivers of northeastern Siberia were determined using principle component analysis (PCA), factor analysis, and cluster analysis. It was found that in extreme conditions of oligotrophic subarctic rivers the formation of the spatial structure of the phytoplankton generally occurs under the influence of climate, rather than physicochemical water properties. Among the developmental parameters of the phytoplankton, the floristic structure of phytoplankton is the most dependent on the abiotic factor.

Features of the composition and structure of the summer zooplankton in the pelagic zone of Lake Sevan in years that were characterized by different abundances and biomasses of fish are described. It is shown that the species diversity of the community and the specific number of species of zooplankteurs, the quantity of Copepods in the total abundance and biomass of zooplankton, as well as the value of the Shannon index and the trophic coefficient, increased upon an increase in the fish abundance. At the same time, the total biomass of zooplankton and biomass of cladocerans decreased, among which the density and biomass of the larger and more colored Daphnia (Ctenodaphnia) magna Straus decreased, but the density and biomass of D. (Daphnia) hyalina Leydig and Diaphаnosoma brachyurum Lievin increased.

The possible causes of the invasion of the black-striped pipefish Sygnathus nigrolineatus Eichwald, 1831 into two water reservoirs of the Dnieper Cascade of Hydroelectric Stations are described. The average, maximum, and minimum specific rates of the change of the abundance of the species in the recipient water bodies are analyzed since the onset of the invasion. Specification of different phases of naturalization is based on the analysis of dynamic phase portraits of the species abundance. The periods of the equilibrium states of the population are revealed. The potential rates of the increase of the species abundance in the Dneprodzerzhinsk and Kremenchug reservoirs are assessed.

The influence of the sampling and processing-method accuracy on the bioindication parameters of the taxonomic and size structure of the phytoplankton community, fluorescence, and saprobic index has been studied in Rybinsk Reservoir. The studied parameters have been ranked in accordance to their sensitivity to the method accuracy. The comparative analysis of the relative errors of the studied parameters has been performed for Rybinsk Reservoir and the White Sea phytoplankton communities. Recommendations about the most useful parameters to assess the status of the phytoplankton community are given.

The data on a finding of the topmouth gudgeon in an irrigation canal of the Kodori River in the Republic of Abkhazia in August of 2015 are presented.