Том 10, № 4 (2017)

The aquatic microecosystems and their environment have been studied in 12 mineral springs located in the Cis-Baikal Depression and in the basin of the upper reaches of the Lena River (Eastern Siberia). The hydrochemical characteristics of the springs, originating from the Cambrian salt deposits, are given. Their total mineralization varies from 1.1 to 123.0 g/L and the water is sodium chloride. The soils formed under the influence of the mineral waters (“para-soils”) are described. The data on the composition and quantitative abundance of aquatic fauna are presented. Six types of macroinvertebrate communities are described. The communities where Turbellaria, Gastropoda, and Psychodidae dominate are recorded in weakly mineralized waters (<3 g/L). The communities where Chironomidae dominate are found in waters characterized both by low and high (up to 28 g/L) salinity. In springs with a water salinity of 2.5–11 g/L, communities characterized by the dominance and high biomass of amphipods Gammarus lacustris Sars. are formed. A unique type of community where Ephydridae larvae dominate (>97% of the biomass) is described for the concentrated brines in Ust’-Kutskii spring. Halophilic species of crustaceans are recorded in the meiofauna. The presence of Foraminifera (marine organisms) in the two studied springs attracts specific interest.

A study of the phytoplankton of the water bodies and watercourses in the Yarayakha River and Naduiyakha River basins (the Yamal Peninsula) has revealed a wide morphological variability of the quantitative diagnostic features in Parlibellus crucicula: valve length and width, the number of striae and areolae in 10 μm, and the stria density in the middle part of the valve. A number of the features (raphe structure, presence of pseudosepta, and obliquely oriented oval areolae) typical for the genus Prestauroneis have been found in Parlibellus crucicula. This makes it possible to define this species as belonging to the genus Prestauroneis and to form a new combination, Prestauroneis crucicula (W. Smith) Genkal et Yarushina comb. nov.

Dynamics of the species structure of Cladocera based on the materials on bottom sediments has been studied for 3000- and 6000-year periods in two lakes. The community of one of these lakes has reached a dynamic climax, and the community of the other lake is at the stage of directing succession. The species structure of both communities is approximated well by the Motomura–Whittaker equation (i.e., model of geometrical series). For each of the studied lakes, the main parameter of this model (the coefficient of geometrical progression) does not differ significantly from its theoretically derived value equaled to 1–exp(–1) = 0.632. A stable relationship is found between species diversity of the community, the rate of ecological succession, and the coefficient of geometrical progression.

The data on seasonal and interannual changes in the taxonomic, structural, and quantitative characteristics of macrozoobenthos communities in rivers with a high salinity gradient are given. A total of 91 benthic invertebrate taxa have been revealed, which were dominated by Cricotopus salinophilus, Chironomus salinarius, C. aprilinus, Tanytarsus kharaensis, Microchironomus deribae, Glyptotendipes salinus (Diptera: Chironomidae), Culicoides (M.) riethi, Palpomyia schmidti (Diptera: Ceratopogonidae), Paranais simplex (Oligochaeta), and Ephydra sp. (Ephydridae) in different years. The fauna of benthic communities is mainly represented by eurybiontic halotolerant species with different ranges of resistance to salinity. The taxonomic composition and diversity of macrozoobenthos communities are closely correlated with water salinity in the range from 4 to 41 g/L; the complex of hydrological and hydrophysical factors (depth, overgrowing, water temperature, pH, etc.) control the distribution and abundance of species.

The composition of bottom invertebrates in rocky rapids and riffles in rivers of the White, Barents, and Baltic seas in the territory of Eastern Fennoscandia is presented and analyzed. A total of 114 species (137 taxa of different ranks) have been identified. Most of them have Euro-Siberian (44%) and Palaearctic (36%) distribution. Regarding the feeding mode, collector–gatherers (32%) and collector–filterers (25%) dominate among trophic groups. Differences in the composition of zoobenthos between the southern and northern parts of the region can be explained not by the fauna genesis, but by latitudinal zoning.

After 30 years of intensive walleye pollock fishing in the Sea of Japan and the Sea of Okhotsk, the average number of vertebrae has increased significantly in the caudal section of the spinal column. The maximum frequency of occurrence of “multivertebrae” phenotype (33 caudal vertebrae) has increased from 3–5 to 76–78%. The number and frequency of occurrence of the abdominal vertebrae did not change. Experimental testing of walleye pollock on its ability to resist the flow justifies our suggestion that the number of vertebrae in the caudal section is an important adaptive feature. We argue that the changes in phenotypic structure of the studied population are the result of intensive fishing.

For the first time, a morphometric description of the rudd Scardinius erythrophthalmus (Linnaeus) in the backwater zone of the Shumarovka River influenced by the Rybinsk Reservoir and lakes Chistoye and Sankhar is presented. The rudd from the Shumarovka River belongs to the generation of the anomalously warm year 2010. According to a combination of analyzed features, the rudd from the Shumarovka River is similar to the fish of this species of Lake Chistoye, but differs from the rudd of the karst Lake Sankhar. The study suggests that scale initiation and formation in the lateral line and the number of pores of the seismosensory system in rudd depends on the rates of its development and growth at its early life stage.