Successions of zooperiphyton in a small river

In the small Latka River, which is characterized by a high heterogeneity of abiotic characteristics and a rich fauna composition, a high diversity of developing zooperiphyton structures was recorded consisting of invertebrates with short life cycles: the larvae of chironomids, caddisflies, mayflies, oligochaetes, nematodes, and other animals. One distinctive feature of seasonal and interannual zooperiphyton succession is the annual prevalence in abundance of spreading chironomid larvae of age I, which belong to the most representative dominating group of amphibiotic invertebrates, including species adapted to different saprobic conditions. The taxonomic and quantitative domination of chironomids make it possible to consider the family Chironomidae a key group in the formation of the zoocenosis structure. Under disturbed habitat conditions (pollution, rainfall floods, and the press of omnivorous invertebrates), the restoration of typical structures occurs rather quickly due to the particular features of biology in species short life cycles. However, no relative stabilization in communities was observed. This is the main difference between the sequence of succession processes in the Latka River and that observed in large water bodies (lakes and water reservoirs), where there are no strict limitations on living-space volume or food availability and abiotic conditions are more stable, thus allowing filter-feeding sessile animals (sponges, bryozoans, and zebra mussels) to develop on solid substrates. These species are able to develop multispecies consortia and form relatively stable long-term communities.     

Study on zooperiphyton and zoobenthos of a small river

The special traits of zooperiphyton and zoobenthos structures in a small river were studied. Under conditions of maximal proximity of niches, these groups of invertebrates retain taxonomic and ecological heterogeneity. Differences in zooperiphyton and zoobenthos taxonomic structures are most pronounced in terms of presence of dipterans, oligochetes, and mollusks. In the periphyton, the dominant groups are chironomid (orthocladines, chironomines, and tanitarsines) larvae, oligochetes of fam. Naididae and mollusks of fam. Limnaeidae. In the benthos chironomid (chironomines and tanirodines), oligochetes of fam. Tubificidae, and mollusks of fam. Pisidiidae are dominant. On average, the bottom invertebrates are considerably larger than fouling organisms. At similar abundance values, the biomass of benthos is by an order of magnitude higher compared to zooperiphyton. Ranging of average biomasses of zooperiphyton and zoobenthos revealed that the leader common for both communities is the large and mobile predatory leech, Erpobdella octoculata (Linnaeus). The anthropogenic impact and zoogenic (beavers) impact upon the river biota are comparable to each other.     

Changes in the zooperiphyton structure in a small river along the spatial gradient

A total of 165 taxa have been recorded in the zooperiphyton of the Sestra River, among which larvae of chironomids (40), nematodes (24), and oligochaetes (21) have the highest species richness. The increase in the taxonomic richness of zoocenoses from the river head to its mouth is weakly expressed. The highest diversity of zoocenoses is characteristic for the contact zones of the river water with its tributaries and receiving waters. The discreteness of spatial characteristic of the taxonomic composition of zooperiphyton reflects the heterogeneity and diversity of habitat conditions of invertebrates. In regards to its effect on zoocenoses, anthropogenic pollution can exceed the impact of many environmental factors (including the current velocities) which affect the formation of rheophilic communities in river ecosystems. The dominant complexes of zooperiphyton include all trophic groups of invertebrates, among which the group of detritophages-collectors has the highest taxonomic diversity. The group of phytodetritophages-filterers + collectors mainly includes chironomid larvae of the genus Chironomus, which are associated with strongly polluted zones. Invertebrate filterers, sponges, and bryozoans prevail mainly in zooperiphyton in the lower reaches of the river, which are not subjected to the pollution.     

Peculiarities of the zooperiphyton succession in beaver ponds of a small river

The increase in the species diversity of the zooperiphyton and intensifying succession due to the increase of the abundance of chironomid larvae (stage I) was observed upstream along the small Latka River (a tributary of Rybinsk Reservoir) during the first year after the appearance of the beaver dam, when the depth increased and the flow velocity decreased. In the beaver pond, which was overgrown by yellow water-lily, the zoocenose succession depended greatly on the abundance of the vegetating and fading plants. During the vegetation period, at high abundance of the yellow water-lily, the species richness of the zoocenose decreased, and then it increased again the next year, when new vegetation was low, and the old plants were decomposing en masse. Directly downstream from one of the beaver dams, the mollusks affected negatively the seasonal succession of the zoocenoses under an instable water level and current regime, when they removed nearly all the fouling from the substrates.     

Spatial structure of zooperiphyton from the Ob River

Data on the qualitative and quantitative composition of zooperiphyton in the middle and lower reaches of the Ob River are reported, revealing the basic factors affecting its growth. Along most of the river, the zooperiphyton forms a continuum, which is disturbed at sites exposed to pollution. It is found that communities dominated by caddisworms prevail over most of the river; a decrease in the river stream velocity causes a change in the communities, with the replacement of Trichoptera by gastropod communities.     

Basic characteristics of zooperiphyton in large rivers of Western Siberia (Tyumen oblast)

The data on the qualitative and quantitative composition of zooperiphyton from seven large rivers of Western Siberia are presented. The species similarity of zooperiphyton has been documented in most of the rivers. The biomass in unpolluted parts is mainly formed by the larvae of caddis flies. Factors which effect the composition and structure of zooperiphyton have been determined. Changes in the structure and quantitative development of zooperiphyton are shown.     

Spatial and typological inhomogeneity of small mammal communities in plains and mountains of West Siberia

The paper reports results of analysis of spatial and typological inhomogeneity in small mammal communities of the West Siberian Plain and Altai as compared with that in amphibian, reptile, and bird communities.     

Ostracods (Crustacea and Ostracoda) in the zooperiphyton of waterbodies and watercourses of Tyumen oblast (Western Siberia)

The species composition of ostracods in the zooperiphyton was determined in 45 waterbodies and watercourses of Tyumen oblast. A total of 58 species from seven families and 22 genera of the suborder Podocopa Sars, 1866, have been found: 30 species of the family Candonidae, 13 of Cyprididae, 8 of Cyridopsidae, 3 of Ilyocyprididae, 1 of Darwinulidae, 2 of Cytherideidae, and 1 of Limnocytheridae. Of these 58 species, 32 are recorded for the first time in the region; one of them is a Mediterranean species (Stenocypris sp.) from the cooling reservoir of Tyumen Thermal Power Station 1. The distribution and biogeography of the ostracods are described.     

Transport of mercury by the Katun river,West Siberia

Some results of a 2-year study of mercury pollution of the Katun river (Siberia) are summarised. Measurements of water flow, sediment transport and mercury concentrations were made and used to calculate the amount of mercury transported by the river. The distribution of transport between water phase and suspended material is calculated. It is concluded that suspended sediments play the main role in this process. The significance of different fractions of suspended sediment is also discussed.     

Spatial Distribution of Species Diversity of Clavarioid Mycobiota in West Siberia

The results of a 20-year study of the spatial distribution of clavarioid mycobiota in the West Siberian Plain (WSP) are discussed. The species structure has been studied on two scales: regional (an area of 100000 km²) and local (100 km²). In the studied area, 121 species of clavarioid fungi are found. The patterns of spatial variability of species diversity on the plain are revealed. On the regional scale, the maximum species richness of fungi is observed in hemiboreal forests (104 species); on the local scale it ranges from the middle boreal to hemiboreal (54.3–54.5 species). With the increasing pessimality of the hydrothermal regime, the number of species decreases sharply on both scales in the direction of the tundra and steppes. The study of the distribution of diversity among the localities reveals changes not only along the latitudinal gradient, but also in the longitude sectors: in the forest zone, the richest localities are located on the western and eastern edges of the plain, while in the extensive marshy areas in the center the number of species is lower (p < 0.05). A map of the spatial distribution of species diversity for the local scale is constructed. The correspondence of the spatial distribution of the studied fungi group to a global latitudinal gradient is discussed. The main abiotic factors forming a variety of the studied group of fungi in the region are revealed.     

Spatial heterogeneity of periphytic microbial communities in a small pesticide-polluted river

Spatial variability in the microbial community composition of river biofilms was investigated in a small river using two spatial scales: one monitored the upstream–downstream pesticide contamination gradient, referred to as the 'between-section variability', and the other monitored a 100-m longitudinal transect (eight sampling sites per section) within each sampling section, referred to as the 'within-section variability'. Periphyton samples were collected in spring and winter on artificial substrates placed in the main channel of the river. Denaturing gradient gel electrophoresis (DGGE) was used to assess the prokaryotic and eukaryotic community richness and diversity, and HPLC pigment analysis to assess the global taxonomic composition of the photoautotrophic community. In order to try to reduce the biological variability due to differences in flow velocity and in light conditions within each sampling section, and consequently to take into account only the changes due to water chemistry, nine plates (three per sampling section) subjected to similar physical conditions were chosen, and the results for these plates were compared with those obtained for all 24 plates. As shown by DGGE and by HPLC analyses, using these three substrate plates exposed to similar environmental conditions did indeed reduce the within-section variability and maximize the between-section variability. This sampling strategy also improved the evaluation of the impact of pollutants on the periphytic communities, measured using short-term sensitivity testing.     

Spatial-typological structure and mapping of reptile population of West Siberia

West Siberian reptiles were studied on the basis of the materials collected in forest, forest-steppe, and steppe zones of the Ob’ region during 12 years. Their abundance in certain biotopes has been determined. The relationship between the heterogeneity of reptile community and basic structure-forming environmental factors has been estimated, and a map of population of this faunal class was compiled.     

Spatial microhabitat selection by Biomphalaria pfeifferi in a small perennial river in Tanzania

A study was carried out in the Mlali river in south-central Tanzania with two aims. First, to determine microhabitat availability in two sites (A and B) with respect to water depth, water velocity and dominant substratum type. Second, to assess microhabitat use by Biomphalaria pfeifferi, the intermediate host snail of intestinal schistosomiasis and to investigate whether these snails show preferences for certain microhabitats. The two sites differed significantly with respect to width, water depth, water velocity and substratum composition. It is suggested that the absence of B. pfeifferi from site B is mainly associated with the high water velocities at that site, where 62% of the measurements exceeded30 cm s^-1. In site A, the microhabitat use by 327 B. pfeifferi snails was assessed by means of direct observation. No significant relationships were found between snail size and the habitat variables investigated, indicating that snail size appeared to be of no importance in spatial microhabitat selection. B. pfeifferi snails showed statistically significant preferences for shallow water (depth: 2–7 cm) and the preferred water velocities ranged between 12 and 21 cm s^-1 with an estimated optimum at13.3 cm s^-1. No statistically significant preferences for substratum type were found. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pathways of macroinvertebrate invasions in the Ob River basin (West Siberia)

Water bodies of West Siberia mainly belong to the Ob River basin, which is not connected to other basins by shipping canals. The relative isolation of the basin predetermined the major role of industrial fisheries and aquarium trade in alien invertebrate transfer into the basin reservoirs. About 60% of the alien species were introduced into water bodies of West Siberia through industrial fisheries, and about 40% through aquarium fisheries. This paper is the first attempt to supplement a list of alien aquatic invertebrates from the Ob River basin. The data on the spread of 21 known non-indigenous species of invertebrates in this area are available. It should be noted that 7 species were deliberately introduced to enhance food reserves for fish, 8 were released by aquarists, 5 were inadvertently released during fish and forage organism introduction, and 1 (a crayfish) was imported for human consumption. For species with a known establishment period, there was a prolonged lag time in cases of both intentional and inadvertent introduction. The high invasion rate in the relatively isolated water bodies of the Ob River basin is comparable to that in Europe; hence, establishment of control over fishery-induced movement of alien invertebrates is required.     

Spatial genetic structure of a small rodent in a heterogeneous landscape

Gene flow in natural populations may be strongly influenced by landscape features. The integration of landscape characteristics in population genetic studies may thus improve our understanding of population functioning. In this study, we investigated the population genetic structure and gene flow pattern for the common vole, Microtus arvalis, in a heterogeneous landscape characterised by strong spatial and temporal variation. The studied area is an intensive agricultural zone of approximately 500 km² crossed by a motorway. We used individual-based Bayesian methods to define the number of population units and their spatial borders without prior delimitation of such units. Unexpectedly, we determined a single genetic unit that covered the entire area studied. In particular, the motorway considered as a likely barrier to dispersal was not associated with any spatial genetic discontinuity. Using computer simulations, we demonstrated that recent anthropogenic barriers to effective dispersal are difficult to detect through analysis of genetic variation for species with large effective population sizes. We observed a slight, but significant, pattern of isolation by distance over the whole study site. Spatial autocorrelation analyses detected genetic structuring on a local scale, most probably due to the social organisation of the study species. Overall, our analysis suggests intense small-scale dispersal associated with a large effective population size. High dispersal rates may be imposed by the strong spatio-temporal heterogeneity of habitat quality, which characterises intensive agroecosystems.     

Features of moss mat structure and productivity in forest-bog complexes of West Siberia

The species composition and distribution of mosses over microrelief features on bogs have been assessed with various types of the water-mineral nutrient supply. The density of moss stalks in different moss species mats has been examined. Fraction analysis has been applied to weight and morphological characteristics of moss stalks. The contributions made by each fraction to the biomass production have been estimated. The linear and weight parameters of the photosynthesizing layer in mosses have been determined.     

Modern gas-exchange processes in forest-steppe sphagnum bogs in the Baraba (West Siberia)

Peculiarities of forming emission flows of carbon dioxide and methane in forest-steppe raised Sphagnum bogs have been studied in view of coenotic structure and damage to the vegetation as a result of fire. The reasons of relatively low rate of methane emission in pine-dwarf shrub Sphagnum bogs under the marginal conditions have been analyzed. The concentrations of CH₄ and CO₂ in bog waters have been presented.     

Lichen biota of West Siberia

The author has surveyed the diversity of lichen biota of West Siberia and distribution of lichens over its two geographic parts: the West Siberian Plain and the mountain frame in the south of West Siberia. The diversity of lichen biota in entire West Siberia is currently estimated at 1845 species in 325 genera and 95 families. The diversity of the West Siberian Plain is estimated at 1421 species in 271 genera and 86 families, and that of the southern mountains of West Siberia, at 1682 species in 312 genera and 94 families.     

Spatial structure of the caddisfly (Insecta,Trichoptera) communities in a river basin in NW Spain affected by coal mining

The changes in caddisfly community structure and composition in the Sil River basin (NW Spain), associated with a gradient in natural conditions and a succession of alterations induced by human activity (mainly urban wastes and coal mining), were studied. Twenty-nine Trichoptera taxa belonging to 11 families were collected. The community diversity analysis showed important spatial differences from source to mouth. Towns and, above all, coal mines produced an increase in sulphate and chloride concentrations and conductivity, which adversely affected the trichopteran assemblages. A stepwise regression model, which introduced sulphate and chloride as variables, explained the changes in diversity produced in the basin (r=0.837, p< 0.01). The lowest diversity and richness values were recorded in the rivers suffering the greatest impact from coal mining or urban wastes. The heterogeneity values of the communities for the main rivers were clearly different. The greatest community heterogeneity corresponded to the main axis of the basin and was explained by spatial variability in water chemical composition. No relation was detected between structural changes at spatial level and geographical distance, such that pollution processes basically controlled the dynamics of the Trichoptera communities. Partial-CCA using distance from the source as a covariable revealed alkalinity and urban and mining-derived pollution as the main factors influencing caddisfly distribution. However, an ordination of sites in relation to the corresponding vectors did not fully agree with the chemical characteristics of the water. The species composition of the Trichoptera communities, therefore, did not seem to be good indicators of the chemical features of the rivers. The structure of the community (as expressed by richness and the Shannon index) appeared to be the better indicator of pollution.     

Greenhouse gas emission in West Siberia

The major gases contributing to the greenhouse effect are carbon dioxide and methane (60 and 15–18%, respectively). The former Soviet Union area accounts for 11% of the global methane flux on the average. However, virtually no records of methane flux were kept in Russia in the late 1980s-early 1990s. Inventories of methane emission in Russia were reported in the middle 1990s, but those data were confined to measurements performed by the early 1990s. This paper presents generalized data on methane and carbon dioxide emission from the surfaces of marsh ecosystems in West Siberia in the 1990s, when the majority of measurements were carried out.