Volume 43, Nº 10 (2016)

This review summarizes published data on the genetic markers used in studies of dreissenide invasions. Causes of genetic differences between local populations are discussed. It is shown that information about the genetic diversity of populations obtained by marker polymorphism analysis should be compared to study invasion directions.

The abundance dynamics of adult dreissenids (Dreissena polymorpha (Pallas) and D. bugensis Andrusov) and of their larvae and the spatial distribution of the abundance of veligers and their role in the functioning of the plankton community have been analyzed on the basis of the data of original long-term monitoring (2004–2013) in Rybinsk Reservoir. The dreissenid veligers are most abundant in the summer time (July to August) when their number is comparable to that of the filter-feeding crustaceans and their biomass is close to that of rotifers. Before 2010 the production of veligers during the vegetation season comprised about 5% of the production of metazooplankton and the food consumption was about 1% of the primary production of phytoplankton. Pelagic invertebrate predators consumed about 90% of the production of veligers for the vegetation period. After 2010, the abundance of dreissenid larvae and their functional characteristics decreased by a factor of 5–6. Trophic relationships between zooplankton and veligers are discussed.

This article presents results of long-term studies of the communities of Zebra mussel and Quagga mussel in the cooling pond of the Chernobyl Nuclear Power Plant (Ukraine). The peculiarities of the sequential invasion of these two species and the formation of consortium-type communities by them are considered.

Data on the occurrence of Gibel carp in flowing water bodies of the Don River basin and the Lower Volga River basin are given. It is shown that gibel carp actively seeks for habitats with flowing water and can persist for a long time in streams with a current velocity from 1.0 to 1.3 m/s and overcome chutes with a current velocity of 2.6 m/s and streams with a depth of less than the body depth of the fish. Therefore, gibel carp is proposed to be considered as a lake–river fish. The outbreak of this species in streams is associated with its spawning period, when it moves in search of spawning grounds. It is assumed that these movements may contribute to its settling in rivers.

The structural and functional properties of the bacterioplankton in two small rivers and the Sheksna River that run through the large industrial city of Cherepovets were studied from April to October 2009–2011. The three-year average numbers and biomass of planktonic bacteria in small rivers were 18.7–18.8 million cells/mL and 3.5–4.9 g/m³, respectively; these values in the Sheksna River’s littoral zone were 15.8 million cells/mL and 2.2 g/m³. The bacterioplankton production in the small water courses exceeded that in the Sheksna River by a factor of 1.8–2.2. The contribution of bacterial filaments to the total biomass and the total bacterioplankton production increases in small polluted rivers.

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.

According to our data on the density of breeding pairs of five lark species obtained from route censuses, the dynamics of their population in the Mezhuzenskii and Uzensko-Dyurinskii landscapes of the semidesert in the Caspian lowland is considered. Our five-year census work was carried out on key sites 25 km² in area, with mapping and description of the soils and vegetation using remote sensing techniques. Our comprehensive studies of these key areas have revealed the dynamics of the individual lark species characteristic of the northwestern part of the Trans-Volga region of the Caspian lowland and the changes in the level of vegetation of the plant component of individual landscape tracts depending on the moisture level in certain years. It is shown that, in the monotonous plain conditions, an important role in the distribution of the specific population of larks is played by the meso- and micro-relief, which determines the soil salinity, and the distribution of moisture and vegetation groups (which predetermine the features of bird habitats). The interannual variability of the population structure of larks is shown, which, in the modern conditions of consistently low anthropogenic pressure, is determined by the weather in specific years, which determines the level of vegetation and, therefore, changes in the nesting conditions of birds in specific habitats.

A wavy trend toward increasing vegetation biomass in desert, semidesert, and steppe communities growing on solonetzic soils was discovered in the Northern Caspian region over a 60-year observation period (1952–2013). The trend is caused by warming during winter months (due to redistribution of soil moisture) and the improvement of hydrothermal conditions in spring months (the period of most active plant vegetation).

As a result of our long-term research (1978–2013), the spatial structure patterns of American mink (Neovison vison Schreber, 1777) populations, their nutrition, and daily and seasonal activity in the floodplain and right-bank ecosystems of the Volgograd water reservoir have been revealed. The average size of the home ranges of the mink is 22.4 ha for females and 34.7 ha for males on the islands. On the right shore of the reservoir, they are significantly larger, namely, 51.3 and 75.5 ha, respectively. The diet of the mink is based on three forage groups: mammals (primarily mouselike rodents) (18.8–42.7% BIO), fish (5.6–39.1% BIO), and amphibians (17.1–51.7% BIO). Other food is significant only in certain seasons. On the floodplain islands, the mink is the most active in spring and fall, while its summer activity decreases, and in winter the daily rhythm clearly has two peaks, the morning and evening ones. On the right bank, due to the food scarcity in some seasons, the activity peaks are smooth.

The species composition of Chironomus in the Curonian Lagoon has been investigated. It was shown that three sibling species of the plumosus group, namely, Ch. plumosus, Ch. balatonicus, and Ch. muratensis, and a first-generation interspecific hybrid Ch. muratensis × Ch. plumosus lived here. The occurrence frequency in the lagoon was 87, 19, 6, and 3% for Ch. plumosus, Ch. balatonicus, Ch. muratensis × Ch. plumosus, and Ch. muratensis, respectively. The species Ch. plumosus was recorded in all the areas (southern, central, and northern), while Ch. balatonicus was found only in the northern area in the village of Juodkrante near the city of Klaipeda. Presumably, the distribution of these sibling species is due to the presence of a salinity gradient in the lagoon.

A phytolithic study was made on the territory of the archaeological site Tytkesken’-2 to reconstruct the stages of plant cover transformation. Phytoliths of grasses growing on the research site and the phytolithic composition of the soil profile containing the cultural horizons of the Neolithic, Eneolithic, Bronze, and Scythian ages were studied. The comparison of the modern plant phytoliths with the silica soil particles revealed information about the anthropogenic and climatic changes of plant cover on the site. Our important achievement is identification of the stage of maximum anthropogenic impact on the plant cover of the area during the Final Neolithic.

Data on the distribution, ecology, and biology of the ant Camponotus fedtschenkoi Mayr, 1877 (Hymenoptera, Formicidae) in Bogdinsko–Baskunchakskii State Nature Reserve (the only known habitat of this species in Russia) have been given. Critical analysis of the published data on the ecology and biology of the species has been provided.