A. V. Krylov

The influence of bird colonies on the zooplankton in the Rybinsk Reservoir overgrown shallows

This article describes the peculiarities of the structural organization of zooplankton influenced by the waste products of the black-headed gull (Larus ridibundus Linnaeus) nesting colony in the protected overgrown shallow in Rybinsk Reservoir. The bird colony facilitates a modification of the zooplankton structure that is similar to the modifications of communities at early stages of eutrophication: the number of invertebrate species increases thanks to rotifers and cladocerans and the number and biomass of community increases due to cladocerans and copepods.

The species composition of zooplankton in waterbodies and watercourses of the great lakes depression

The species composition of zooplankton in lakes, reservoirs, and watercourses of the Great Lakes Depression (Mongolia) is examined. Its changes depending on the type of water objects and water mineralization are shown. Under changes in the climate and the economic situation in Mongolia, the species diversity in fresh waterbodies is seen to increase, which is also due to species that are indicators of eutrophication. The minimum changes in the species composition take place in highly mineralized lakes where zooplankton is characterized by the lowest species diversity. The formation of the zooplankton faunistic composition corresponds to changes that were observed earlier in reservoirs of the Volga cascade. The species composition of zooplankton in watercourses varies significantly and depends on the character of the source of a river and its length.

Communities of hydrobionts and the physical-chemical characteristics of the estuary area of inflow of a flat water basin

The transitive and stable sites in the zone of changeable backup waters of inflow in the Ribinsk reservoir are determined on their physical-chemical parameters. The distribution of bacterioplankton and zooplankton and the density of the fish population are described. The similarities and distinctions of hydrobionts in the river, reservoir, and the zone of their water contact are shown. The zone of changeable backup waters (CBWs) is determined as ecotone according to its number of typical features.

Specific features of the zooplankton of the coastal zone of Lake Sevan

Specific features of the Lake Sevan zooplankton development during a rise in water level in July 2007 and a change in the fish density were revealed. Compared to earlier data (from the second half of the 20th century), the pelagial zooplankton quantitatively dominates over the zooplankton of shallows. It is shown that the diversity and abundance of rotifers increase in the coastal zones subject to inundation. The rotifer indicator species of eutrophic and α-mesosaprobic waters contribute to this increase. The stimulating effect of the waste products of a bird colony on the zooplankton of the lake shallows is revealed.

Zooplankton in Lake Sevan during the period of high water level and low fish density

It is shown that, upon the flooding of ephemeral waterbodies in the coastal region and the formation of new warmer sites of the shoals due to the rising water level in Lake Sevan in 2011, species typical for temporary waterbodies and various shoals have been recorded in the zooplankton. Among them, Daphnia (Ctenodaphnia) magna Straus reached mass development, which was favored by the minimal control from “the top” and favorable trophic conditions. Owing to the abovementioned factors, the total lake zooplankton biomass and water transparency increased. The uneven distribution of D. (C.) magna was determined by the density of fish that prefer it as food.

Zooplankton of the drying lake Orog (Mongolia)

Interannual differences in zooplankton parameters of the drying lake Orog depend on the water level and the influence of the lake’s tributary. When the water level is high and pastures are especially close to the shoreline, the zooplankton structure indicates a hypertrophic status. When the water level decreases, pastures are far from the shoreline, and a large proportion of the body of water comes from the tributary, the zooplankton structure characterizes the lake as an oligotrophic waterbody; when the tributary dries up, it is characterized as mesotrophic.

Impact of the activities of beaver on the zooplankton of a piedmont river (Mongolia)

The activities of beavers, even in the absence of construction, promote the increase of abundance and the change of community composition in zooplankton. Size of populations, biomass, abundance of copepods, number of species, and value of the Shannon biodiversity indices all increase in parts of the river with some water flow. Biomass and abundance of cladocerans increase in stagnant floodplain waterbodies, along with the reduction of the number of species and of the uniformity of communities.

Zooplankton in the zones of confluence of unregulated rivers

The hydrophysical characteristics and indices of zooplankton are given for the confluence zones of small and medium tributaries and channels of the Don and Khoper rivers within the territory of Voronezh oblast. Three types of confluence areas of tributaries and recipient rivers are described. In these areas the water masses mix and habitats differing in physical parameters of water and structures of aquatic animal communities are formed.

Structure of heterotrophic plankton in the littoral zone of the plain reservoir under effect of hydrophilic birds

The eutrophic effect of products of vital activity of colonies of hydrophilic birds on the community of heterotrophic plankton in shallow parts of the plain reservoir is shown. The strongest effect of birds is observed in a protected part of the reservoir. Specific changes in some characteristics of zooplankton as distinct from the response to the anthropogenic effect are found.

Water masses and zooplankton in a tributary of the Rybinsk Reservoir in its backwater zone

In 2008, transition (gradient) and stable zones in backwaters of the tributary of the Rybinsk Reservoir were distinguished according to water conductivity. The highest values of BOD5 (biochemical oxygen demand) and the maximum zooplankton abundance within the backwater zone as well as in comparison with the neighboring systems (the river and the reservoir) were recorded in the transition zone where the marginal effect appeared.