Frequency of Iris Depigmentation in Urban Populations of Rana arvalis Frogs

Russian Journal of Ecology -     

Topography of morphological abnormalities and mate selection in the toads Bufo bufo L., 1758 and B. viridis Laur., 1768

Collection material (the Museum of the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences) on the common and green toads collected by L.Ya. Toporkova in 1976–1977 in the Middle and Southern Urals was analyzed. In addition to species-specific characteristics of mate selection, differences in the frequency and the pattern of topographic confinement were found. They were determined by different mating models and differences in the degree of ecological flexibility of the species studied.     

Proliferative Activity of Corneal Epithelium and Specific Features of Morphogenesis in Postmetamorphic Rana arvalisNilss. in Urbanized Areas

The mitotic activity and sizes of corneal epithelial cells in postmetamorphic Rana arvaliswere studied in the populations exposed to different degrees of anthropogenic impact in the city of Yekaterinburg. The studies were conducted at the initial stages of frogs' terrestrial life in three consecutive years. Mitotic activity exhibited a slight positive correlation with the liver index, which indirectly reflects the general metabolic rate in young frogs. The combined estimation of proliferative activity, epithelial cell size, and relative liver weight had the highest information value. There was a relationship between the mitotic index and liver index in young frogs from habitats with the highest level of anthropogenic transformation. This indicates that morphogenesis is well-balanced and is likely to decrease the probability of morphological abnormalities in frogs developing in the unstable environment. This physiological property allows the populations to exist and reproduce in urbanized areas.     

Comparative analysis of the parasitocenoses of amphibians from the family Ranidae (Anura) in the urbanization gradient

The parasitofauna of frogs from the fam. Ranidae (R. arvalis, R. temporaria, and P. ridibundus) has been studied in the urbanization gradient. A total of 22 parasitic species belonging to the following four taxonomic groups have been found: Protozoa, Trematoda, Monogenoidea, and Nematoda. The transformation of parasitocenoses with the growth of urbanization along with the preservation of specifics typical for the adaptive subzone in each amphibian species is accompanied with their depletion as well as with an increase in the proportion of trematodes, which results in a decrease in the system stability and increases the probability of parasitic pollution of the environment.     

Specific Features of the Formation of Animal Species Communities in Technogenic and Urbanized Landscapes

The formation of the species composition and specific functional, physiological, and phenotypic features of populations in technogenic and urbanized areas was studied by analyzing murine rodents, amphibians, and soil invertebrates. It is shown that, against the background of decreasing total abundance and biomass of animals, their formerly continuous ranges become mosaic, with the locally increasing animal density and heterogeneity and specific population dynamics. Species diversity decreases; however, species alien to the natural ecosystems of the given territory appear. Changes in the strategies of reproduction and food resource use were revealed in the species communities of small mammals and amphibians.     

Trophic specificity of theRana arvalis population from the eastern ural radioactive trace in relation to the state of the soil mesofauna

Studies on the population ofRana arvalis Nilss. frogs performed in the radioactively contaminated area near Lake Berdanish in 1993 revealed a number of features indicating that the contents of nutrients in the organisms of adults and juveniles is low. The analysis of simultaneously collected data on food supply to this population showed that the structure of food chains in the study area is simplified and the diversity and biomass of soil invertebrates (the main food for amphibians) are sharply reduced. These factors account for food deficiency, which manifests itself in a low level of stomach filling and individual energy reserves of the frogs and is reflected in their population characteristics.     

Revealing the factors affecting occurrence and distribution of polycyclic aromatic hydrocarbons in water and sediments of Lake Baikal and its tributaries

The concentrations of polycyclic aromatic hydrocarbons (PAH), total carbon (TC), total organic carbon (TOC), total nitrogen (TN) and dissolved inorganic nitrogen (DIN) in water and sediments of Lake Baikal and its tributaries were measured. It was found that according to existing water and sediment quality standards limiting permissible PAH concentrations, both surface waters and sediments in Lake Baikal watershed can be considered as unpolluted with PAHs compounds. Nevertheless, the spatial distribution of PAH concentrations in lake water indicates the existence of some point PAH sources in and around the lake. These sources were natural oil seeps and communal facilities such as residential coal-fired and oil-fired boilers. It was observed that concentrations of PAHs in both water and sediments are controlled by organic matter content and organic matter mineralisation degree, as indicated by PAH-to-carbon and nitrogen-to-carbon ratios respectively. It was found that PAH/TOC and PAH/TC ratios characterise PAH loading on water and sediments respectively, whereas DIN/TOC and TN/TC ratios characterise self-purification of water and sediments respectively. It was proved that PAH/TOC and DIN/TOC ratios can be used as tracers to evaluate the PAH contributions from tributaries to Lake Baikal.