Copper and zinc in four freshwater fish species from Lake Pamvotis (Greece)

Lake ecosystems are vulnerable to heavy-metal pollution. Fish samples are considered as one of the most indicative factors, in freshwater systems, for the estimation of trace metals pollution potential. Lake Pamvotis (NW Greece) is a typical Mediterranean ecosystem of great importance in regard to biodiversity and to aesthetic value. The fish species found most commonly in the lake are Cyprinus carpio, Silurus aristotelis, Rutilus ylikiensis, and Carassius gibelio. The aim of the present study is to evaluate the level of contamination of two essential heavy metals (copper and zinc) appearing at high concentrations in lake water in the above four fish species. Metal concentrations were measured by atomic absorption spectroscopy in three different tissues (muscle, liver, gonads) in order to assess the fish contamination. A two-factor analysis of variance, based on the procedure of general linear models, was employed in which fish species (four levels) and fish tissue (three levels) were examined for potential influence on Cu and Zn concentrations. Differences between level means per factor were treated using Tukey's multiple comparisons of means. The study showed that C. carpio and R. ylikiensis presented the highest metal content. Tissues analysis revealed that liver and gonads accumulated the highest levels of Cu and Zn. Metal concentration in the edible part of the examined fish (muscle) were in the safety-permissible levels for human consumption.     

Heavy metals in four fish species from the French coast of the Eastern English Channel and Southern Bight of the North Sea

Shallow coastal waters act as nurseries for various fish species and have been recognized as essential fish habitat. We studied heavy metal concentrations in four fish species (plaice, dab, flounder and cod) as an indicator of large-scale habitat quality. The study took place along the French coasts between the Eastern English Channel and the Southern Bight of the North Sea. All species show different concentrations of measured metals (e.g., Cd, Cu, Mn and Pb) in liver but not in muscle. The highest concentrations are found for the flounder and the lowest for cod which is consistent with their habitat and diet. Although our results do not highlight levels of appreciable pollution within the study area, inter-site differences are mainly observed in the muscle tissues and are generally in agreement with the known environmental data (e.g., anthropogenic pressure). However, in the Bay of Seine, one of the most contaminated estuaries in Europe, metal concentrations are in the same range or even lower than those found in fish collected from areas distant from any anthropogenic pressures. At one site, the comparisons of the Cd, Cu and Pb concentrations between healthy and diseased dabs have been carried out on the muscle and liver tissues. The results of this preliminary study show a relationship between metal concentrations and the pathological status of the fish. The use of fish health as indicator of habitat quality is discussed.     

137Cs contamination in tea and yerba mate in South America

Gamma-ray spectra from more than 50 samples of food products available in stores of Buenos Aires city were measured using a germanium detector. Activity concentrations of 137Cs up to 10 Bq/kg were found in tea and yerba mate manufactured in Apóstoles, Argentina. Further measurements of tea leaves, yerba mate leaves and soils, all coming from a cultivated area in that region, also show the presence of 137Cs contamination. The results suggest that the area was fertilized with a product that originated in a region affected by the fallout from the Chernobyl nuclear plant accident.     

The Spatiotemporal Structure of Rodent Populations in the Steppe Zone of Western Siberia

The spatial structure of populations has been studied in two rodent species inhabiting the subzone of meadow steppes of the steppe zone of Omsk oblast: the narrow-sculled vole (Microtus gregalis Pall.) and steppe lemming (Lagurus lagurus Pall.). Their populations are represented by combinations of territorial family groups whose structure and spatial distribution vary by season depending on population density, the phase of the population cycle, and the status of their members in the population. In the areas cohabited by M. gregalis and L. lagurus, the pattern of territory use and the rhythm of animal activity during the day depend primarily on their total density: under conditions of low density, the population groups of both species are spatially separated; at increased density, they are distributed with respect to the pattern of daily activity. Both species jointly use part of the territory but at different times of day: M. gregalis, mainly at night and in the morning; L. lagurus, in the daytime.     

Effect of Climatic Factors on the Growth of Representatives of the Genus Pinus (Pinaceae) under Conditions of Introduction

Four introduced and one aboriginal species of the genus Pinus L. have been studied in the middle taiga subzone of southern Karelia. Significant interspecific differences in the dates of onset, cessation, and peak of the growth of shoots and needles have been revealed. It has been shown that their annual increment depends on the rate of growth, rather than on its duration. The dynamics of shoot and needle growth in introduced and aboriginal species, though largely similar, differ in some respects. These differences reflect species-specific responses to hydrothermal conditions in a certain growing season.     

Geographic Variation in the Seasonal Reproductive Strategy of the Mite Varroa jacobsoni in the Honeybee Nest

Variation in the reproduction of Varroa jacobsoni mite was studied in relation to the expansion of the range of its parasitism on the honeybee. Geographic differences in the seasonal dynamics of mite reproduction in the nests of bee families were revealed. Variation in the sex ratio of mites and the factors inhibiting their reproduction at the northern boundary of the honeybee range are considered. The forms of parthenogenetic reproduction in V. jacobsoni are discussed.     

Long-Term Changes in the Fauna of Diurnal Lepidopterans (Lepidoptera,Diurna) in the Northern Taiga Subzone of the Western Russian Plain

In the diurnal lepidopteran fauna of the northern taiga subzone in the western Russian Plain, the species inhabiting primary biotopic complexes typical of this subzone currently account for slightly more than 60% of the total species richness and abundance. A large part of the fauna is represented by the species of more southern origin, whose expansion to the northern taiga was caused by anthropogenic transformation of landscapes between the 12th and 20th centuries and recent climate warming.     

Effect of water pH and total dissolved solids on the species diversity of pelagic zooplankton in lakes: A statistical analysis

Statistical analysis of the combined influence of lake surface area (S), water pH, and total dissolved solids (TDS) on the formation of zooplankton communities in lakes has been made on the basis of available data on the number of species (N _sp ) of pelagic zooplankton in 256 lakes of the temperate zone of Europe, Asia, and North America. Graphic analysis and analysis of variance have shown that extremely high or extremely low values of pH and TDS inhibit lake zooplankton. If the value of one of these factors is extremely high, any increase in the other factor is favorable for the inhibited zooplankton, and this second factor determines the value of N _sp .     

Anthropogenic Transformation of Flora in the City of Astrakhan and Its Environs over the Past 100 Years

Trends in the anthropogenic transformation of flora in the city of Astrakhan and its environs over the past 100 years are discussed. In general, the process of flora synanthropization is observed, with natural aboriginal plant communities being replaced by anthropogenically altered communities.