Pup production and breeding distribution of the Caspian seal (Phoca caspica) in relation to human impacts

Aerial surveys of Caspian seals on the winter ice field in Kazakhstan territorial waters were carried out in February 2005 and 2006 to assess the annual pup production for the species and natural predation on newborn pups. Estimated pup production was 21063 in 2005 and 16905 in 2006 (including an estimated figure for pups born in Russian territory in each year). The breeding population size of approximately 20 000 females is much less than published estimates from the late 1980s. Eagles were the principal natural predators of pups. Commercial icebreaker routes passed through areas of dense pup concentrations in 2006, although not in 2005. Our findings have important implications for the development of conservation strategies for the species. Natural mortality, loss to predators, and, more important, the current hunting quota substantially exceed the recruitment of the Caspian seal population. Anthropogenic sources of mortality should be managed to avoid further declines in the species.     

Use of sibling relationship reconstruction to complement traditional monitoring in fisheries management and conservation of brown trout

Declining trends in the abundance of many fish urgently call for more efficient and informative monitoring methods that would provide necessary demographic data for the evaluation of existing conservation, restoration, and management actions. We investigated how genetic sibship reconstruction from young‐of‐the‐year brown trout (Salmo trutta L.) juveniles provides valuable, complementary demographic information that allowed us to disentangle the effects of habitat quality and number of breeders on juvenile density. We studied restored (n = 15) and control (n = 15) spawning and nursery habitats in 16 brown trout rivers and streams over 2 consecutive years to evaluate the effectiveness of habitat restoration activities. Similar juvenile densities both in restored and control spawning and nursery grounds were observed. Similarly, no differences in the effective number of breeders, N_b(SA), were detected between habitats, indicating that brown trout readily used recently restored spawning grounds. Only a weak relationship between the N_b(SA) and juvenile density was observed, suggesting that multiple factors affect juvenile abundance. In some areas, very low estimates of N_b(SA) were found at sites with high juvenile density, indicating that a small number of breeders can produce a high number of progeny in favorable conditions. In other sites, high N_b(SA) estimates were associated with low juvenile density, suggesting low habitat quality or lack of suitable spawning substrate in relation to available breeders. Based on these results, we recommend the incorporation of genetic sibship reconstruction to ongoing and future fish evaluation and monitoring programs to gain novel insights into local demographic and evolutionary processes relevant for fisheries management, habitat restoration, and conservation.     

Effects of food availability on dispersal and cub sex ratio in the Mednyi Arctic fox

Since the Pleistocene, Arctic foxes, Alopex lagopus, on Mednyi Island in the North Pacific have been isolated in a small area with rich food resources and no other terrestrial carnivores. This situation provides an unusually simple system within which the effect of food dispersion on demography and social organisation was examined. We studied the composition, location and dispersal of 67 Arctic fox groups and mapped their major food resources (seabird colonies) during 1994–2000 on Mednyi. We compared our observations with the predictions of models of sex-ratio determination. Our observations are most consistent with the predictions of Julliard's (2000) model, where mothers are expected to produce more offspring of the most dispersing sex in low-quality habitats, and more offspring of the most philopatric sex in high-quality habitats. The polygynous foxes on Mednyi Island lived where the principal food resources were patchily distributed (present on 11% of the shoreline), and cub survival to dispersal age or reproductive adult was higher in rich (25/45) than in poor (24/79) home ranges. Furthermore, dispersal was strongly sex-biased: most females (60%) remained on their natal ranges, whereas very few males (9%) did so. Significantly more female than male cubs (54 compared with 24) emerged from dens in resource rich ranges, whereas the sex ratio on poor ranges was approximately equal (51 females and 56 males). While our observations are also to some extent consistent with the local resource enhancement (LRE) hypothesis (which predicts a bias towards the sex most likely to cooperate with parents), this does not account for the observed spatial variability.     

Reproduction of mountain birch along a strong pollution gradient near Monchegorsk, Northwestern Russia

We explored effects of severe pollution on sexual reproduction of mountain birch, Betula pubescens subsp. czerepanovii, by counting catkins on sample branches and weighing both somatic and generative structures of both short and long shoots from birches growing at 21 sites around large nickel-copper smelter at Monchegorsk, Northwestern Russia. Proportion of reproducing trees, production of catkins, shoot and catkin weight, as well as the relative difference in weight of somatic structures of generative and vegetative shoots, were generally independent of pollution load; in 2003 birches growing in industrial barrens produced more catkins than birches growing in unpolluted forests. Thus, we found no support for the hypothesis that reproductive allocation should decrease with decrease in environmental capacity. Absence of adverse effects might indicate that long-lasting pollution impact already eliminated the most sensitive individuals from the affected birch populations.     

Copper-binding efficacy of water-soluble chitosans: characterization by aqueous binding isotherms

The major objective of the study is to measure directly the isotherms of copper binding onto soluble chitosan preparations, using ion-selective electrode technique. Copper uptake is found to decrease strongly when chitosan acetylation degree or chitosan concentration increased. When relating the bound copper concentrations to content of non-acetylated amine groups in a chitosan, differences between copper uptake on different chitosan preparations become reduced but not disappear. Other effects, in addition to the contents of non-acetylated amine groups, can involve differences in the copper binding by different chitosans. Due to isotherm non-linearity, the distribution coefficient K(d) of copper between a water-soluble chitosan and an aqueous solution may vary by two orders of magnitude as the free copper concentration C(free) varied. Linear relation between logK(d) normalized by free amine group content of chitosans and logC(free) may help in preliminary estimating of the copper binding by water-soluble chitosans at a certain pH.     

Analysis of Factors Determining Accumulation of 137Cs by Woody Plants

The accumulation of ¹³⁷Cs by coniferous (Pinus sylvestris) and deciduous (Betula pendula) trees was studied in the area contaminated with radioactive products after the Chernobyl accident. The availability of ¹³⁷Cs to woody plants is determined by its vertical distribution in the soil profile, the proportion of its exchangeable form, and the distribution of tree roots in the soil. The index of biological availability of ¹³⁷C in the soil is proposed, and its linear dependence on the coefficients of ¹³⁷Cs transfer to wood is demonstrated.     

Competition and facilitation in industrial barrens: variation in performance of mountain birch seedlings with distance from nurse plants

In stressful environments inter-plant facilitation is an important phenomenon co-occurring with competition. However, most experiments in natural ecosystems have only contrasted "sheltered" and "exposed" microsites, thus missing possible non-linearity of effects and not giving any information about the scale at which these interactions operate. In the current experiment we studied the net effect of nurse trees on mountain birch seedlings at various planting distances. Seedlings were planted in two highly stressful subarctic industrial barren sites around the nickel-copper smelter in Monchegorsk, NW Russia, at five distances (from 10 to 100 cm) from mature birch trees that were circa 100 cm in height. The survival and growth of seedlings were monitored for six years and the results were analyzed in respect to several environmental characteristics. Despite the fact that interaction strengths varied between years and between two study sites, both survival and growth of seedlings indicated optimum performance at middle distances and decreasing performance closer to and further from the nurse tree. We suggest that adverse effects on seedling performance at short distances are explained by competition and/or accumulation of pollutants under nurse plants, whereas at long distances these adverse effects appear due to lack of shelter, as shown by higher wind stress and lower soil water content.     

Root fungal colonisation in Deschampsia flexuosa: effects of pollution and neighbouring trees

In industrial barrens adjacent to a nickel-copper smelter at Monchegorsk, the Kola Peninsula, root colonisation in Deschampsia flexuosa by arbuscular mycorrhizal (AM)-type of hyphae was lower than in unpolluted forests (60.9 vs. 80.4%), while Olpidium-colonisation showed a marginally significant decline, and dark septate endophytic (DSE) hyphal colonisation was not affected. We detected an interactive effect of pollution and a neighbouring tree on DSE hyphal colonisation: at the highly polluted sites, colonisation was lower in D. flexuosa growing near trees, whereas at sites with low pollution the presence of the neighbouring tree had no effect on colonisation. High numbers of intracellular DSE sclerotia in the industrial barrens (13.3 vs. 3.4%) may indicate a survial strategy in an unfavourable environment and a dispersal strategy into a more favourable environment. While lower root colonisation by AM fungi has been also earlier reported in graminoids for heavy metal contamination, the results on other ubiquitous fungi colonising D. flexuosa roots are more novel.     

Budburst phenology of white birch in industrially polluted areas

Effects of environmental contamination on plant seasonal development have only rarely been properly documented. Monitoring of leaf growth in mountain birch, Betula pubescens subsp. czerepanovii, around a nickel-copper smelter at Monchegorsk hinted advanced budburst phenology in most polluted sites. However, under laboratory conditions budburst of birch twigs cut in late winter from trees naturally growing around three point polluters (nickel-copper smelter at Monchegorsk, aluminium factory at Kandalaksha, and iron pellet plant at Kostomuksha) showed no relationship with distance from the emission source. In a greenhouse experiment, budburst phenology of mountain birch seedlings grown in unpolluted soil did not depend on seedling origin (from heavily polluted vs. clean sites), whereas seedlings in metal-contaminated soil demonstrated delayed budburst. These results allow to attribute advanced budburst phenology of white birch in severely polluted sites to modified microclimate, rather than to pollution impact on plant physiology or genetics.     

The Selenga River delta: a geochemical barrier protecting Lake Baikal waters

Regional Environmental Change - The protection of Lake Baikal and the planning of water management measures in the Selenga River Basin require a comprehensive understanding of the current state and...